Elgg master Documentation¶

Elgg (pronunciation) is a rapid development framework with built-in social features. It is a great fit for building any app where users log in and share information.

It has been used to build all kinds of social apps:

open networks (similar to Facebook)

topical (like the Elgg Community)

private intranets

dating

educational

company blog

This is the canonical documentation for the Elgg project.

Getting Started¶

Discover if Elgg is right for your community.

Features¶

Showcases: https://elgg.org/showcase

For developers¶

Permissive license

Theme framework

Internationalization

Templating engine

Widgets framework

Plugin APIs

Social graph

Web services API

jQuery-based JS framework

Session management

Custom URL routing

For admins¶

User profiles and avatars

Fine-grained access control lists

Friends and friends lists (ala G+ circles)

Responsive, mobile-friendly design

RSS support

Activity stream

Plugins for common content types like blogs, bookmarks, files, microblogging, private messages, documents, message boards, discussion

User authentication and administration

If you need more functionality than what Elgg offers out-of-the-box there are a couple of options:

Add more by installing plugins - for example, blogs, forums, social bookmarks

Develop your own features via plugins

Hire someone to do the above for you

Bundled plugins¶

Elgg comes with a set of plugins. These provide the basic functionality for your social network.

Blog¶

A weblog, or blog, is arguably one of the fundamental DNA pieces of most types of social networking site. The simplest form of personal publishing, it allows for text-based notes to be published in reverse-chronological order. Commenting is also an important part of blogging, turning an individual act of publishing into a conversation.

Elgg’s blog expands this model by providing per-entry access controls and cross-blog tagging. You can control exactly who can see each individual entry, as well as find other entries that people have written on similar topics. You can also see entries written by your friends (that you have access to).

See also

Blogging on Wikipedia

Dashboard¶

A typical Elgg dashboard

The dashboard is bundled with both the full and core-only Elgg packages. This is a users portal to activity that is important to them both from within the site and from external sources. Using Elgg’s powerful widget API, it is possible to build widgets that pull out relevant content from within an Elgg powered site as well as grab information from third party sources such as Twitter or Flickr (providing those widgets exist). A users dashboard is not the same as their profile, whereas the profile is for consumption by others, the dashboard is a space for users to use for their own needs.

Diagnostics¶

For the technically savvy user, system diagnostics enables you to quickly evaluate the server environment, Elgg code, and plugins of an Elgg install. Diagnostics is a core system plugin that comes turned on by default with Elgg. To download the diagnostics file, follow the steps below. The file is a dump of all sorts of useful information.

To use:

Log in as Administrator
Go to Administration -> Administer -> Utilities ->System Diagnostics
Click ‘Download’

System diagnostics dump file contents:

List of all Elgg files along with a hash for each file
List of all the plugins
PHP superglobals
PHP settings
Apache settings
Elgg CONFIG values
- language strings
- site settings
- database settings
- plugin hooks
- actions
- views
- page handlers
- much more

File repository¶

A file in an Elgg file repository

The file repository allows users to upload any kind of file. As with everything in an Elgg system, you can filter uploaded files by tag and restrict access so that they’re only visible by the people you want them to be. Each file may also have comments attached to it.

There are a number of different uses for this functionality

Photo gallery¶

When a user uploads photographs or other pictures, they are automatically collated into an Elgg photo gallery that can be browsed through. Users can also see pictures that their friends have uploaded, or see pictures attached to a group. Clicking into an individual file shows a larger version of the photo.

Podcasting¶

An Elgg file repository RSS feed automatically doubles as an RSS feed, so you can subscribe to new audio content using programs like iTunes.

Special content¶

It is possible for other plugins to add to the players available for different content types. It’s possible for a plugin author to embed a viewer for Word documents, for example.

Note for developers¶

To add a special content type player, create a plugin with views of the form file/specialcontent/mime/type. For example, to create a special viewer for Word documents, you would create a view called file/specialcontent/application/msword, because application/msword is the MIME-type for Word documents. Within this view, the ElggEntity version of the file will be referenced as $vars['entity']. Therefore, the URL of the downloadable file is:

<?php echo $vars['url']; ?>action/file/download?file_guid=<?php echo $vars['entity']->getGUID(); ?>

Using this, it should be possible to develop most types of embeddable viewers.

Groups¶

A typical group profile

Once you have found others with similar interests - or perhaps you are part of a research groups or a course/class - you may want to have a more structured setting to share content and discuss ideas. This is where Elgg’s powerful group building can be used. You can create and moderate as many groups as you like

You can keep all group activity private to the group or you can use the ‘make public’ option to disseminate work to the wider public.
Each group produces granular RSS feeds, so it is easy to follow group developments
Each group has its own URL and profile
Each group comes with a File repository, forum, pages and messageboard

Messageboard¶

A sample messageboard placed on the profile

The messageboard - similar to ‘The Wall’ in Facebook or a comment wall in other networks is a plugin that lets users put a messageboard widget on their profile. Other users can then post messages that will appear on the messageboard. You can then reply directly to any message and view the history between yourself and the person posting the message.

Messages¶

Message notification

Private messaging can be sent to users by clicking on their avatar or profile link, providing you have permission. Then, using the built in WYSIWYG editor, it is possible to format the message. Each user has their own inbox and sentbox. It is possible to be notified via email of new messages.

When users first login, they will be notified about any new message by the messages notification mechanism in their top toolbar.

Pages¶

An Elgg Page

The pages plugin allows you to save and store hierarchically-organized pages of text, and restrict both reading and writing privileges to them. This means that you can collaboratively create a set of documents with a loose collection of people, participate in a writing process with a formal group, or simply use the functionality to write a document that only you can see, and only choose to share it once it’s done. The easy navigation menu allows you to see the whole document structure from any page. You can create as many of these structures as you like; each individual page has its own access controls, so you can reveal portions of the structure while keeping others hidden. In keeping with all other elements in Elgg, you can add comments on a page, or search for pages by tag.

Usage¶

Pages really come into their own in two areas, firstly as a way for users to build up things such as a resume, reflective documentation and so on. The second thing is in the area of collaboration, especially when in the context of groups. With the powerful access controls on both read and write, this plugin is ideal for collaborative document creation.

Note

Developers should note that there are actually 2 types of pages:

Top-level pages (with subtype page_top)
Normal pages (with subtype page)

Profile¶

An Elgg profile

The profile plugin is bundled with both the full and core-only Elgg packages. The intention is that it can be disabled and replaced with another profile plugin if you wish. It provides a number of pieces of functionality which many consider fundamental to the concept of a social networking site, and is unique within the plugins because the profile icon it defines is referenced as standard from all over the system.

User details¶

This provides information about a user, which is configurable from within the plugin’s start.php file. You can change the available profile fields form the admin panel. Each profile field has its own access restriction, so users can choose exactly who can see each individual element. Some of the fields contain tags (for example skills) limiting access to a field will also limit who can find you by that tag.

User avatar¶

The Elgg context menu

The user avatar represents a user (or a group) throughout the site. By default, this includes a context-sensitive menu that allows you to perform actions on the user it belongs to wherever you see their avatar. For example, you can add them as a friend, send an internal message, and more. Each plugin can add to this context menu, so its full contents will vary depending on the functionality active in the current Elgg site.

Notes for developers¶

Using a different profile icon

To replace the profile icon, or provide more content, extend the icon/user/default view.

Adding to the context menu

The context menu can be expanded by registering a plugin hook for ‘register’ ‘menu:user_hover’, the following sections have special meaning:

default for non-active links (eg to read a blog)
admin for links accessible by administrators only

In each case, the user in question will be passed as $params['entity'].

The Wire¶

Elgg wire plugin “The Wire” is Twitter-style microblogging plugin that allows users to post notes to the wire.

The following plugins are also bundled with Elgg, but are not (yet) documented

aalborg_theme
bookmarks
ckeditor
custom_index
developers
embed
externalpages
garbagecollector
htmlawed
invitefriends
legacy_urls
likes
logbrowser
logrotate
members
notifications
reportedcontent
search
site_notifications
tagcloud
twitter_api
uservalidationbyemail
web_services

License¶

MIT or GPLv2¶

A full Elgg package that includes the framework and a core set of plugins is available under version 2 of the GNU General Public License (GPLv2). We also make the framework (without the plugins) available under the MIT license.

FAQ¶

The following answers are provided as a convenience to you; they are not legal counsel. Consult with a lawyer to be sure about the answers to these questions. The Elgg Foundation cannot be held responsible for decisions you make based on what you read on this page.

For questions not answered here, please refer to the official FAQ for the GPLv2.

How much does Elgg cost?¶

Elgg is free to download, install, and use. If you’d like to donate, we do appreciate our financial supporters!

Can I remove the Elgg branding/links?¶

Yes.

Can I modify the source code?¶

Yes, but in general we recommend you make your modifications as plugins so that when a new version of Elgg is released, the upgrade process is as painless as possible.

Can I charge my users membership fees?¶

Yes.

If I modify Elgg, do I have to make the changes available?¶

No, if you are using Elgg to provide a service, you do not have to make the source available. If you distribute a modified version of Elgg, then you must include the source code for the changes.

If I use Elgg to host a network, does The Elgg Foundation have any rights over my network?¶

No.

What’s the difference between the MIT and GPL versions?¶

Plugins are not included with the MIT version.

You can distribute a commercial product based on Elgg using the MIT version without making your modifications available.

With the GPL licensed version, you have to include make your modifications of the framework public if you redistribute the framework.

Why are plugins missing from the MIT version?¶

The plugins were developed under the GPL license, so they cannot be released under an MIT license. Also, some plugins include external dependencies that are not compatible with the MIT license.

May I distribute a plugin for Elgg under a commercial license?¶

We believe you can, since plugins typically depend only the core framework and the framework is available under the MIT license. That said, we really recommend you consult with a lawyer on this particular issue to be absolutely sure.

Note that plugins released via the community site repository must be licensed under a GPLv2-compatible license. They do not necessarily have to be GPLv2, just compatible (like MIT).

Can we build our own tool that uses Elgg and sell that tool to our clients?¶

Yes, but then your clients will be free to redistribute that tool under the terms of the GPLv2.

Installation¶

Get your own instance of Elgg running in no time.

Contents

Requirements
Overview
Other Configurations
Troubleshooting

Requirements ¶

MySQL 5+
PHP 5.6+ with the following extensions:
- GD (for graphics processing)
- Multibyte String support (for i18n)
- Proper configuration and ability to send email through an MTA
Web server with support for URL rewriting

Official support is provided for the following configurations:

Apache server
- Apache with the rewrite module enabled
- PHP running as an Apache module
Nginx server
- Nginx with PHP-FPM using FastCGI

By “official support”, we mean that:

Most development and testing is performed with these configurations
Much of the installation documentation is written assuming Apache or Nginx is used
Priority on bug reports is given to Apache and Nginx users if the bug is web server specific (but those are rare).

Browser support policy¶

Feature branches support the latest 2 versions of all major browsers as were available at the time of the first stable release on that branch.

Bugfix release will not alter browser support, even if a new version of the browser has since been released.

Major browsers here means all of the following, plus their mobile counterparts:

Android Browser

Chrome

Firefox

IE

Safari

“Support” may mean that we take advantage of newer, unimplemented technologies but provide a JavaScript polyfill for the browsers that need it.

You may find that Elgg happens to work on unsupported browsers, but compatibility may break at any time, even during a bugfix release.

Overview ¶

Upload Elgg¶

With Composer (recommended if comfortable with CLI):

cd /path/to/wwwroot/
composer self-update
composer global require "fxp/composer-asset-plugin:~1.3"
composer create-project elgg/starter-project:dev-master .
composer install
composer install # 2nd call is currently required

From pre-packaged zip (recommended if not comfortable with CLI):

Download the latest version of Elgg
Upload the ZIP file with an FTP client to your server
Unzip the files in your domain’s document root.

Create a data folder¶

Elgg needs a special folder to store uploaded files including profile icons and photos. You will need to create this directory.

Warning

For security reasons, this folder MUST be stored outside of your document root. If you created it under /www/ or /public_html/, you’re doing it wrong.

Once this folder has been created, you’ll need to make sure the web server Elgg is running on has permission to write to and create directories in it. This shouldn’t be a problem on Windows-based servers, but if your server runs Linux, Mac OS X or a UNIX variant, you’ll need to set the permissions on the directory.

If you are using a graphical FTP client to upload files, you can usually set permissions by right clicking on the folder and selecting ‘properties’ or ‘Get Info’.

Note

Directories must be executable to be read and written to. The suggested permissions depend upon the exact server and user configuration. If the data directory is owned by the web server user, the recommended permissions are 770.

Setting your data directory to 777 will work, but it is insecure and is not recommended. If you are unsure how to correctly set permissions, contact your host for more information.

Create a MySQL database¶

Using your database administration tool of choice (if you’re unsure about this, ask your system administrator), create a new MySQL database for Elgg. You can create a MySQL database with any of the following tools:

Make sure you add a user to the database with all privileges and record the database name, username and password. You will need this information when installing Elgg.

Set up Cron¶

Elgg uses timed requests to your site to perform background tasks like sending notifications or performing database cleanup jobs. You need to configure the cron to be able to use those kind of features.

Visit your Elgg site¶

Once you’ve performed these steps, visit your Elgg site in your web browser. Elgg will take you through the rest of the installation process from there. The first account that you create at the end of the installation process will be an administrator account.

A note on settings.php and .htaccess¶

The Elgg installer will try to create two files for you:

elgg-config/settings.php, which contains local environment configuration for your installation
.htaccess, which allows Elgg to generate dynamic URLs

If these files can’t be automatically generated, for example because the web server doesn’t have write permissions in the directories, Elgg will tell you how to create them. You could also temporarily change the permissions on the root directory and the engine directory. Set the permissions on those two directories so that the web server can write those two files, complete the install process, and them change the permissions back to their original settings. If, for some reason, this won’t work, you will need to:

In elgg-config/, copy settings.example.php to settings.php, open it up in a text editor and fill in your database details
On Apache server, copy install/config/htaccess.dist to .htaccess
On Nginx server copy install/config/nginx.dist to /etc/nginx/sites-enabled and adjust it’s contents

Other Configurations ¶

Cloud9

Homestead

EasyPHP

IIS

MAMP

MariaDB

Nginx

Ubuntu

Virtual hosts

XAMPP

Troubleshooting ¶

Help! I’m having trouble installing Elgg¶

First:

Recheck that your server meets the technical requirements for Elgg.
Follow the environment-specific instructions if need be
Have you verified that mod_rewrite is being loaded?
Is the mysql apache being loaded?

Keep notes on steps that you take to fix the install. Sometimes changing some setting or file to try to fix a problem may cause some other problem later on. If you need to start over, just delete all the files, drop your database, and begin again.

I can’t save my settings on installation (I get a 404 error when saving settings)¶

Elgg relies on the mod_rewrite Apache extension in order to simulate certain URLs. For example, whenever you perform an action in Elgg, or when you visit a user’s profile, the URL is translated by the server into something Elgg understands internally. This is done using rules defined in an .htaccess file, which is Apache’s standard way of defining extra configuration for a site.

This error suggests that the mod_rewrite rules aren’t being picked up correctly. This may be for several reasons. If you’re not comfortable implementing the solutions provided below, we strongly recommend that you contact your system administrator or technical support and forward this page to them.

The .htaccess, if not generated automatically (that happens when you have problem with mod_rewrite), you can create it by renaming install/config/htaccess.dist file you find with elgg package to .htaccess. Also if you find a .htaccess file inside the installation path, but you are still getting 404 error, make sure the contents of .htaccess are same as that of install/config/htaccess.dist.

``mod_rewrite`` isn’t installed.

Check your httpd.conf to make sure that this module is being loaded by Apache. You may have to restart Apache to get it to pick up any changes in configuration. You can also use PHP info to check to see if the module is being loaded.

The rules in ``.htaccess`` aren’t being obeyed.

In your virtual host configuration settings (which may be contained within httpd.conf), change the AllowOverride setting so that it reads:

AllowOverride all

This will tell Apache to pick up the mod_rewrite rules from .htaccess.

Elgg is not installed in the root of your web directory (ex: http://example.org/elgg/ instead of http://example.org/)

The install script redirects me to “action” when it should be “actions”¶

This is a problem with your mod_rewrite setup. DO NOT, REPEAT, DO NOT change any directory names!

I installed in a subdirectory and my install action isn’t working!¶

If you installed Elgg so that it is reached with an address like http://example.org/mysite/ rather than http://example.org/, there is a small chance that the rewrite rules in .htaccess will not be processed correctly. This is usually due to using an alias with Apache. You may need to give mod_rewrite a pointer to where your Elgg installation is.

Open up .htaccess in a text editor
Where prompted, add a line like RewriteBase /path/to/your/elgg/installation/ (Don’t forget the trailing slash)
Save the file and refresh your browser.

Please note that the path you are using is the web path, minus the host.

For example, if you reach your elgg install at http://example.org/elgg/, you would set the base like this:

RewriteBase /elgg/

Please note that installing in a subdirectory does not require using RewriteBase. There are only some rare circumstances when it is needed due to the set up of the server.

I did everything! mod_rewrite is working fine, but still the 404 error¶

Maybe there is a problem with the file .htaccess. Sometimes the elgg install routine is unable to create one and unable to tell you that. If you are on this point and tried everything that is written above:

check if it is really the elgg-created .htaccess (not only a dummy provided from the server provider)
if it is not the elgg provided htaccess file, use the htaccess_dist (rename it to .htaccess)

I get an error message that the rewrite test failed after the requirements check page¶

I get the following messages after the requirements check step (step 2) of the install:

We think your server is running the Apache web server.

The rewrite test failed and the most likely cause is that AllowOverride is not set to All for Elgg’s directory. This prevents Apache from processing the .htaccess file which contains the rewrite rules.

A less likely cause is Apache is configured with an alias for your Elgg directory and you need to set the RewriteBase in your .htaccess. There are further instructions in the .htaccess file in your Elgg directory.

After this error, everinteraction with the web interface results in a error 500 (Internal Server Error)

This is likely caused by not loading the “filter module by un-commenting the

#LoadModule filter_module modules/mod_filter.so

line in the “httpd.conf” file.

the Apache “error.log” file will contain an entry similar to:

… .htaccess: Invalid command ‘AddOutputFilterByType’, perhaps misspelled or defined by a module not included in the server configuration

There is a white page after I submit my database settings¶

Check that the Apache mysql module is installed and is being loaded.

I’m getting a 404 error with a really long url¶

If you see a 404 error during the install or on the creation of the first user with a url like: http://example.com/homepages/26/d147515119/htdocs/elgg/action/register that means your site url is incorrect in your sites_entity table in your database. This was set by you on the second page of the install. Elgg tries to guess the correct value but has difficulty with shared hosting sites. Use phpMyAdmin to edit this value to the correct base url.

I am having trouble setting my data path¶

This is highly server specific so it is difficult to give specific advice. If you have created a directory for uploading data, make sure your http server can access it. The easiest (but least secure) way to do this is give it permissions 777. It is better to give the web server ownership of the directory and limit the permissions.

The top cause of this issue is PHP configured to prevent access to most directories using open_basedir. You may want to check with your hosting provider on this.

Make sure the path is correct and ends with a /. You can check the path in your database in the datalists table.

If you only have ftp access to your server and created a directory but do not know the path of it, you might be able to figure it out from the www file path set in your datalists database table. Asking for help from your hosting help team is recommended at this stage.

I can’t validate my admin account because I don’t have an email server!¶

While it’s true that normal accounts (aside from those created from the admin panel) require their email address to be authenticated before they can log in, the admin account does not.

Once you have registered your first account you will be able to log in using the credentials you have provided!

I have tried all of these suggestions and I still cannot install Elgg¶

It is possible that during the process of debugging your install you have broken something else. Try doing a clean install:

drop your elgg database
delete your data directory
delete the Elgg source files
start over

If that fails, seek the help of the Elgg community. Be sure to mention what version of Elgg you are installing, details of your server platform, and any error messages that you may have received including ones in the error log of your server.

Developer Overview¶

This is a quick developer introduction to Elgg. It covers the basic approach to working with Elgg as a framework, and mentions some of the terms and technologies used.

See the Developer Guides for tutorials or the Design Docs for in-depth discussion on design.

Database and Persistence¶

Elgg uses MySQL 5.5 or higher for data persistence, and maps database values into Entities (a representation of an atomic unit of information) and Extenders (additional information and descriptions about Entities). Elgg supports additional information such as relationships between Entities, activity streams, and various types of settings.

Plugins¶

Plugins change the behavior or appearance of Elgg by overriding views, or by handling events and plugin hooks. All changes to an Elgg site should be implemented through plugins to ensure upgrading core is easy.

Actions¶

Actions are the primary way users interact with an Elgg site. Actions are registered by plugins.

Events and Plugin Hooks¶

Events and Plugin Hooks are used in Elgg Plugins to interact with the Elgg engine under certain circumstances. Events and hooks are triggered at strategic times throughout Elgg’s boot and execution process, and allows plugins to modify or cancel the default behavior.

Views¶

Views are the primary presentation layer for Elgg. Views can be overridden or extended by Plugins. Views are categories into a Viewtype, which hints at what sort of output should be expected by the view.

JavaScript¶

Elgg uses an AMD-compatible JavaScript system provided by RequireJs. Bundled with Elgg are jQuery, jQuery UI, jQuery Form, jQuery jeditable, and jQuery UI Autocomplete.

Plugins can load their own JS libs.

Internationalization¶

Elgg’s interface supports multiple languages, and uses Transifex for translation.

Caching¶

Elgg uses two caches to improve performance: a system cache and SimpleCache.

3rd party libraries¶

The use of 3rd party libraries in Elgg is managed by using Composer dependencies. Examples of 3rd party libraries are jQuery, RequireJs or Zend mail.

To get a list of all the Elgg dependencies check out the Packagist page for Elgg.

Database Seeding¶

Elgg provides some base database seeds to populate the database with entities for testing purposes.

You can run the following commands to seed and unseed the database.

..code::sh

# seed the database composer database:seeder:seed

# unseed the database composer database:seeder:unseed

Administrator Guides¶

Best practices for effectively managing an Elgg-based site.

Getting Started¶

You have installed Elgg and worked through any potential initial issues. What now? Here are some suggestions on how to to familiarize yourself with Elgg.

Focus first on core functionality¶

When you’re new to Elgg, it’s best to explore the stock features in core and its bundled plugins before installing any third party plugins. It’s tempting install every interesting plugin from the community site, but exploring the core features builds a familiarity with Elgg’s expected behavior, and prevents introducing any confusing bugs from third party plugin into your new Elgg network.

Elgg installs with a basic set of social network plugins activated: blogs, social bookmarking, files, groups, likes, message boards, wiki-like pages, user profiles, and microblogging. To change the plugins that are activated, log in as an admin user, then use the topbar to browse to Administration, then to Plugins on the right sidebar.

Note

The user you create during installation is an admin user.

Create test users¶

Users can be created two ways in stock Elgg:

Complete the signup process using a different email address and username. (Logout first or use a different browser!)

Add a user through the Admin section by browsing to Administration -> Users -> Add New User.

Note

Users that self-register must validate their account through email before they can log in. Users that an admin creates are already validated.

Explore user functionality¶

Use your test users to create blogs, add widgets to your profile or dashboard, post to the Wire (microblogging), and create pages (wiki-like page creation). Investigate the Settings on the topbar. This is where a user sets notification settings and configures tools (which will be blank because none of the default plugins add controls here).

Explore admin functionality¶

All of the admin controls are found by clicking Administration in the topbar. The has a dashboard with a widget that explains the various sections. Change options in the Configure menu to change how Elgg looks and acts.

Extending Elgg¶

After exploring what Elgg can do out of the box, install some themes and plugins. You can find many plugins and themes at the community site that have been developed by third parties. These plugins do everything from changing language strings, to adding chat, to completely redesigning Elgg’s interface. Because these plugins are not official, be certain to check the comments to make sure you only install well-written plugins by high quality developers.

Upgrading Elgg¶

Switch a live site to a new version of Elgg.

If you’ve written custom plugins, you should also read the developer guides for information on upgrading plugin code for the latest version of Elgg.

Advice¶

Back up your database and code
Mind any version-specific comments below
Upgrade only one minor version at a time (1.6 => 1.7, then 1.7 => 1.8)
Try out the new version on a test site before doing an upgrade
Report any problems in plugins to the plugin authors
If you are a plugin author you can report any backwards-compatibility issues to GitHub

Basic instructions¶

Log in as an admin to your site
Disable caching in Advanced Settings
Back up your database, data directory, and code
Download the new version of Elgg from http://elgg.org
Update the files
- If doing a patch upgrade (1.9.x), overwrite your existing files with the new version of Elgg
- If doing a minor upgrade (1.x), replace the existing core files completely
Merge any new changes to the rewrite rules
- For Apache from install/config/htaccess.dist into .htaccess
- For Nginx from install/config/nginx.dist into your server configuration (usually inside /etc/nginx/sites-enabled)
Merge any new changes from settings.example.php into settings.php
Visit http://your-elgg-site.com/upgrade.php

Note

Any modifications should have been written within plugins, so that they are not lost on overwriting. If this is not the case, take care to maintain your modifications.

From 2.2 to 2.3¶

PHP Version¶

PHP 5.5 has reached end of life in July 2016. To ensure that Elgg sites are secure, we now require PHP 5.6 for new installations.

Existing installations can continue using PHP 5.5 until Elgg 3.0.

In order to upgrade Elgg to 2.3 using composer while using PHP 5.5, you may need to use --ignore-platform-reqs flag.

Tests¶

PHPUnit bootstrap is deprecated by composer autoloader: Tests should no longer bootstrap themselves using /engine/tests/phpunit/bootstrap.php. Instead, tests should extend \Elgg\TestCase.

Some core files now sniff if PHPUNIT_ELGG_TESTING_APPLICATION constant is set to determine whether Elgg is being bootstrapped for PHPUnit tests. phpunit.xml configuration needs to updated to include this constant definition.

PHPUnit bootstrap no longer sets global $CONFIG. Tests should use _elgg_services()->config instead.

Core and tests no longer use private global values in $_ELGG->view_path and $_ELGG->allowed_ajax_views

Schema¶

The database GUID columns need to be aligned. In the admin section an upgrade is available to handle this. Please make sure you have a backup available

From 1.x to 2.0¶

Removed plugins¶

The following plugins are no longer bundled with Elgg core:

categories (https://github.com/elgg/categories)

zaudio (https://github.com/elgg/zaudio)

IE-specific workarounds have been dropped¶

Several views (css/ie, css/ie7, css/ie8, etc.) as well as conditional comments have been discarded now that IE10+ browsers are more standards-compliant. If you need browser support farther back than that, you will need to find or build a plugin that introduces its own compatibility layer or polyfills.

Update your webserver config¶

URL paths like cache/* and rewrite.php now use the main front controller script. You must remove these rewrite rules from your webserver config (e.g. .htaccess).

Also remove the rules for paths like export/*; these endpoints have been removed.

Settings location¶

After upgrading, move your settings.php file from engine/ to elgg-config/.

From 1.10 to 1.11¶

Breaking changes¶

In versions 1.9 and 1.10, names and values for metadata and annotations were not correctly trimmed for whitespace. Elgg 1.11 correctly trims these strings and updates the database to correct existing strings. If your plugin uses metadata or annotations with leading or trailing whitespace, you will need to update the plugin to trim the names and values. This is especially important if you are using custom SQL clauses or have hard-coded metastring IDs, since the update might change metastring IDs.

From 1.8 to 1.9¶

Elgg 1.9 is a much lighter upgrade than 1.8 was.

Breaking changes¶

Plugins and themes written for 1.8 are expected to be compatible with 1.9 except as it pertains to comments, discussion replies, and notifications. Please report any backwards compatibility issues besides those just listed.

Upgrade steps¶

There are several data migrations involved, so it is especially important that you back up your database and data directory before performing the upgrade.

Download the new version and copy these files from the existing 1.8 site:

.htaccess

engine/settings.php

any 3rd-party plugin folders in the mod directory

Then replace the old installation directory with the new one. This way you are guaranteed to get rid of obsolete files which might cause problems if left behind.

Follow the basic instructions listed above.

After you’ve visited upgrade.php, go to the admin area of your site. You should see a notification that you have pending upgrades. Click the link in the notification bar to view and run the upgrades.

The new notifications system delivers messages via a minutely cron handler. If you haven’t done so yet, you will need to install and configure crontab on your server. If cron jobs are already configured, note that the scope of available cron periods may have changed and you may need to update your current crontab to reflect these changes.

Time commitment¶

Running all of the listed upgrades took about 1 hour and 15 minutes on the Elgg community site which at the time had to migrate:

~75,000 discussion replies

~75,000 comments

~75,000 data directories

You should take this only as a ballpark estimate for your own upgrade. How long it takes will depend on how large your site is and how powerful your servers are.

From 1.7 to 1.8¶

Elgg 1.8 is the biggest leap forward in the development of Elgg since version 1.0. As such, there is more work to update core and plugins than with previous upgrades.

Updating core¶

Delete the following core directories (same level as _graphics and engine):

_css
account
admin
dashboard
entities
friends
search
settings
simplecache
views

Warning

If you do not delete these directories before an upgrade, you will have problems!

Plugins¶

Plugins can modify the behavior of and add new features to Elgg.

Contents

Where to get plugins
The Elgg Community
- Finding Plugins
- Evaluating Plugins
Types of plugins
- Themes
- Language Packs
Installation
Plugin order
Pre-1.8 notes

Where to get plugins ¶

Plugins can be obtained from:

The Elgg Community

Github

Third-party sites (typically for a price)

If no existing plugins meet your needs, you can hire a developer or create your own.

The Elgg Community ¶

Finding Plugins ¶

Sort based on most popular¶

On the community plugin page, you can sort by date uploaded (Filter: Newest) or number of downloads (Filter: Most downloads). Sorting by the number of downloads is a good idea if you are new to Elgg and want to see which plugins are frequently used by other administrators. These will often (but not always) be higher quality plugins that provide significant capabilities.

Use the plugin tag search¶

Next to the filtering control on the plugin page is a search box. It enables you to search by tags. Plugins authors choose the tags.

Look for particular plugin authors¶

The quality of plugins varies substantially. If you find a plugin that works well on your site, you can check what else that plugin author has developed by clicking on their name when viewing a plugin.

Evaluating Plugins ¶

Look at the comments and ratings¶

Before downloading and using a plugin, it is always a good idea to read through the comments that others have left. If you see people complaining that the plugin does not work or makes their site unstable, you probably want to stay away from that plugin. The caveat to that is that sometimes users ignore installation instructions or incorrectly install a plugin and then leave negative feedback. Further, some plugin authors have chosen to not allow comments.

Install on a test site¶

If you are trying out a plugin for the first time, it is a bad idea to install it on your production site. You should maintain a separate test site for evaluating plugins. It is a good idea to slowly roll out new plugins to your production site even after they pass your evaluation on your test site. This enables you to isolate problems introduced by a new plugin.

Types of plugins ¶

Themes ¶

Themes are plugins that modify the look-and-feel of your site. They generally include stylesheets, client-side scripts and views that alter the default presentation and behavior of Elgg.

Language Packs ¶

Language packs are plugins that provide support for other languages.

Language packs can extend and include translations for language strings found in the core, core plugins and/or third-party plugins.

Some of the language packs are already included in the core, and can be found in languages directory off Elgg’s root directory. Individual plugins tend to include their translations under the languages directory within the plugin’s root.

This structure makes it easy to create new language packs that supercede existing language strings or add support for new languages.

Installation ¶

All plugins reside in the mod directory of your Elgg installation.

To install a new plugin:

extract (unzip) contents of the plugin distribution package
copy/FTP the extracted folder into the mod directory of your Elgg installation, making sure that manifest.xml and start.php are directly under the plugin directory (e.g. if you were to install a plugin called my_elgg_plugin, plugin’s manifest would need to be found at mod/my_elgg_plugin/manifest.xml)
activate the plugin from your admin panel

To activate a plugin:

Log in to your Elgg site with your administrator account
Go to Administration -> Configure -> Plugins
Find your plugin in the list of installed plugins and click on the ‘enable’ button.

Plugin order ¶

Plugins are loaded according to the order they are listed on the Plugins page. The initial ordering after an install is more or less random. As more plugins are added by an administrator, they are placed at the bottom of the list.

Some general rules for ordering plugins:

A theme plugin should be last or at least near the bottom
A plugin that modifies the behavior of another plugin should be lower in the plugin list

Pre-1.8 notes ¶

In Elgg 1.7 and below, the interface for managing installed plugins is located at Administration -> Tool Administration.

Performance¶

Make your site run as smoothly and responsively as possible.

Contents

Can Elgg scale to X million users?
Measure first
Tune MySQL
Enable caching
Hosting
- Memory, CPU and bandwidth
- Configuration
Check for poorly-behaved plugins
Use client-rendered HTML

Can Elgg scale to X million users?¶

People often ask whether Elgg can scale to large installations.

First, we might stop and ask, “where are you planning to get all those users?” Seriously, though, this is a really interesting problem. Making Elgg scale is, if anything, an issue of technical engineering. It’s interesting but more or less a solved problem. Computer science doesn’t work differently for Elgg than for Google, for example. Getting millions of users? That’s like the Holy Grail of the entire tech industry.

Second, as with most things in life, the answer is “it depends”:

How active are your users?

What hardware is Elgg running on?

Are your plugins behaving well?

Improving the efficiency of the Elgg engine is an ongoing project, although there are limits to the amount that any script can do.

If you are serious about scalability you will probably want to look at a number of things yourself.

Measure first ¶

There is no point in throwing resources at a problem if you don’t know:

what the problem is

what resources the problem needs

where those resources are needed

Invest in some kind of profiling to tell you where your bottleneck is, especially if you’re considering throwing significant money at a problem.

Tune MySQL ¶

Elgg makes extensive use of the back end database, making many trips on each pageload. This is perfectly normal and a well configured database server will be able to cope with thousands of requests per second.

Here are some configuration tips that might help:

Make sure that MySQL is configured to use an appropriate my.cnf for the size of your website.

Increase the amount of memory available to PHP and MySQL (you will have to increase the amount of memory available to the php process in any case)

Enable caching ¶

Generally, if a program is slow, that is because it is repeatedly performing an expensive computation or operation. Caching allows the system to avoid doing that work over and over again by using memory to store the results so that you can skip all the work on subsequent requests. Below we discuss several generally-available caching solutions relevant to Elgg.

Simplecache ¶

By default, views are cached in the Elgg data directory for a given period of time. This removes the need for a view to be regenerated on every page load.

This can be disabled by setting $CONFIG->simplecache_enabled = false; For best performance, make sure this value is set to true.

This does lead to artifacts during development if you are editing themes in your plugin as the cached version will be used in preference to the one provided by your plugin.

The simple cache can be disabled via the administration menu. It is recommended that you do this on your development platform if you are writing Elgg plugins.

This cache is automatically flushed when a plugin is enabled, disabled or reordered, or when upgrade.php is executed.

For best performance, you can also create a symlink from /cache/ in your www root dir to the /views_simplecache/ directory in the data directory you configured when you installed Elgg:

cd /path/to/wwwroot/
ln -s /path/to/dataroot/views_simplecache/ cache

If your webserver supports following symlinks, this will serve files straight off disk without booting up PHP each time.

For security reasons, some webservers (e.g. Apache in version 2.4) might follow the symlinks by default only if the owner of the symlink source and target match. If the cache symlink fails to work on your server, you can change the owner of the cache symlink itself (and not the /views_simplecache/ directory) with

cd /path/to/wwwroot/
chown -h wwwrun:www cache

In this example it’s assumed that the /views_simplecache/ directory in the data directory is owned by the wwwrun account that belongs to the www group. If this is not the case on your server, you have to modify the chown command accordingly.

System cache ¶

The location of views are cached so that they do not have to be discovered (profiling indicated that page load took a non-linear amount of time the more plugins were enabled due to view discovery). Elgg also caches information like the language mapping and class map.

This can be disabled by setting $CONFIG->system_cache_enabled = false; For best performance, make sure this value is set to true.

This is currently stored in files in your dataroot (although later versions of Elgg may use memcache). As with the simple cache it is flushed when a plugin is enabled, disabled or reordered, or when upgrade.php is executed.

The system cache can be disabled via the administration menu, and it is recommended that you do this on your development platform if you are writing Elgg plugins.

Boot cache (experimental)¶

Elgg has the ability to cache numerous resources created and fetched during the boot process. To enable this cache you must set a TTL in your settings.php file: $CONFIG->boot_cache_ttl = 10;

A small TTL is recommended because it brings all the benefits of caching under load while reducing the harm if Elgg’s cache invalidation strategy should miss something.

Database query cache ¶

For the lifetime of a given page’s execution, a cache of all SELECT queries is kept. This means that for a given page load a given select query will only ever go out to the database once, even if it is executed multiple times. Any write to the database will flush this cache, so it is advised that on complicated pages you postpone database writes until the end of the page or use the execute_delayed_* functionality. This cache will be automatically cleared at the end of a page load.

You may experience memory problems if you use the Elgg framework as a library in a PHP CLI script. This can be disabled by setting $CONFIG->db_disable_query_cache = true;

Etags and Expires headers ¶

These technologies tell your users’ browsers to cache static assets (CSS, JS, images) locally. Having these enabled greatly reduces server load and improves user-perceived performance.

Use the Firefox yslow plugin or Chrome DevTools Audits to confirm which technologies are currently running on your site.

If the static assets aren’t being cached:

Verify that you have these extensions installed and enabled on your host
Update your .htaccess file, if you are upgrading from a previous version of Elgg
Enable Simplecache, which turns select views into browser-cacheable assets

Memcache ¶

Memcache is a generic caching technology developed by Brad Fitzpatrick for LiveJournal.

Warning

SUPPORT FOR MEMCACHE IS EXPERIMENTAL AND MAY BE CHANGED.

Installation requirements:

php5-memcache
memcached

Configuration:

Uncomment and populate the following sections in settings.php

$CONFIG->memcache = true;

$CONFIG->memcache_servers = array (
    array('server1', 11211),
    array('server2', 11211)
);

Optionaly if you run multiple Elgg installations but use ony one Memcache server, you may want to add a namespace prefix. In order to do this, uncomment the following line

$CONFIG->memcache_namespace_prefix = '';

Squid ¶

We have had good results by using Squid to cache images for us.

Bytecode caching ¶

There are numerous PHP code caches available on the market. These speed up your site by caching the compiled byte code from your script meaning that your server doesn’t have to compile the PHP code each time it is executed.

Direct file serving ¶

If your server can be configured to support the X-Sendfile or X-Accel headers, you can configure it to be used in settings.php. This allows your web server to directly stream files to the client instead of using PHP’s readfile().

Hosting ¶

Don’t expect to run a site catering for millions of users on a cheap shared host. You will need to have your own host hardware and access over the configuration, as well as lots of bandwidth and memory available.

Memory, CPU and bandwidth ¶

Due to the nature of caching, all caching solutions will require memory. It is a fairly cheap return to throw memory and CPU at the problem.

On advanced hardware it is likely that bandwidth is going to be your bottleneck before the server itself. Ensure that your host can support the load you are suggesting.

Configuration ¶

Lastly, take a look at your configuration as there are a few gotchas that can catch people.

For example, out of the box, Apache can handle quite a high load. However, most distros of Linux come with mysql configured for small sites. This can result in Apache processes getting stalled waiting to talk to one very overloaded MySQL process.

Check for poorly-behaved plugins ¶

Plugins can be programmed in a very naive way and this can cause your whole site to feel slow.

Try disabling some plugins to see if that noticeably improves performance. Once you’ve found a likely offender, go to the original plugin author and report your findings.

Use client-rendered HTML ¶

We’ve found that at a certain point, much of the time spent on the server is simply building the HTML of the page with Elgg’s views system.

It’s very difficult to cache the output of templates since they can generally take arbitrary inputs. Instead of trying to cache the HTML output of certain pages or views, the suggestion is to switch to an HTML-based templating system so that the user’s browser can cache the templates themselves. Then have the user’s computer do the work of generating the output by applying JSON data to those templates.

This can be very effective, but has the downside of being significant extra development cost. The Elgg team is looking to integrate this strategy into Elgg directly, since it is so effective especially on pages with repeated or hidden content.

Cron¶

Cron is a program available on Unix-based operating systems that enables users to run commands and scripts at set intervals or at specific times.

Elgg’s cron handler allows administrators and plugin developers to setup jobs that need to be executed at set intervals.

Most common examples of cron jobs in Elgg include:

sending out queued notifications

rotating the system log in the database

collecting garbage in the database (compacting the database by removing entries that are no longer required)

Currently, Elgg supports the following hooks:

minute - Run every minute

fiveminute - Run every 5 minutes

fifteenmin - Run every 15 minutes

halfhour - Run every 30 minutes

hourly - Run every hour

daily - Run every day

weekly - Run every week

monthly - Run every month

yearly - Run every year

Note

reboot cron hook has been deprecated and should not be used

How does it work?¶

Elgg activates its cron handler when particular cron pages are loaded. As an example, loading http://example.com/cron/hourly/ in a web browser activates the hourly hook. To automate this, cron jobs are setup to hit those pages at certain times. This is done by setting up a crontab which is a configuration file that determines what cron jobs do and at what interval.

Installation¶

The crontab needs to specify a script or command that will hit the Elgg cron pages. Two commonly available programs for this are GET and wget. You will need to determine the location of one of these on your server. Your crontab also needs to specify the location of your website.

# Crontab example.
#
# This file is an example of triggering Elgg cron events. It hits a URL to
# trigger the events. For testing, you can simulate the cronjob by loading the
# URL in a browser.
#
# See http://learn.elgg.org/en/stable/admin/cron.html for more information
#

# Location of your site (don't forget the trailing slash!)
ELGG='http://www.example.com/'

# Location of lwp-request
LWPR='/usr/bin/lwp-request'

# Make GET request and discard content
GET="$LWPR -m GET -d"

# The crontab
# Don't edit below this line unless you know what you are doing
* * * * * $GET ${ELGG}cron/minute/
*/5 * * * * $GET ${ELGG}cron/fiveminute/
15,30,45,59 * * * * $GET ${ELGG}cron/fifteenmin/
30,59 * * * * $GET ${ELGG}cron/halfhour/
@hourly $GET ${ELGG}cron/hourly/
@daily $GET ${ELGG}cron/daily/
@weekly $GET ${ELGG}cron/weekly/
@monthly $GET ${ELGG}cron/monthly/
@yearly $GET ${ELGG}cron/yearly/
# reboot is deprecated and probably doesn't work
@reboot $GET ${ELGG}cron/reboot/

In the above example, change the ELGG and GET variables to match you server setup. If you have SSH access to your Linux servers, type crontab -e and add your crontab configuration. If you already have a crontab configured, you will have to merge Elgg information into it. If you don’t have SSH access, you will have to use a web-based configuration tool. This will vary depending on hosting provider.

If you choose the wget utility, you might want to consider these flags:

--output-document or -O to specify the location of the concatenated output file. For example, under Debian: /usr/bin/wget --output-document=/dev/null. If you don’t do that, a new file will be created for each cron page load in the home directory of the cron user.

--spider to prevent the cron page from being downloaded.

On Windows servers, there is a number of cron emulators available.

For information on setting up cron jobs using cPanel see cPanel Docs.

In the command field, enter the appropriate link of the cron page. For example, for a weekly cron job, enter the command as http://www.example.com/cron/weekly/.

To see if your cron jobs are running, visit Statistics > Cron in your Elgg admin panel.

Backup and Restore¶

Contents

Introduction
- Why
- What
- Assumptions
Creating a usable backup - automatically
Restoring from backup
Congratulations!
Related

Introduction ¶

Why ¶

Shared hosting providers typically don’t provide an automated way to backup your Elgg installation. This article will address a method of accomplishing this task.

In IT there are often many ways to accomplish the same thing. Keep that in mind. This article will explain one method to backup and restore your Elgg installation on a shared hosting provider that uses the CPanel application. However, the ideas presented here can be tailored to other applications as well. The following are typical situations that might require a procedure such as this:

Disaster Recovery
Moving your Elgg site to a new host
Duplicating an installation

What ¶

Topics covered:

Full backups of the Elgg directories and MySQL databases are performed daily (automated)
The backups are sent to an off-site location via FTP (automated)
The local backups are deleted after successful transfer to the off-site location (automatic)
Five days of backups will be maintained (automated)
Restoration of data to the new host (manual)

This process was composed with assistance from previous articles in the Elgg documentation wiki.

Assumptions ¶

The following assumptions have been made:

The Elgg program directory is /home/userx/public_html
The Elgg data directory is /home/userx/elggdata
You’ve created a local directory for your backups at /home/userx/sitebackups
You have an off-site FTP server to send the backup files to
The directory that you will be saving the off-site backups to is /home/usery/sitebackups/
You will be restoring the site to a second shared hosting provider in the /home/usery/public_html directory

Important

Be sure to replace userx, usery, http://mynewdomain.com and all passwords with values that reflect your actual installation!

Creating a usable backup - automatically ¶

Customize the backup script ¶

The script that you will use can be found here .

Just copy the script to a text file and name the file with a .pl extension. You can use any text editor to update the file.

Change the following to reflect your directory structure:

# ENTER THE PATH TO THE DIRECTORY YOU WANT TO BACKUP, NO TRAILING SLASH
$directory_to_backup = '/home/userx/public_html';
$directory_to_backup2 = '/home/userx/elggdata';
# ENTER THE PATH TO THE DIRECTORY YOU WISH TO SAVE THE BACKUP FILE TO, NO TRAILING SLASH
$backup_dest_dir = '/home/userx/sitebackups';

Change the following to reflect your database parameters:

# MYSQL BACKUP PARAMETERS
$dbhost = 'localhost';
$dbuser = 'userx_elgg';
$dbpwd = 'dbpassword';
# ENTER DATABASE NAME
$database_names_elgg = 'userx_elgg';

Change the following to reflect your off-site FTP server parameters:

# FTP PARAMETERS
$ftp_host = "FTP HOSTNAME/IP";
$ftp_user = "ftpuser";
$ftp_pwd = "ftppassword";
$ftp_dir = "/";

Save the file with the .pl extension (for the purposes of this article we will name the file: elgg-ftp-backup-script.pl) and upload it to the following directory /home/userx/sitebackups

Be aware that you can turn off FTP and flip a bit in the script so that it does not delete the local backup file in the event that you don’t want to use off-site storage for your backups.

Configure the backup Cron job ¶

Login to your CPanel application and click on the “Cron Jobs” link. In the Common Settings dropdown choose “Once a day” and type the following in the command field /usr/bin/perl /home/userx/sitebackups/elgg-ftp-backup-script.pl

Click on the “Add New Cron Job” button. Daily full backups are now scheduled and will be transferred off-site.

Configure the cleanup Cron job ¶

If you are sending your backups, via FTP, to another shared hosting provider that uses the CPanel application or you’ve turned off FTP altogether you can configure your data retention as follows.

Login to your CPanel application for your FTP site, or locally if you’re not using FTP, and click on the “Cron Jobs” link. In the Common Settings dropdown choose “Once a day” and type the following in the command field find /home/usery/sitebackups/full_* -mtime +4 -exec rm {} \;

The -mtime X parameter will set the number of days to retain backups. All files older than x number of days will be deleted. Click on the “Add New Cron Job” button. You have now configured your backup retention time.

Restoring from backup ¶

Prepare your backup files ¶

The assumption is that you’re restoring your site to another shared hosting provider with CPanel.

When the script backed the files up the original directory structure was maintained in the zip file. We need to do a little cleanup. Perform the following:

Download the backup file that you wish to restore from
Extract the contents of the backup file
Drill down and you will find your site backup and SQL backup. Extract both of these. You will then have:
- a MySQL dump file with a .sql extension
- another directory structure with the contents of:
  
  /home/userx/public_html
  
  /home/userx/elggdata
Repackage the contents of the /home/userx/public_html directory as a zip file so that the files are in the root of the zip file
- The reason for doing this is simple. It’s much more efficient to upload one zip file than it is to ftp the contents of the /home/userx/public_html directory to your new host.
Repackage the contents of the /home/userx/elggdata directory as a zip file so that the files are in the root of the zip file

You should now have the following files:

the .sql file
the zip file with the contents of /home/userx/public_html in the root
the zip file with the contents of /home/userx/elggdata in the root

Restore the files ¶

This is written with the assumption that you’re restoring to a different host but maintaining the original directory structure. Perform the following:

Login to the CPanel application on the host that you wish to restore the site to and open the File Manager.
Navigate to /home/usery/public_html
- Upload the zip file that contains the /home/userx/public_html files
- Extract the zip file
  
  You should now see all of the files in /home/usery/public_html
- Delete the zip file
Navigate to /home/usery/elggdata
- Upload the zip file that contains the /home/userx/elggdata files
- Extract the zip file
  
  You should now see all of the files in /home/usery/elggdata
- Delete the zip file

Program and data file restoration is complete

Restore the MySQL Database ¶

Note

Again, the assumption here is that you’re restoring your Elgg installation to a second shared hosting provider. Each shared hosting provider prepends the account holder’s name to the databases associated with that account. For example, the username for our primary host is userx so the host will prepend userx_ to give us a database name of userx_elgg. When we restore to our second shared hosting provider we’re doing so with a username of usery so our database name will be usery_elgg. The hosting providers don’t allow you to modify this behavior. So the process here isn’t as simple as just restoring the database from backup to the usery account. However, having said that, it’s not terribly difficult either.

Edit the MySQL backup ¶

Open the .sql file that you extracted from your backup in your favorite text editor. Comment out the following lines with a hash mark:

#CREATE DATABASE /*!32312 IF NOT EXISTS*/ `userx_elgg` /*!40100 DEFAULT CHARACTER SET latin1 */;
#USE `userx_elgg`;

Save the file.

Create the new database ¶

Perform the following:

Login to the CPanel application on the new host and click on the “MySQL Databases” icon
- Fill in the database name and click the “create” button. For our example we are going to stick with elgg which will give us a database name of usery_elgg
- You can associate an existing user with the new database, but to create a new user you will need to:
  
  Go to the “Add New User” section of the “MySQL Databases” page
  
  Enter the username and password. For our example we’re going to keep it simple and use elgg once again. This will give us a username of usery_elgg
- Associate the new user with the new database
  
  Go to the “Add User To Database” section of the “MySQL Databases” page. Add the usery_elgg user to the usery_elgg database
  
  Select “All Privileges” and click the “Make Changes” button

Restore the production database ¶

Now it’s time to restore the MySQL backup file by importing it into our new database named “usery_elgg”.

Login to the CPanel application on the new host and click on the “phpMyAdmin icon
- Choose the usery_elgg database in the left hand column
- Click on the “import” tab at the top of the page
- Browse to the .sql backup on your local computer and select it
- Click the “Go” button on the bottom right side of the page

You should now see a message stating that the operation was successful

Bringing it all together ¶

The restored elgg installation knows nothing about the new database name, database username, directory structure, etc. That’s what we’re going to address here.

Edit /public_html/elgg-config/settings.php on the new hosting provider to reflect the database information for the database that you just created.

// Database username
$CONFIG->dbuser = 'usery_elgg';

// Database password
$CONFIG->dbpass = 'dbpassword';

// Database name
$CONFIG->dbname = 'usery_elgg';

// Database server
// (For most configurations, you can leave this as 'localhost')
$CONFIG->dbhost = 'localhost';

Upload the settings.php file back to the new host - overwriting the existing file.

Open the phpMyAdmin tool on the new host from the CPanel. Select the usery_elgg database on the left and click the SQL tab on the top of the page. Run the following SQL queries against the usery_elgg database:

Change the installation path

UPDATE `elgg_datalists` SET `value` = "/home/usery/public_html/grid/" WHERE `name` = "path";

Change the data directory

UPDATE `elgg_datalists` SET `value` = "/home/usery/elggdata/" WHERE `name` = "dataroot";

Change the site URL (if this has changed)

UPDATE `elgg_sites_entity` SET `url` = "http://mynewdomain.com";

Change the filestore data directory

UPDATE elgg_metastrings set string = '/home/usery/elggdata/' WHERE id = (SELECT value_id from elgg_metadata where name_id = (SELECT * FROM (SELECT id FROM elgg_metastrings WHERE string = 'filestore::dir_root') as ms2) LIMIT 1);

Finalizing the new installation ¶

Run the upgrade script by visiting the following URL: http://mynewdomain.com/upgrade.php . Do this step twice - back to back.

Update your DNS records so that your host name resolves to the new host’s IP address if this is a permanent move.

Congratulations!¶

If you followed the steps outlined here you should now have a fully functional copy of your primary Elgg installation.

Getting Help¶

Having a problem with Elgg? The best way to get help is to ask at the Community Site. This site is community supported by a large group of volunteers. Here are a few tips to help you get the help you need.

Contents

Getting help
Guidelines
Good Ideas

Getting help ¶

Don’t be a Help Vampire ¶

We were all newbies at one time, but we can all learn. Not showing that you are making attempts to learn on your own or do your own research is off putting for those helping. Also, very generic questions like “How do I build a forum?” are almost impossible to answer.

Search first¶

Be sure to search the documentation (this site), the Community Site, and Google before asking a question. New users to Elgg frequently have the same questions, so please search. People are less inclined to reply to a post that has been answered many other times or that can be answered easily by Googling.

Ask once¶

Posting the same questions in multiple places makes it hard to answer you. Ask your question in one place only. Duplicate questions may be moderated.

Include Elgg Version¶

Different versions of Elgg have different features (and different bugs). Including the version of Elgg that you are using will help those helping you.

Have a reasonable profile¶

Profiles that look like spam or have silly names will often be ignored. Joviality is fine, but people are more likely to help Michael than 1337elggHax0r.

Post in the appropriate forum¶

Check to make sure you’re posting in the right forum. If you have a question about creating a plugin, don’t post to the Elgg Feedback forum. If you need help installing Elgg, post to Technical Support instead of the Theming group.

Use a descriptive topic title¶

Good topic titles concisely describe your problem or question. Bad topic titles are vague, contain all capital letters, and excessive punctuation.

Good title: “White screen after upgrading to 1.7.4.”

Bad title: “URGENT!!!!! site broke ;-( losing money help!!!!!!!!!!!”

Be detailed¶

Include as many details about your problem as possible. If you have a live site, include a link. Be forthcoming if community members might ask for more information. We can’t help you if you won’t give any details!

Keep it public¶

This is a public forum for the good of the Elgg project. Keep posts public. There’s no reason for anyone to ask you to send a private message or email. Likewise, there’s no reason to ask anyone to send a private email to you. Post in the public.

Guidelines ¶

In addition to the site-wide Terms and Policies, following these guidelines keeps our community site useful and safe for everyone.

Content¶

All content must be safe for work: PG in the US and UK. If your Elgg site has adult content and you have been asked to post a link, please mark it NSFW (Not Safe For Work) so people know.

Excessive swearing in any language will not be tolerated.

Mood¶

Working with technical problems can be frustrating. Please keep the community site free of frustration. If you’re feeling anxious, take a step away and do something else. Threatening or attacking community members, core developers, or plugin developers will not help solve your problem and will likely get you banned.

Advertising¶

Advertising is not allowed. Posts with any sort of advertising will be moderated.

Asking for money / Offering to pay¶

Don’t ask for money on the community site. Likewise, don’t offer to pay for answers. If you are looking for custom development, post to the Professional Services group. Posts asking for money or recommending a commercial plugin may be moderated.

Links¶

If you’re having a problem with a live site, please provide a link to it.

That said, the community site is not a back linking service or SEO tool. Excessive linking will be moderated and your account may be banned.

Signatures¶

There’s a reason Elgg doesn’t have an option for signatures: they cause clutter and distract from the conversation. Users are discouraged from using signatures on the community site, and signatures with links or advertising will be removed.

Bumping, +1, me too¶

Don’t do it. If your question hasn’t been answered, see the top of this document for tips. These types of post add nothing to the conversation and may be moderated.

Posting Code¶

Long bits of code are confusing to read through in a forums context. Please use http://elgg.pastebin.com to post long bits of code and provide the Paste Bin link instead of directly posting the code.

Good Ideas ¶

Not policies, but good ideas.

Say thanks¶

Did someone help you? Be sure to thank them! The community site is run by volunteers. No one has to help you with your problem. Be sure to show your appreciation!

Give back¶

Have a tip for Elgg? See someone with a similar problem you had? You’ve been there and can help them out, so give them a hand!

Developer Guides¶

Customize Elgg’s behavior with plugins.

Don’t Modify Core¶

Warning

In general, you shouldn’t modify non-config files that come with third-party software like Elgg.

The best way to customize the behavior of Elgg is to install Elgg as a composer dependency and use the root directory to store modifications specific to your application, and alter behavior through the rich Elgg plugin API.

If you’d like to share customizations between sites or even publish your changes as a reusable package for the community, create a plugin using the same plugin APIs and file structure.

It makes it hard to get help¶

When you don’t share the same codebase as everyone else, it’s impossible for others to know what is going on in your system and whether your changes are to blame. This can frustrate those who offer help because it can add considerable noise to the support process.

It makes upgrading tricky and potentially disastrous¶

You will certainly want or need to upgrade Elgg to take advantage of

security patches

new features

new plugin APIs

new stability improvements

performance improvements

If you’ve modified core files, then you must be very careful when upgrading that your changes are not overwritten and that they are compatible with the new Elgg code. If your changes are lost or incompatible, then the upgrade may remove features you’ve added and even completely break your site.

This can also be a slippery slope. Lots of modifications can lead you to an upgrade process so complex that it’s practically impossible. There are lots of sites stuck running old versions software due to taking this path.

It may break plugins¶

You may not realize until much later that your “quick fix” broke seemingly unrelated functionality that plugins depended on.

Summary¶

Resist the temptation

Editing existing files is quick and easy, but doing so heavily risks the maintainability, security, and stability of your site.
When receiving advice, consider if the person telling you to modify core will be around to rescue you if you run into trouble later!
Apply these principle to software in general.

If you can avoid it, don’t modify third party plugins either, for the same reasons: Plugin authors release new versions, too, and you will want those updates.

Plugins¶

Plugins must provide a start.php and manifest.xml file in the plugin root in order to be recognized by Elgg.

start.php¶

The start.php file bootstraps plugin by registering event listeners and plugin hooks.

elgg-plugin.php¶

This optional file is read by Elgg to configure various services, and must return an array if present. It should not be included by plugins and is not guaranteed to run at any particular time. Besides magic constants like __DIR__, its return value should not change.

Syntax¶

Here’s a trivial example configuring view locations via the views key:

<?php

return [
        'views' => [
                'default' => [
                        'file/icon/' => __DIR__ . '/graphics/icons',
                ],
        ],
];

activate.php, deactivate.php¶

The activate.php and deactivate.php files contain procedural code that will run upon plugin activation and deactivation. Use these files to perform one-time events such as registering a persistent admin notice, registering subtypes, or performing garbage collection when deactivated.

manifest.xml¶

Elgg plugins are required to have a manifest.xml file in the root of a plugin.

The manifest.xml file includes information about the plugin itself, requirements to run the plugin, and optional information including where to display the plugin in the admin area and what APIs the plugin provides.

Syntax¶

The manifest file is a standard XML file in UTF-8. Everything is a child of the <plugin_manifest> element.

<?xml version="1.0" encoding="UTF-8" ?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">

The manifest syntax is as follows:

<name>value</name>

Many elements can contain children attributes:

<parent_name>
        <child_name>value</child_name>
        <child_name_2>value_2</child_name_2>
</parent_name>

Required Elements¶

All plugins are required to define the following elements in their manifest files:

id - This has the name as the directory that the plugin uses.
name - The display name of the plugin.
author - The name of the author who wrote the plugin.
version - The version of the plugin.
description - A description of the what the plugin provides, its features, and other relevant information
requires - Each plugin must specify the release of Elgg it was developed for. See the plugin Dependencies page for more information.

Available Elements¶

In addition to the require elements above, the follow elements are available to use:

blurb - A short description of the plugin.
category - The category of the plugin. It is recommended to follow the [[Plugin_Guidelines|plugin guidelines]] and use one of the defined categories. There can be multiple entries.
conflicts - Specifies that the plugin conflicts with a certain system configuration.
copyright - The plugin’s copyright information.
license - The plugin’s license information.
provides - Specifies that this plugin provides the same functionality as another Elgg plugin or a PHP extension.
screenshot - Screenshots of the plugin. There can be multiple entries. See the advanced example for syntax.
suggests - Parallels the requires system, but doesn’t affect if the plugin can be enabled. Used to suggest other plugins that interact or build on the plugin.
website - A link to the website for the plugin.

See also

Plugin Dependencies

Simple Example¶

This manifest file is the bare minimum a plugin must have.

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
        <name>Example Manifest</name>
        <author>Elgg</author>
        <version>1.0</version>
        <description>This is a simple example of a manifest file. In this example, there are not screenshots, dependencies, or additional information about the plugin.</description>

        <requires>
                <type>elgg_release</type>
                <version>1.9</version>
        </requires>
</plugin_manifest>

Advanced example¶

This example uses all of the available elements:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
        <name>Example Manifest</name>
        <author>Brett Profitt</author>
        <version>1.0</version>
        <blurb>This is an example manifest file.</blurb>
        <description>This is a simple example of a manifest file. In this example, there are many options used, including screenshots, dependencies, and additional information about the plugin.</description>
        <website>http://www.elgg.org/</website>
        <copyright>(C) Brett Profitt 2014</copyright>
        <license>GNU Public License version 2</license>

        <category>3rd_party_integration</category>

        <requires>
                <type>elgg_release</type>
                <version>1.9.1</version>
        </requires>

        <!-- The path is relative to the plugin's root. -->
        <screenshot>
                <description>Elgg profile.</description>
                <path>screenshots/profile.png</path>
        </screenshot>

        <provides>
                <type>plugin</type>
                <name>example_plugin</name>
                <version>1.5</version>
        </provides>

        <suggests>
                <type>plugin</type>
                <name>twitter</name>
                <version>1.0</version>
        </suggests>
</plugin_manifest>

Plugin coding guidelines¶

In addition to the Elgg Coding Standards, these are guidelines for creating plugins. Core plugins are being updated to this format and all plugin authors should follow these guidelines in their own plugins.

See also

Be sure to follow the Plugin skeleton for your plugin’s layout.

Warning

Don’t Modify Core

Contents

Use standardized routing with page handlers
Use standardized page handlers and scripts
The object/<subtype> view
Actions
Directly calling a file
Recommended

Use standardized routing with page handlers ¶

Example: Bookmarks plugin

Page handlers should accept the following standard URLs:

Purpose	URL
All	page_handler/all
User	page_handler/owner/<username>
User friends’	page_handler/friends/<username>
Single entity	page_handler/view/<guid>/<title>
Add	page_handler/add/<container_guid>
Edit	page_handler/edit/<guid>
Group list	page_handler/group/<guid>/owner

Include page handler scripts from the page handler. Almost every page handler should have a page handler script. (Example: bookmarks/all => mod/bookmarks/views/default/resources/bookmarks/all.php)
Pass arguments like entity guids to the resource view via $vars in elgg_view_resource().
Call elgg_gatekeeper() and elgg_admin_gatekeeper() in the page handler function if required.
The group URL should use views like resources/groups/*.php to render pages.
Page handlers should not contain HTML.
If upgrading a 1.7 plugin, update the URLs throughout the plugin. (Don’t forget to remove /pg/!)

Use standardized page handlers and scripts ¶

Example: Bookmarks plugin
Store page functionality in mod/<plugin>/views/default/resources/<page_handler>/<page_name>.php
Use elgg_view_resource('<page_handler>/<page_name>') to render that.
Use the content page layout in page handler scripts: $content = elgg_view_layout('content', $options);
Page handler scripts should not contain HTML
Call elgg_push_breadcrumb() in the page handler scripts.
No need to worry about setting the page owner if the URLs are in the standardized format
For group content, check the container_guid by using elgg_get_page_owner_entity()

The object/<subtype> view ¶

Example: Bookmarks plugin
Make sure there are views for $vars['full_view'] == true and $vars['full_view'] == false
Check for the object in $vars['entity'] . Use elgg_instance_of() to make sure it’s the type entity you want. Return true to short circuit the view if the entity is missing or wrong.
Use the new list body and list metadata views to help format. You should use almost no markup in these views.
Update action structure - Example: Bookmarks plugin.
Namespace action files and action names (example: mod/blog/actions/blog/save.php => action/blog/save)
Use the following action URLs:

Purpose URL

Add action/plugin/save

Edit action/plugin/save

Delete action/plugin/delete
Make the delete action accept action/<handler>/delete?guid=<guid> so the metadata entity menu has the correct URL by default
If updating a 1.7 plugin, replace calls to functions deprecated in 1.7 because these will produce visible errors on every load in 1.8

Actions ¶

Actions are transient states to perform an action such as updating the database or sending a notification to a user. Used correctly, actions provide a level of access control and prevent against CSRF attacks.

Actions require action (CSRF) tokens to be submitted via GET/POST, but these are added automatically by elgg_view_form() and by using the is_action argument of the output/url view.

Action best practices¶

Action files are included within Elgg’s action system; like views, they are not regular scripts executable by users. Do not boot the Elgg core in your file and direct users to load it directly.

Because actions are time-sensitive they are not suitable for links in emails or other delayed notifications. An example of this would be invitations to join a group. The clean way to create an invitation link is to create a page handler for invitations and email that link to the user. It is then the page handler’s responsibility to create the action links for a user to join or ignore the invitation request.

Consider that actions may be submitted via XHR requests, not just links or form submissions.

Directly calling a file ¶

This is an easy one: Don’t do it. With the exception of 3rd party application integration, there is not a reason to directly call a file in mods directory.

Recommended ¶

These points are good ideas, but are not yet in the official guidelines. Following these suggestions will help to keep your plugin consistent with Elgg core.

Update the widget views (see the blog or file widgets)
Update the group profile “widget” using blog or file plugins as example
Update the forms
- Move form bodies to /forms/<handler>/<action> to use Evan’s new elgg_view_form()
- Use input views in form bodies rather than html
- Add a function that prepares the form (see mod/file/lib/file.php for example)
- Integrate sticky forms (see the file plugin’s upload action and form prepare function)
Clean up CSS/HTML
- Should be able to remove almost all CSS (look for patterns that can be moved into core if you need CSS)
Use hyphens rather than underscores in classes/ids
Update the manifest.xml file to the 1.8 format. Use http://el.gg/manifest17to18 to automate this
Do not use the bundled category with your plugins. That is for plugins distributed with Elgg
Update functions deprecated in 1.8.
- Many registration functions simply added an elgg_ prefix for consistency
- See /engine/lib/deprecated-1.8.php for the full list. You can also set the debug level to warning to get visual reminders of deprecated functions
Don’t use register_shutdown_function as you may not have access to certain Elgg parts anymore (eg database). Instead use the shutdown system event

Accessibility¶

This page aims to list and document accessibility rules and best practices, to help core and plugins developpers to make Elgg the most accessible social engine framework that everyone dreams of.

Note

This is an ongoing work, please contribute on Github if you have some skills in this field!

Resources + references¶

Official WCAG Accessibility Guidelines Overview
Official WCAG Accessibility Guidelines
Resources for planning and implementing for accessibility
Practical tips from the W3C for improving accessibility
Preliminary review of websites for accessibility
Tools for checking the accessibility of websites
List of practical techniques for implementing accessibility (It would be great if someone could go through this and filter out all the ones that are relevant to Elgg)

Tips for implementing accessibility¶

All accessibility-related tickets reported to trac should be tagged with “a11y”, short for “accessibility”
Use core views such as output/*, and input/* to generate markup, since we can bake a11y concerns into these views
All images should have a descriptive alt attribute. Spacer or purely decorative graphics should have blank alt attributes
All <a> tags should have text or an accessible image inside. Otherwise screen readers will have to read the URL, which is a poor experience <a> tags should contain descriptive text, if possible, as opposed to generic text like “Click here”
Markup should be valid
Themes should not reset “outline” to nothing. :focus deserves a special visual treatment so that handicapped users can know where they are

Tips for testing accessibility¶

Use the tools linked to from the resources section. Example report for community.elgg.org on June 16, 2012
Try different font-size/zoom settings in your browser and make sure the theme remains usable
Turn off css to make sure the sequential order of the page makes sense

Documentation objectives and principles¶

Main accessibility rules
collect and document best practices
Provide code examples
Keep the document simple and usable
Make it usable for both beginner developpers and experts (from most common and easiest changes to elaborate techniques)

Ajax¶

The elgg/Ajax AMD module (introduced in Elgg 2.1) provides a set of methods for communicating with the server in a concise and uniform way, which allows plugins to collaborate on the request data, the server response, and the returned client-side data.

Client and server code written for the legacy API should not need modification.

Contents

Overview
Legacy elgg.ajax APIs

Overview ¶

All the ajax methods perform the following:

Client-side, the data option (if given as an object) is filtered by the hook ajax_request_data.
The request is made to the server, either rendering a view or a form, calling an action, or loading a path.
The method returns a jqXHR object, which can be used as a Promise.
Server-echoed content is turned into a response object (Elgg\Services\AjaxResponse) containing a string (or a JSON-parsed value).
The response object is filtered by the hook ajax_response.
The response object is used to create the HTTP response.
Client-side, the response data is filtered by the hook ajax_response_data.
The jqXHR promise is resolved and any success callbacks are called.

More notes:

All hooks have a type depending on the method and first argument. See below.
By default the elgg/spinner module is automatically used during requests.
User messages generated by system_message() and register_error() are collected and displayed on the client.
Elgg gives you a default error handler that shows a generic message if output fails.
PHP exceptions or denied resource return HTTP error codes, resulting in use of the client-side error handler.
The default HTTP method is POST for actions, otherwise GET. You can set it via options.method.
If a non-empty options.data is given, the default method is always POST.
For client caching, set options.method to "GET" and options.data.elgg_response_ttl to the max-age you want in seconds.
To save system messages for the next page load, set options.data.elgg_fetch_messages = 0. You may want to do this if you intent to redirect the user based on the response.
To stop client-side API from requiring AMD modules required server-side with elgg_require_js(), set options.data.elgg_fetch_deps = 0.
All methods accept a query string in the first argument. This is passed on to the fetch URL, but does not appear in the hook types.

Performing actions ¶

Consider this action:

// in myplugin/actions/do_math.php

elgg_ajax_gatekeeper();

$arg1 = (int)get_input('arg1');
$arg2 = (int)get_input('arg2');

// will be rendered client-side
system_message('We did it!');

echo json_encode([
    'sum' => $arg1 + $arg2,
    'product' => $arg1 * $arg2,
]);

To execute it, use ajax.action('<action_name>', options):

var Ajax = require('elgg/Ajax');
var ajax = new Ajax();

ajax.action('do_math', {
    data: {
        arg1: 1,
        arg2: 2
    },
}).done(function (output, statusText, jqXHR) {
    if (jqXHR.AjaxData.status == -1) {
        return;
    }

    alert(output.sum);
    alert(output.product);
});

Notes for actions:

All hooks have type action:<action_name>. So in this case, three hooks will be triggered:
- client-side "ajax_request_data", "action:do_math" to filter the request data (before it’s sent)
- server-side "ajax_response", "action:do_math" to filter the response (after the action runs)
- client-side "ajax_response_data", "action:do_math" to filter the response data (before the calling code receives it)
CSRF tokens are added to the request data.
The default method is POST.
An absolute action URL can be given in place of the action name.
Using forward() in an action simply sends the response. The URL given in not returned to the client.

Note

When setting data, use ajax.objectify($form) instead of $form.serialize(). Doing so allows the ajax_request_data plugin hook to fire and other plugins to alter/piggyback on the request.

Fetching data ¶

Consider this PHP script that runs at http://example.org/myplugin_time.

// in myplugin/start.php
elgg_register_page_handler('myplugin_time', 'myplugin_get_time');

function myplugin_get_time() {
    elgg_ajax_gatekeeper();

    echo json_encode([
        'rfc2822' => date(DATE_RFC2822),
        'day' => date('l'),
    ]);

    return true;
}

To fetch its output, use ajax.path('<url_path>', options).

var Ajax = require('elgg/Ajax');
var ajax = new Ajax();

ajax.path('myplugin_time').done(function (output, statusText, jqXHR) {
    if (jqXHR.AjaxData.status == -1) {
        return;
    }

    alert(output.rfc2822);
    alert(output.day);
});

Notes for paths:

The 3 hooks (see Actions above) will have type path:<url_path>. In this case, “path:myplugin_time”.
If the page handler echoes a regular web page, output will be a string containing the HTML.
An absolute URL can be given in place of the path name.

Fetching views ¶

Consider this view:

// in myplugin/views/default/myplugin/get_link.php

if (empty($vars['entity']) || !$vars['entity'] instanceof ElggObject) {
    return;
}

$object = $vars['entity'];
/* @var ElggObject $object */

echo elgg_view('output/url', [
    'text' => $object->getDisplayName(),
    'href' => $object->getUrl(),
    'is_trusted' => true,
]);

Since it’s a PHP file, we must register it for Ajax first:

// in myplugin_init()
elgg_register_ajax_view('myplugin/get_link');

To fetch the view, use ajax.view('<view_name>', options):

var Ajax = require('elgg/Ajax');
var ajax = new Ajax();

ajax.view('myplugin/get_link', {
    data: {
        guid: 123 // querystring
    },
}).done(function (output, statusText, jqXHR) {
    if (jqXHR.AjaxData.status == -1) {
        return;
    }

    $('.myplugin-link').html(output);
});

Notes for views:

The 3 hooks (see Actions above) will have type view:<view_name>. In this case, “view:myplugin/get_link”.
output will be a string with the rendered view.
The request data are injected into $vars in the view.
If the request data contains guid, the system sets $vars['entity'] to the corresponding entity or false if it can’t be loaded.

Warning

In ajax views and forms, note that $vars can be populated by client input. The data is filtered like get_input(), but may not be the type you’re expecting or may have unexpected keys.

Fetching forms ¶

Consider we have a form view. We register it for Ajax:

// in myplugin_init()
elgg_register_ajax_view('forms/myplugin/add');

To fetch this using ajax.form('<action_name>', options).

var Ajax = require('elgg/Ajax');
var ajax = new Ajax();

ajax.form('myplugin/add').done(function (output, statusText, jqXHR) {
    if (jqXHR.AjaxData.status == -1) {
        return;
    }

    $('.myplugin-form-container').html(output);
});

Notes for forms:

The 3 hooks (see Actions above) will have type form:<action_name>. In this case, “form:myplugin/add”.
output will be a string with the rendered view.
The request data are injected into $vars in your form view.
If the request data contains guid, the system sets $vars['entity'] to the corresponding entity or false if it can’t be loaded.

Note

Only the request data are passed to the requested form view (i.e. as a third parameter accepted by elgg_view_form()). If you need to pass attributes or parameters of the form element rendered by the input/form view (i.e. normally passed as a second parameter to elgg_view_form()), use the server-side hook view_vars, input/form.

Warning

In ajax views and forms, note that $vars can be populated by client input. The data is filtered like get_input(), but may not be the type you’re expecting or may have unexpected keys.

Piggybacking on an Ajax request ¶

The client-side ajax_request_data hook can be used to append or filter data being sent by an elgg/Ajax request.

Let’s say when the view foo is fetched, we want to also send the server some data:

// in your boot module
var Ajax = require('elgg/Ajax');
var elgg = require('elgg');

var ajax = new Ajax();

elgg.register_hook_handler(Ajax.REQUEST_DATA_HOOK, 'view:foo', function (name, type, params, data) {
    // send some data back
    data.bar = 1;
    return data;
});

This data can be read server-side via get_input('bar');.

Note

If data was given as a string (e.g. $form.serialize()), the request hooks are not triggered.

Piggybacking on an Ajax response ¶

The server-side ajax_response hook can be used to append or filter response data (or metadata).

Let’s say when the view foo is fetched, we want to also send the client some additional data:

use Elgg\Services\AjaxResponse;

function myplugin_append_ajax($hook, $type, AjaxResponse $response, $params) {

    // alter the value being returned
    $response->getData()->value .= " hello";

    // send some metadata back. Only client-side "ajax_response" hooks can see this!
    $response->getData()->myplugin_alert = 'Listen to me!';

    return $response;
}

// in myplugin_init()
elgg_register_plugin_hook_handler(AjaxResponse::RESPONSE_HOOK, 'view:foo', 'myplugin_append_ajax');

To capture the metadata send back to the client, we use the client-side ajax_response hook:

// in your boot module
var Ajax = require('elgg/Ajax');
var elgg = require('elgg');

elgg.register_hook_handler(Ajax.RESPONSE_DATA_HOOK, 'view:foo', function (name, type, params, data) {

    // the return value is data.value

    // the rest is metadata

    alert(data.myplugin_alert);

    return data;
});

Note

Only data.value is returned to the success function or available via the Deferred interface.

Note

Elgg uses these same hooks to deliver system messages over elgg/Ajax responses.

Handling errors ¶

Responses basically fall into three categories:

HTTP success (200) with status 0. No register_error() calls were made on the server.
HTTP success (200) with status -1. register_error() was called.
HTTP error (4xx/5xx). E.g. calling an action with stale tokens, or a server exception. In this case the done and success callbacks are not called.

You may need only worry about the 2nd case. We can do this by looking at jqXHR.AjaxData.status:

ajax.action('entity/delete?guid=123').done(function (value, statusText, jqXHR) {
    if (jqXHR.AjaxData.status == -1) {
        // a server error was already displayed
        return;
    }

    // remove element from the page
});

Requiring AMD modules ¶

Each response from an Ajax service will contain a list of AMD modules required server side with elgg_require_js(). When response data is unwrapped, these modules will be loaded asynchronously - plugins should not expect these modules to be loaded in their $.done() and $.then() handlers and must use require() for any modules they depend on. Additionally AMD modules should not expect the DOM to have been altered by an Ajax request when they are loaded - DOM events should be delegated and manipulations on DOM elements should be delayed until all Ajax requests have been resolved.

Legacy elgg.ajax APIs ¶

Elgg 1.8 introduced elgg.action, elgg.get, elgg.getJSON, and other methods which behave less consistently both client-side and server-side.

Legacy elgg.action ¶

Differences:

you must manually pull the output from the returned wrapper
the success handler will fire even if the action is prevented
the success handler will receive a wrapper object. You must look for wrapper.output
no ajax hooks

elgg.action('do_math', {
    data: {
        arg1: 1,
        arg2: 2
    },
    success: function (wrapper) {
        if (wrapper.output) {
            alert(wrapper.output.sum);
            alert(wrapper.output.product);
        } else {
            // the system prevented the action from running, but we really don't
            // know why
            elgg.ajax.handleAjaxError();
        }
    }
});

elgg.action notes¶

It’s best to echo a non-empty string, as this is easy to validate in the success function. If the action was not allowed to run for some reason, wrapper.output will be an empty string.

You may want to use the elgg/spinner module.

Elgg does not use wrapper.status for anything, but a call to register_error() causes it to be set to -1.

If the action echoes a non-JSON string, wrapper.output will contain that string.

elgg.action is based on jQuery.ajax and returns a jqXHR object (like a Promise), if you should want to use it.

After the PHP action completes, other plugins can alter the wrapper via the plugin hook 'output', 'ajax', which filters the wrapper as an array (not a JSON string).

A forward() call forces the action to be processed and output immediately, with the wrapper.forward_url value set to the normalized location given.

To make sure Ajax actions can only be executed via XHR, use elgg_ajax_gatekeeper().

elgg.action JSON response wrapper¶

{
    current_url: {String} "http://example.org/action/example/math", // not very useful
    forward_url: {String} "http://example.org/foo", ...if forward('foo') was called
    output: {String|Object} from echo in action
    status: {Number} 0 = success. -1 = an error was registered.
    system_messages: {Object}
}

Warning

It’s probably best to rely only on the output key, and validate it in case the PHP action could not run for some reason, e.g. the user was logged out or a CSRF attack did not provide tokens.

Warning

If forward() is used in response to a legacy ajax request (e.g. elgg.ajax), Elgg will always respond with this wrapper, even if not in an action.

Legacy view fetching ¶

A plugin can use a view script to handle XHR GET requests. Here’s a simple example of a view that returns a link to an object given by its GUID:

// in myplugin_init()
elgg_register_ajax_view('myplugin/get_link');

// in myplugin/views/default/myplugin/get_link.php

if (empty($vars['entity']) || !$vars['entity'] instanceof ElggObject) {
    return;
}

$object = $vars['entity'];
/* @var ElggObject $object */

echo elgg_view('output/url', [
    'text' => $object->getDisplayName(),
    'href' => $object->getUrl(),
    'is_trusted' => true,
]);

elgg.get('ajax/view/myplugin/get_link', {
    data: {
        guid: 123 // querystring
    },
    success: function (output) {
        $('.myplugin-link').html(output);
    }
});

The Ajax view system works significantly differently than the action system.

There are no access controls based on session status.

Non-XHR requests are automatically rejected.

GET vars are injected into $vars in the view.

If the request contains $_GET['guid'], the system sets $vars['entity'] to the corresponding entity or false if it can’t be loaded.

There’s no “wrapper” object placed around the view output.

System messages/errors shouldn’t be used, as they don’t display until the user loads another page.

Depending on the view’s suffix (.js, .html, .css, etc.), a corresponding Content-Type header is added.

Warning

In ajax views and forms, note that $vars can be populated by client input. The data is filtered like: get_input(), but may not be the type you’re expecting or may have unexpected keys.

Returning JSON from a view¶

If the view outputs encoded JSON, you must use elgg.getJSON to fetch it (or use some other method to set jQuery’s ajax option dataType to json). Your success function will be passed the decoded Object.

Here’s an example of fetching a view that returns a JSON-encoded array of times:

elgg.getJSON('ajax/view/myplugin/get_times', {
    success: function (data) {
        alert('The time is ' + data.friendly_time);
    }
});

Legacy form fetching ¶

If you register a form view (name starting with forms/), you can fetch it pre-rendered with elgg_view_form(). Simply use ajax/form/<action> (instead of ajax/view/<view_name>):

// in myplugin_init()
elgg_register_ajax_view('forms/myplugin/add');

elgg.get('ajax/form/myplugin/add', {
    success: function (output) {
        $('.myplugin-form-container').html(output);
    }
});

Only the request data are passed to the requested form view (i.e. as a third parameter accepted by elgg_view_form()). If you need to pass attributes or parameters of the form element rendered by the input/form view (i.e. normally passed as a second parameter to elgg_view_form()), use the server-side hook view_vars, input/form.

Warning

In ajax views and forms, note that $vars can be populated by client input. The data is filtered like: get_input(), but may not be the type you’re expecting or may have unexpected keys.

Legacy helper functions ¶

These functions extend jQuery’s native Ajax features.

elgg.get() is a wrapper for jQuery’s $.ajax(), but forces GET and does URL normalization.

// normalizes the url to the current <site_url>/activity
elgg.get('/activity', {
    success: function(resultText, success, xhr) {
        console.log(resultText);
    }
});

elgg.post() is a wrapper for jQuery’s $.ajax(), but forces POST and does URL normalization.

Authentication¶

Elgg provides everything needed to authenticate users via username/email and password out of the box, including:

remember-me cookies for persistent login

password reset logic

secure storage of passwords

logout

UIs for accomplishing all of the above

All that’s left for you to do as a developer is to use the built-in authentication functions to secure your pages and actions.

Working with the logged in user¶

Check whether the current user is logged in with elgg_is_logged_in():

if (elgg_is_logged_in()) {
  // do something just for logged-in users
}

Check if the current user is an admin with elgg_is_admin_logged_in():

if (elgg_is_admin_logged_in()) {
  // do something just for admins
}

Get the currently logged in user with elgg_get_logged_in_user_entity():

$user = elgg_get_logged_in_user_entity();

The returned object is an ElggUser so you can use all the methods and properties of that class to access information about the user. If the user is not logged in, this will return null, so be sure to check for that first.

Gatekeepers¶

Gatekeeper functions allow you to manage how code gets executed by applying access control rules.

Forward a user to the front page if they are not logged in with elgg_gatekeeper():

elgg_gatekeeper();

echo "Information for logged-in users only";

Note

In Elgg 1.8 and below this function was called gatekeeper()

Forward a user to the front page unless they are an admin with elgg_admin_gatekeeper():

elgg_admin_gatekeeper();

echo "Information for admins only";

Note

In Elgg 1.8 and below this function was called admin_gatekeeper()

Prevent CSRF attacks with action_gatekeeper().

action_gatekeeper();

// Mutate some state in the database on behalf of the logged in user...

This function should be used in Forms + Actions prior to Elgg 1.8.

Note

As of Elgg version 1.8 this function is called for all registered actions. There is no longer a need to call this function in your own actions. If you wish to protect other pages with action tokens then you can call this function.

Pluggable Authentication Modules¶

Elgg has support for pluggable authentication modules (PAM), which enables you to write your own authentication handlers. Whenever a request needs to get authenticated the system will call elgg_authenticate() which probes the registered PAM handlers until one returns success.

The preferred approach is to create a separate Elgg plugin which will have one simple task: to process an authentication request. This involves setting up an authentication handler in the plugin’s start.php file, and to register it with the PAM module so it will get processed whenever the system needs to authenticate a request.

The authentication handler is a function and takes a single parameter. Registering the handler is being done by register_pam_handler() which takes the name of the authentication handler, the importance and the policy as parameters. It is advised to register the handler in the plugin’s init function, for example:

function your_plugin_init() {
   // Register the authentication handler
   register_pam_handler('your_plugin_auth_handler');
}

function your_plugin_auth_handler($credentials) {
   // do things ...
}

// Add the plugin's init function to the system's init event
elgg_register_elgg_event_handler('init', 'system', 'your_plugin_init');

Importance¶

By default an authentication module is registered with an importance of sufficient.

In a list of authentication modules; if any one marked sufficient returns true, pam_authenticate() will also return true. The exception to this is when an authentication module is registered with an importance of required. All required modules must return true for pam_authenticate() to return true, regardless of whether all sufficient modules return true.

Passed credentials¶

The format of the credentials passed to the handler can vary, depending on the originating request. For example, a regular login via the login form will create a named array, with the keys username and password. If a request was made for example via XML-RPC then the credentials will be set in the HTTP header, so in this case nothing will get passed to the authentication handler and the handler will need to perform steps on its own to authenticate the request.

Return value¶

The authentication handle should return a boolean, indicating if the request could be authenticated or not. One caveat is that in case of a regular user login where credentials are available as username and password the user will get logged in. In case of the XML-RPC example the authentication handler will need to perform this step itself since the rest of the system will not have any idea of either possible formats of credentials passed nor its contents. Logging in a user is quite simple and is being done by login(), which expects an ElggUser object.

Context¶

Within the Elgg framework, context can be used to by your plugin’s functions to determine if they should run or not. You will be registering callbacks to be executed when particular events are triggered. Sometimes the events are generic and you only want to run your callback when your plugin caused the event to be triggered. In that case, you can use the page’s context.

You can explicitly set the context with set_context(). The context is a string and typically you set it to the name of your plugin. You can retrieve the context with the function get_context(). It’s however better to use elgg_push_context($string) to add a context to the stack. You can check if the context you want in in the current stack by calling elgg_in_context($context). Don’t forget to pop (with elgg_pop_context()) the context after you push one and don’t need it anymore.

If you don’t set it, Elgg tries to guess the context. If the page was called through the page handler, the context is set to the name of the handler which was set in elgg_register_page_handler(). If the page wasn’t called through the page handler, it uses the name of your plugin directory. If it cannot determine that, it returns main as the default context.

Sometimes a view will return different HTML depending on the context. A plugin can take advantage of that by setting the context before calling elgg_view() on the view and then setting the context back. This is frequently done with the search context.

Cron¶

If you setup cron correctly as described in Cron special hooks will be triggered so you can register for these hooks from your own code.

The example below registers a function for the daily cron.

function my_plugin_init() {
    elgg_register_plugin_hook_handler('cron', 'daily', 'my_plugin_cron_handler');
}

If timing is important in your cron hook be advised that the functions are executed in order of registration. This could mean that your function may start (a lot) later then you may have expected. However the parameters provided in the hook contain the original starting time of the cron, so you can always use that information.

function my_plugin_cron_handler($hook, $period, $return, $params) {
    $start_time = elgg_extract('time', $params);
}

See also

Events and Plugin Hooks has more information about hooks

Database¶

Persist user-generated content and settings with Elgg’s generic storage API.

Contents

Entities
Custom database functionality
- Example: Run SQL script on plugin activation
Systemlog
- System log storage
- Creating your own system log

Entities ¶

Creating an object ¶

To create an object in your code, you need to instantiate an ElggObject. Setting data is simply a matter of adding instance variables or properties. The built-in properties are:

``guid`` The entity’s GUID; set automatically
``owner_guid`` The owning user’s GUID
``site_guid`` The owning site’s GUID. This is set automatically when an instance of ElggObject gets created)
``subtype`` A single-word arbitrary string that defines what kind of object it is, for example blog
``access_id`` An integer representing the access level of the object
``title`` The title of the object
``description`` The description of the object

The object subtype is a special property. This is an arbitrary string that describes what the object is. For example, if you were writing a blog plugin, your subtype string might be blog. It’s a good idea to make this unique, so that other plugins don’t accidentally try and use the same subtype. For the purposes of this document, let’s assume we’re building a simple forum. Therefore, the subtype will be forum:

$object = new ElggObject();
$object->subtype = "forum";
$object->access_id = 2;
$object->save();

access_id is another important property. If you don’t set this, your object will be private, and only the creator user will be able to see it. Elgg defines constants for the special values of access_id:

ACCESS_PRIVATE Only the owner can see it
ACCESS_FRIENDS Only the owner and his/her friends can see it
ACCESS_LOGGED_IN Any logged in user can see it
ACCESS_PUBLIC Even visitors not logged in can see it

Saving the object will automatically populate the $object->guid property if successful. If you change any more base properties, you can call $object->save() again, and it will update the database for you.

You can set metadata on an object just like a standard property. Let’s say we want to set the SKU of a product:

$object->SKU = 62784;

If you assign an array, all the values will be set for that metadata. This is how, for example, you set tags.

Metadata cannot be persisted to the database until the entity has been saved, but for convenience, ElggEntity can cache it internally and save it when saving the entity.

Loading an object ¶

By GUID¶

$entity = get_entity($guid);
if (!$entity) {
    // The entity does not exist or you're not allowed to access it.
}

But what if you don’t know the GUID? There are several options.

By user, subtype or site¶

If you know the user ID you want to get objects for, or the subtype, or the site, you have several options. The easiest is probably to call the procedural function elgg_get_entities:

$entities = elgg_get_entities(array(
    'type' => $entity_type,
    'subtype' => $subtype,
    'owner_guid' => $owner_guid,
));

This will return an array of ElggEntity objects that you can iterate through. elgg_get_entities paginates by default, with a limit of 10; and offset 0.

You can leave out owner_guid to get all objects and leave out subtype or type to get objects of all types/subtypes.

If you already have an ElggUser – e.g. elgg_get_logged_in_user_entity, which always has the current user’s object when you’re logged in – you can simply use:

$objects = $user->getObjects($subtype, $limit, $offset)

But what about getting objects with a particular piece of metadata?

By metadata¶

The function elgg_get_entities_from_metadata allows fetching entities with metadata in a variety of ways.

By annotation¶

The function elgg_get_entities_from_annotations allows fetching entities with metadata in a variety of ways.

Note

As of Elgg 1.10 the default behaviour of elgg_get_entities_from_annotations was brought inline with the rest of the elgg_get_entities* functions.

Pre Elgg 1.10 the sorting of the entities was based on the latest addition of an annotation (in $options your could add $options[‘order_by’] = ‘maxtime ASC’ or $options[‘order_by’] = ‘maxtime DESC’. As of Elgg 1.10 this was changed to the creation time of the entity, just like the rest of the elgg_get_entities* functions. To get the old behaviour back add the following to your $options:

$options['selects'] = array('MAX(n_table.time_created) AS maxtime');
$options['group_by'] = 'n_table.entity_guid';
$options['order_by'] = 'maxtime ASC'

or

$options['order_by'] = 'maxtime DESC'

Displaying entities ¶

In order for entities to be displayed in listing functions you need to provide a view for the entity in the views system.

To display an entity, create a view EntityType/subtype where EntityType is one of the following:

object: for entities derived from ElggObject user: for entities derived from ElggUser site: for entities derived from ElggSite group: for entities derived from ElggGroup

A default view for all entities has already been created, this is called EntityType/default.

Entity Icons¶

Entity icons can be saved from uploaded files, existing local files, or existing ElggFile objects. These methods save all sizes of icons defined in the system.

$object = new ElggObject();
$object->title = 'Example entity';
$object->description = 'An example object with an icon.';

// from an uploaded file
$object->saveIconFromUploadedFile('file_upload_input');

// from a local file
$object->saveIconFromLocalFile('/var/data/generic_icon.png');

// from a saved ElggFile object
$file = get_entity(123);
if ($file instanceof ElggFile) {
        $object->saveIconFromElggFile($file);
}

$object->save();

The following sizes exist by default:

master - 550px at longer edge (not upscaled)
large - 200px at longer edge (not upscaled)
medium - 100px square
small - 40px square
tiny - 25px square
topbar - 16px square

Use elgg_get_icon_sizes() to get all possible icon sizes for a specific entity type and subtype. The function triggers the entity:icon:sizes hook.

To check if an icon is set, use $object->hasIcon($size).

You can retrieve the URL of the generated icon with``ElggEntity::getIconURL($params)`` method. This method accepts a $params argument as an array that specifies the size, type, and provide additional context for the hook to determine the icon to serve. The method triggers the entity:icon:url hook.

Use elgg_view_entity_icon($entity, $size, $vars) to render an icon. This will scan the following locations for a view and include the first match to .

views/$viewtype/icon/$type/$subtype.php
views/$viewtype/icon/$type/default.php
views/$viewtype/icon/default.php

Where

$viewtype: Type of view, e.g. 'default' or 'json'.
$type: Type of entity, e.g. 'group' or 'user'.
$subtype: Entity subtype, e.g. 'blog' or 'page'.

Icon methods support passing an icon type if an entity has more than one icon. For example, a user might have an avatar and a cover photo icon. You would pass 'cover_photo' as the icon type:

$object->saveIconFromUploadedFile('uploaded_photo', 'cover_photo');

$object->getIconUrl([
        'size' => 'medium',
        'type' => 'cover_photo'
]);

Note that custom icon types (e.g. cover photos) do not have preset sizes and coordinates. Use entity:<icon_type>:url hook to configure them.

By default icons will be stored in /icons/<icon_type>/<size>.jpg relative to entity’s directory on filestore. To provide an alternative location, use the entity:<icon_type>:file hook.

Adding, reading and deleting annotations ¶

Annotations could be used, for example, to track ratings. To annotate an entity you can use the object’s annotate() method. For example, to give a blog post a rating of 5, you could use:

$blog_post->annotate('rating', 5);

To retrieve the ratings on the blog post, use $blogpost->getAnnotations('rating') and if you want to delete an annotation, you can operate on the ElggAnnotation class, eg $annotation->delete().

Retrieving a single annotation can be done with get_annotation() if you have the annotation’s ID. If you delete an ElggEntity of any kind, all its metadata, annotations, and relationships will be automatically deleted as well.

Extending ElggEntity ¶

If you derive from one of the Elgg core classes, you’ll need to tell Elgg how to properly instantiate the new type of object so that get_entity() et al. will return the appropriate PHP class. For example, if I customize ElggGroup in a class called “Committee”, I need to make Elgg aware of the new mapping. Following is an example class extension:

// Class source
class Committee extends ElggGroup {

    protected function initializeAttributes() {
        parent::initializeAttributes();
        $this->attributes['subtype'] = 'committee';
    }

    // more customizations here
}

function committee_init() {

    register_entity_type('group', 'committee');

    // Tell Elgg that group subtype "committee" should be loaded using the Committee class
    // If you ever change the name of the class, use update_subtype() to change it
    add_subtype('group', 'committee', 'Committee');
}

register_elgg_event_handler('init', 'system', 'committee_init');

Now if you invoke get_entity() with the GUID of a committee object, you’ll get back an object of type Committee.

This template was extracted from the definition of ElggFile.

Advanced features ¶

Entity URLs¶

Entity urls are provided by the getURL() interface and provide the Elgg framework with a common way of directing users to the appropriate display handler for any given object.

For example, a profile page in the case of users.

The url is set using the elgg\_register\_entity\_url\_handler() function. The function you register must return the appropriate url for the given type - this itself can be an address set up by a page handler.

The default handler is to use the default export interface.

Entity loading performance¶

elgg_get_entities has a couple options that can sometimes be useful to improve performance.

preload_owners: If the entities fetched will be displayed in a list with the owner information, you can set this option to true to efficiently load the owner users of the fetched entities.
preload_containers: If the entities fetched will be displayed in a list using info from their containers, you can set this option to true to efficiently load them.
distinct: When Elgg fetches entities using an SQL query, Elgg must be sure that each entity row appears only once in the result set. By default it includes a DISTINCT modifier on the GUID column to enforce this, but some queries naturally return unique entities. Setting the distinct option to false will remove this modifier, and rely on the query to enforce its own uniqueness.

The internals of Elgg entity queries is a complex subject and it’s recommended to seek help on the Elgg Community site before using the distinct option.

Pre-1.8 Notes ¶

update_subtype(): This function is new in 1.8. In prior versions, you would need to edit the database by hand if you updated the class name associated with a given subtype.

elgg_register_entity_url_handler(): This function is new in 1.8. It deprecates register_entity_url_handler(), which you should use if developing for a pre-1.8 version of Elgg.

elgg_get_entities_from_metadata(): This function is new in 1.8. It deprecates get_entities_from_metadata(), which you should use if developing for a pre-1.8 version of Elgg.

Custom database functionality ¶

It is strongly recommended to use entities wherever possible. However, Elgg supports custom SQL queries using the database API.

Example: Run SQL script on plugin activation ¶

This example shows how you can populate your database on plugin activation.

my_plugin/activate.php:

if (!elgg_get_plugin_setting('database_version', 'my_plugin') {
    run_sql_script(__DIR__ . '/sql/activate.sql');
    elgg_set_plugin_setting('database_version', 1, 'my_plugin');
}

my_plugin/sql/activate.sql:

-- Create some table
CREATE TABLE prefix_custom_table(
    id INTEGER AUTO_INCREMENT,
    name VARCHAR(32),
    description VARCHAR(32),
    PRIMARY KEY (id)
);

-- Insert initial values for table
INSERT INTO prefix_custom_table (name, description)
VALUES ('Peter', 'Some guy'), ('Lisa', 'Some girl');

Note that Elgg execute statements through PHPs built-in functions and have limited support for comments. I.e. only single line comments are supported and must be prefixed by “– ” or “# “. A comment must start at the very beginning of a line.

Systemlog ¶

Note

This section need some attention and will contain outdated information

The default Elgg system log is a simple way of recording what happens within an Elgg system. It’s viewable and searchable directly from the administration panel.

System log storage ¶

A system log row is stored whenever an event concerning an object whose class implements the Loggable interface is triggered. ElggEntity and ElggExtender implement Loggable, so a system log row is created whenever an event is performed on all objects, users, groups, sites, metadata and annotations.

Common events include:

create
update
delete
login

Creating your own system log ¶

There are some reasons why you might want to create your own system log. For example, you might need to store a full copy of entities when they are updated or deleted, for auditing purposes. You might also need to notify an administrator when certain types of events occur.

To do this, you can create a function that listens to all events for all types of object:

register_elgg_event_handler('all','all','your_function_name');

Your function can then be defined as:

function your_function_name($object, $event) {
   if ($object instanceof Loggable) {
      ...
   }
}

You can then use the extra methods defined by Loggable to extract the information you need.

File System¶

Filestore¶

Location¶

Elgg’s filestore is located in the site’s dataroot that is configured during installation, and can be modified via site settings in Admin interface.

Directory Structure¶

The structure of the filestore is tied to file ownership by Elgg entities. Whenever the first file owned by an entity is written to the filestore, a directory corresponding to the entity GUID will be created within a parent bucket directory (buckets are bound to 5000 guids). E.g. files owned by user with guid 7777 will be located in 5000/7777/.

When files are created, filenames can contain subdirectory names (often referred to as $prefix throughout the code). For instance, avatars of the above user, can be found under 5000/7777/profile/.

File Objects¶

Writing Files¶

To write a file to the filestore, you would use an instance of ElggFile. Even though ElggFile extends ElggObject and can be stored as an actual Elgg entity, that is not always necessary (e.g. when writing thumbs of an image).

$file = new ElggFile();
$file->owner_guid = 7777;
$file->setFilename('portfolio/files/sample.txt');
$file->open('write');
$file->write('Contents of the file');
$file->close();

// to uprade this file to an entity
$file->subtype = 'file';
$file->save();

Reading Files¶

You can read file contents using instanceof of ElggFile.

// from an Elgg entity
$file = get_entity($file_guid);
readfile($file->getFilenameOnFilestore());

// arbitrary file on the filestore
$file = new ElggFile();
$file->owner_guid = 7777;
$file->setFilename('portfolio/files/sample.txt');

// option 1
$file->open('read');
$contents = $file->grabFile();
$file->close();

// option 2
$contents = file_get_contents($file->getFilenameOnFilestore());

Serving Files¶

You can serve files from filestore using elgg_get_inline_url() and elgg_get_download_url(). Both functions accept 3 arguments:

``file`` An instance of ElggFile to be served
``use_cookie`` If set to true, validity of the URL will be limited to current session
``expires`` Expiration time of the URL

You can use use_cookie and expires arguments as means of access control. For example, users avatars in most cases have a long expiration time and do not need to be restricted by current session - this will allows browsers to cache the images and file service will send appropriate Not Modified headers on consecutive requests.

For entities that are under Elgg’s access control, you may want to use cookies to ensure that access settings are respected and users do not share download URLs with somebody else.

You can also invalidated all previously generated URLs by updating file’s modified time, e.g. by using touch().

Embedding Files¶

Please note that due to their nature inline and download URLs are not suitable for embedding. Embed URLs must be permanent, whereas inline and download URLs are volatile (bound to user session and file modification time).

To embed an entity icon, use elgg_get_embed_url().

Handling File Uploads¶

In order to implement an action that saves a single file uploaded by a user, you can use the following approach:

// in your form
echo elgg_view('input/file', [
        'name' => 'upload',
        'label' => 'Select an image to upload',
        'help' => 'Only jpeg, gif and png images are supported',
]);

// in your action
$uploaded_files = elgg_get_uploaded_files('upload');
if (!$uploaded_files) {
        register_error("No file was uploaded");
        forward(REFERER);
}

$uploaded_file = array_shift($uploaded_files);
if (!$uploaded_file->isValid()) {
        $error = elgg_get_friendly_upload_error($uploaded_file->getError());
        register_error($error);
        forward(REFERER);
}

$supported_mimes = [
        'image/jpeg',
        'image/png',
        'image/gif',
];

$mime_type = ElggFile::detectMimeType($uploaded_file->getPathname(), $uploaded_file->getClientMimeType());
if (!in_array($mime_type, $supported_mimes)) {
        register_error("$mime_type is not supported");
        forward(REFERER);
}

$file = new ElggFile();
$file->owner_guid = elgg_get_logged_in_user_guid();
if ($file->acceptUploadedFile($uploaded_file)) {
        $file->save();
}

If your file input supports multiple files, you can iterate through them in your action:

// in your form
echo elgg_view('input/file', [
        'name' => 'upload[]',
        'multiple' => true,
        'label' => 'Select images to upload',
]);

// in your action
foreach (elgg_get_uploaded_files('upload') as $upload) {
        $file = new ElggFile();
        $file->owner_guid = elgg_get_logged_in_user_guid();
        if ($file->acceptUploadedFile($upload)) {
                $file->save();
        }
}

Forms + Actions¶

Create, update, or delete content.

Elgg forms submit to actions. Actions define the behavior for form submission.

This guide assumes basic familiarity with:

Contents

Registering actions
Actions available in core
- entity/delete
Forms
- Inputs
- Input types
Files and images
Sticky forms
Ajax
Security
Security Tokens
Signed URLs

Registering actions ¶

Actions must be registered before use. Use elgg_register_action for this:

elgg_register_action("example", __DIR__ . "/actions/example.php");

The mod/example/actions/example.php script will now be run whenever a form is submitted to http://localhost/elgg/action/example.

Warning

A stumbling point for many new developers is the URL for actions. The URL always uses /action/ (singular) and never /actions/ (plural). However, action script files are usually saved under the directory /actions/ (plural) and always have an extension.

Permissions ¶

By default, actions are only available to logged in users.

To make an action available to logged out users, pass "public" as the third parameter:

elgg_register_action("example", $filepath, "public");

To restrict an action to only administrators, pass "admin" for the last parameter:

elgg_register_action("example", $filepath, "admin");

Writing action files ¶

Use the get_input function to get access to request parameters:

$field = get_input('input_field_name', 'default_value');

You can then use the Database api to load entities and perform actions on them accordingly.

To indicate a successful action, use elgg_ok_response(). This function accepts data that you want to make available to the client for XHR calls (this data will be ignored for non-XHR calls)

$user = get_entity($guid);
// do something

$action_data = [
   'entity' => $user,
   'stats' => [
       'friends' => $user->getFriends(['count' => true]);
   ],
];

return elgg_ok_response($action_data, 'Action was successful', 'url/to/forward/to');

To indicate an error, use elgg_error_response()

$user = elgg_get_logged_in_user_entity();
if (!$user) {
   // show an error and forward the user to the referring page
   // send 404 error code on AJAX calls
   return elgg_error_response('User not found', REFERRER, ELGG_HTTP_NOT_FOUND);
}

if (!$user->canEdit()) {
   // show an error and forward to user's profile
   // send 403 error code on AJAX calls
   return elgg_error_response('You are not allowed to perform this action', $user->getURL(), ELGG_HTTP_FORBIDDEN);
}

Customizing actions ¶

Before executing any action, Elgg triggers a hook:

$result = elgg_trigger_plugin_hook('action', $action, null, true);

Where $action is the action being called. If the hook returns false then the action will not be executed.

Example: Captcha¶

The captcha module uses this to intercept the register and user/requestnewpassword actions and redirect them to a function which checks the captcha code. This check returns true if valid or false if not (which prevents the associated action from executing).

This is done as follows:

elgg_register_plugin_hook_handler("action", "register", "captcha_verify_action_hook");
elgg_register_plugin_hook_handler("action", "user/requestnewpassword", "captcha_verify_action_hook");

...

function captcha_verify_action_hook($hook, $entity_type, $returnvalue, $params) {
  $token = get_input('captcha_token');
  $input = get_input('captcha_input');

  if (($token) && (captcha_verify_captcha($input, $token))) {
    return true;
  }

  register_error(elgg_echo('captcha:captchafail'));

  return false;
}

This lets a plugin extend an existing action without the need to replace the whole action. In the case of the captcha plugin it allows the plugin to provide captcha support in a very loosely coupled way.

Actions available in core ¶

`entity/delete`¶

If your plugin does not implement any custom logic when deleting an entity, you can use bundled delete action

$guid = 123;
// You can provide optional forward path as a URL query parameter
$forward_url = 'path/to/forward/to';
echo elgg_view('output/url', array(
   'text' => elgg_echo('delete'),
   'href' => "action/entity/delete?guid=$guid&forward_url=$forward_url",
   'confirm' => true,
));

You can customize the success message keys for your entity type and subtype, using "entity:delete:$type:$subtype:success" and "entity:delete:$type:success" keys.

// to add a custom message when a blog post or file is deleted
// add the translations keys in your language files
return array(
   'entity:delete:object:blog:success' => 'Blog post has been deleted,
   'entity:delete:object:file:success' => 'File titled %s has been deleted',
);

Forms ¶

To output a form, use the elgg_view_form function like so:

echo elgg_view_form('example');

Doing this generates something like the following markup:

<form action="http://localhost/elgg/action/example">
  <fieldset>
    <input type="hidden" name="__elgg_ts" value="1234567890" />
    <input type="hidden" name="__elgg_token" value="3874acfc283d90e34" />
  </fieldset>
</form>

Elgg does some things automatically for you when you generate forms this way:

It sets the action to the appropriate URL based on the name of the action you pass to it

It adds some anti-csrf tokens (__elgg_ts and __elgg_token) to help keep your actions secure

It automatically looks for the body of the form in the forms/example view.

Put the content of your form in your plugin’s forms/example view:

// /mod/example/views/default/forms/example.php
echo elgg_view('input/text', array('name' => 'example'));

// defer form footer rendering
// this will allow other plugins to extend forms/example view
elgg_set_form_footer(elgg_view('input/submit'));

Now when you call elgg_view_form('example'), Elgg will produce:

<form action="http://localhost/elgg/action/example">
  <fieldset>
    <input type="hidden" name="__elgg_ts" value="...">
    <input type="hidden" name="__elgg_token" value="...">

    <input type="text" class="elgg-input-text" name="example">
    <div class="elgg-foot elgg-form-footer">
        <input type="submit" class="elgg-button elgg-button-submit" value="Submit">
    </div>
  </fieldset>
</form>

Inputs ¶

To render a form input, use one of the bundled input views, which cover all standard HTML input elements. See individual view files for a list of accepted parameters.

echo elgg_view('input/select', array(
   'required' => true,
   'name' => 'status',
   'options_values' => array(
      'draft' => elgg_echo('status:draft'),
      'published' => elgg_echo('status:published'),
   ),
   // most input views will render additional parameters passed to the view
   // as tag attributes
   'data-rel' => 'blog',
));

The above example will render a dropdown select input:

<select required="required" name="status" data-rel="blog" class="elgg-input-dropdown">
   <option value="draft">Draft</option>
   <option value="published">Published</option>
</select>

To ensure consistency in field markup, use elgg_view_field(), which accepts all the parameters of the input being rendered, as well as #label and #help parameters (both of which are optional and accept HTML or text).

echo elgg_view_field(array(
   '#type' => 'select',
   '#label' => elgg_echo('blog:status:label'),
   '#help' => elgg_view_icon('help') . elgg_echo('blog:status:help'),
   'required' => true,
   'name' => 'status',
   'options_values' => array(
      'draft' => elgg_echo('status:draft'),
      'published' => elgg_echo('status:published'),
   ),
   'data-rel' => 'blog',
));

The above will generate the following markup:

<div class="elgg-field elgg-field-required">
   <label for="elgg-field-1" class="elgg-field-label">Blog status<span title="Required" class="elgg-required-indicator">*</span></label>
   <select required="required" name="status" data-rel="blog" id="elgg-field-1" class="elgg-input-dropdown">
      <option value="draft">Draft</option>
      <option value="published">Published</option>
   </select>
   <div class="elgg-field-help elgg-text-help">
      <span class="elgg-icon-help elgg-icon"></span>This indicates whether or not the blog is visible in the feed
   </div>
</div>

Input types ¶

A list of bundled input types/views:

input/text - renders a text input <input type="text">
input/plaintext - renders a textarea <textarea></textarea>
input/longtext - renders a WYSIWYG text input
input/url - renders a url input <input type="url">
input/email - renders an email input <input type="email">
input/checkbox - renders a single checkbox <input type="checkbox">
input/checkboxes - renders a set of checkboxes with the same name
input/radio - renders one or more radio buttons <input type="radio">
input/submit - renders a submit button <input type="submit">
input/button - renders a button <button></button>
input/file - renders a file input <input type="file">
input/select - renders a select input <select></select>
input/hidden - renders a hidden input <input type="hidden">
input/password - renders a password input <input type="password">
input/number - renders a number input <input type="number">
input/date - renders a jQuery datepicker
input/access - renders an Elgg access level select
input/tags - renders an Elgg tags input
input/autocomplete - renders an Elgg entity autocomplete
input/captcha - placeholder view for plugins to extend
input/friendspicker - renders an Elgg friend picker
input/userpicker - renders an Elgg user autocomplete
input/location renders an Elgg location input

Files and images ¶

Use the input/file view in your form’s content view.

// /mod/example/views/default/forms/example.php
echo elgg_view(‘input/file’, array(‘name’ => ‘icon’));

Set the enctype of the form to multipart/form-data:

echo elgg_view_form(‘example’, array(
  ‘enctype’ => ‘multipart/form-data’
));

In your action file, use the $_FILES global to access the uploaded file:

$icon = $_FILES[‘icon’]

Sticky forms ¶

Sticky forms are forms that retain user input if saving fails. They are “sticky” because the user’s data “sticks” in the form after submitting, though it was never saved to the database. This greatly improves the user experience by minimizing data loss. Elgg 1.8 includes helper functions so you can make any form sticky.

Helper functions ¶

Sticky forms are implemented in Elgg 1.8 by the following functions:

elgg_make_sticky_form($name) Tells the engine to make all input on a form sticky.

elgg_clear_sticky_form($name) Tells the engine to discard all sticky input on a form.

elgg_is_sticky_form($name) Checks if $name is a valid sticky form.

elgg_get_sticky_values($name) Returns all sticky values saved for $name by elgg_make_sticky_form().

Overview ¶

The basic flow of using sticky forms is: Call elgg_make_sticky_form($name) at the top of actions for forms you want to be sticky. Use elgg_is_sticky_form($name) and elgg_get_sticky_values($name) to get sticky values when rendering a form view. Call elgg_clear_sticky_form($name) after the action has completed successfully or after data has been loaded by elgg_get_sticky_values($name).

Example: User registration ¶

Simple sticky forms require little logic to determine the input values for the form. This logic is placed at the top of the form body view itself.

The registration form view first sets default values for inputs, then checks if there are sticky values. If so, it loads the sticky values before clearing the sticky form:

// views/default/forms/register.php
$password = $password2 = '';
$username = get_input('u');
$email = get_input('e');
$name = get_input('n');

if (elgg_is_sticky_form('register')) {
     extract(elgg_get_sticky_values('register'));
     elgg_clear_sticky_form('register');
}

The registration action sets creates the sticky form and clears it once the action is completed:

// actions/register.php
elgg_make_sticky_form('register');

...

$guid = register_user($username, $password, $name, $email, false, $friend_guid, $invitecode);

if ($guid) {
     elgg_clear_sticky_form('register');
     ....
}

Example: Bookmarks ¶

The bundled plugin Bookmarks’ save form and action is an example of a complex sticky form.

The form view for the save bookmark action uses elgg_extract() to pull values from the $vars array:

// mod/bookmarks/views/default/forms/bookmarks/save.php
$title = elgg_extract('title', $vars, '');
$desc = elgg_extract('description', $vars, '');
$address = elgg_extract('address', $vars, '');
$tags = elgg_extract('tags', $vars, '');
$access_id = elgg_extract('access_id', $vars, ACCESS_DEFAULT);
$container_guid = elgg_extract('container_guid', $vars);
$guid = elgg_extract('guid', $vars, null);
$shares = elgg_extract('shares', $vars, array());

The page handler scripts prepares the form variables and calls elgg_view_form() passing the correct values:

// mod/bookmarks/pages/add.php
$vars = bookmarks_prepare_form_vars();
$content = elgg_view_form('bookmarks/save', array(), $vars);

Similarly, mod/bookmarks/pages/edit.php uses the same function, but passes the entity that is being edited as an argument:

$bookmark_guid = get_input('guid');
$bookmark = get_entity($bookmark_guid);

...

$vars = bookmarks_prepare_form_vars($bookmark);
$content = elgg_view_form('bookmarks/save', array(), $vars);

The library file defines bookmarks_prepare_form_vars(). This function accepts an ElggEntity as an argument and does 3 things:

Defines the input names and default values for form inputs.

Extracts the values from a bookmark object if it’s passed.

Extracts the values from a sticky form if it exists.

TODO: Include directly from lib/bookmarks.php

// mod/bookmarks/lib/bookmarks.php
function bookmarks_prepare_form_vars($bookmark = null) {
     // input names => defaults
  $values = array(
    'title' => get_input('title', ''), // bookmarklet support
    'address' => get_input('address', ''),
    'description' => '',
    'access_id' => ACCESS_DEFAULT,
    'tags' => '',
    'shares' => array(),
    'container_guid' => elgg_get_page_owner_guid(),
    'guid' => null,
    'entity' => $bookmark,
  );

  if ($bookmark) {
       foreach (array_keys($values) as $field) {
       if (isset($bookmark->$field)) {
         $values[$field] = $bookmark->$field;
       }
    }
  }

  if (elgg_is_sticky_form('bookmarks')) {
       $sticky_values = elgg_get_sticky_values('bookmarks');
       foreach ($sticky_values as $key => $value) {
      $values[$key] = $value;
    }
  }

  elgg_clear_sticky_form('bookmarks');

  return $values;
}

The save action checks the input, then clears the sticky form upon success:

// mod/bookmarks/actions/bookmarks/save.php
elgg_make_sticky_form('bookmarks');
...

if ($bookmark->save()) {
     elgg_clear_sticky_form('bookmarks');
}

Ajax ¶

See the Ajax guide for instructions on calling actions from JavaScript.

Security ¶

For enhanced security, all actions require an CSRF token. Calls to action URLs that do not include security tokens will be ignored and a warning will be generated.

A few views and functions automatically generate security tokens:

elgg_view('output/url', array('is_action' => TRUE));
elgg_view('input/securitytoken');
$url = elgg_add_action_tokens_to_url("http://localhost/elgg/action/example");

In rare cases, you may need to generate tokens manually:

$__elgg_ts = time();
$__elgg_token = generate_action_token($__elgg_ts);

You can also access the tokens from javascript:

elgg.security.token.__elgg_ts;
elgg.security.token.__elgg_token;

These are refreshed periodically so should always be up-to-date.

Security Tokens ¶

On occasion we need to pass data through an untrusted party or generate an “unguessable token” based on some data. The industry-standard HMAC algorithm is the right tool for this. It allows us to verify that received data were generated by our site, and were not tampered with. Note that even strong hash functions like SHA-2 should not be used without HMAC for these tasks.

Elgg provides elgg_build_hmac() to generate and validate HMAC message authentication codes that are unguessable without the site’s private key.

// generate a querystring such that $a and $b can't be altered
$a = 1234;
$b = "hello";
$query = http_build_query([
    'a' => $a,
    'b' => $b,
    'mac' => elgg_build_hmac([$a, $b])->getToken(),
]);
$url = "action/foo?$query";


// validate the querystring
$a = (int) get_input('a', '', false);
$b = (string) get_input('b', '', false);
$mac = get_input('mac', '', false);

if (elgg_build_hmac([$a, $b])->matchesToken($mac)) {
    // $a and $b have not been altered
}

Note: If you use a non-string as HMAC data, you must use types consistently. Consider the following:

$mac = elgg_build_hmac([123, 456])->getToken();

// type of first array element differs
elgg_build_hmac(["123", 456])->matchesToken($mac); // false

// types identical to original
elgg_build_hmac([123, 456])->matchesToken($mac); // true

Signed URLs ¶

Signed URLs offer a limited level of security for situations where action tokens are not suitable, for example when sending a confirmation link via email. URL signatures verify that the URL has been generated by your Elgg installation (using site secret) and that the URL query elements were not tampered with.

URLs a signed with an unguessable SHA-256 HMAC key. See Security Tokens for more details.

$url = elgg_http_add_url_query_element(elgg_normalize_url('confirm'), [
   'user_guid' => $user_guid,
]);

$url = elgg_http_get_signed_url($url);

notify_user($user_guid, $site->guid, 'Confirm', "Please confirm by clicking this link: $url");

Warning

Signed URLs do not offer CSRF protection and should not be used instead of action tokens.

Helper functions¶

Input and output¶

get_input($name) Grabs information from a form field (or any variable passed using GET or POST). Also sanitises input, stripping Javascript etc.
set_input($name, $value) Forces a value to a particular variable for subsequent retrieval by get_input()

Entity methods¶

$entity->getURL() Returns the URL of any entity in the system
$entity->getGUID() Returns the GUID of any entity in the system
$entity->canEdit() Returns whether or not the current user can edit the entity
$entity->getOwnerEntity() Returns the ElggUser owner of a particular entity

Entity and context retrieval¶

elgg_get_logged_in_user_entity() Returns the ElggUser for the current user
elgg_get_logged_in_user_guid() Returns the GUID of the current user
elgg_is_logged_in() Is the viewer logged in
elgg_is_admin_logged_in() Is the view an admin and logged in
elgg_gatekeeper() Shorthand for checking if a user is logged in. Forwards user to front page if not
elgg_admin_gatekeeper() Shorthand for checking the user is logged in and is an admin. Forwards user to front page if not
get_user($user_guid) Given a GUID, returns a full ElggUser entity
elgg_get_page_owner_guid() Returns the GUID of the current page owner, if there is one
elgg_get_page_owner_entity() Like elgg_get_page_owner_guid() but returns the full entity
elgg_get_context() Returns the current page’s context - eg “blog” for the blog plugin, “thewire” for the wire, etc. Returns “main” as default
elgg_set_context($context) Forces the context to be a particular value
elgg_push_context($context) Adds a context to the stack
elgg_pop_context() Removes the top context from the stack
elgg_in_context($context) Checks if you’re in a context (this checks the complete stack, eg. ‘widget’ in ‘groups’)

Plugins¶

elgg_is_active_plugin($plugin_id) Check if a plugin is installed and enabled

Interface and annotations¶

elgg_view_image_block($icon, $info) Return the result in a formatted list
elgg_view_comments($entity) Returns any comments associated with the given entity
elgg_get_friendly_time($unix_timestamp) Returns a date formatted in a friendlier way - “18 minutes ago”, “2 days ago”, etc.
You can pass 'use_hover' => false to the user icon view if you don’t want the avatar drop down menu to appear e.g.

elgg_view_entity_icon($user, 'small', array('use_hover' => false));

Internationalization¶

Make your UI translatable into many different languages.

If you’d like to contribute translations to Elgg, see the contributors’ guide.

The default language is en for English. Currently Elgg will always fall back to an English translation, even if the site’s language is not English; this is a known bug.

Overview¶

Translations are stored in PHP files in the /languages directory of your plugin. Each file corresponds to a language. The format is /languages/{language-code}.php where {language-code} is the ISO 639-1 short code for the language. For example:

<?php // mod/example/languages/en.php

return [
        'example:text' => 'Some example text',
];

To override an existing translation, include it in your plugin’s language file, and make sure your plugin is ordered later on the Admin > Plugins page:

<?php // mod/better_example/languages/en.php

return [
        'example:text' => 'Some better text!',
];

Note

Unless you are overriding core’s or another plugin’s language strings, it is good practice for the language keys to start with your plugin name. For example: yourplugin:success, yourplugin:title, etc. This helps avoid conflicts with other language keys.

Server-side API¶

elgg_echo($key, $args, $language)

Output the translation of the key in the current language.

Example:

echo elgg_echo('example:text');

It also supports variable replacement using sprintf syntax:

// 'welcome' => 'Welcome to %s, %s!'
echo elgg_echo('welcome', [
        elgg_get_config('sitename'),
        elgg_get_logged_in_user_entity()->name,
]);

To force which language should be used for translation, set the third parameter:

echo elgg_echo('welcome', [], $user->language);

To first test whether elgg_echo() can find a translation:

$key = 'key:that:might:not:exist';
if (!elgg_language_key_exists($key)) {
        $key = 'fallback:key';
}

echo elgg_echo($key);

Note

Some APIs allow creating translations for new keys. Translators should always include an English translation as a fallback. This makes elgg_language_key_exists($key) a reliable way to predict whether elgg_echo($key) will succeed.

Javascript API¶

elgg.echo(key, args)

This function is like elgg_echo in PHP.

Client-side translations are loaded asynchronously. Ensure translations are available by requiring the “elgg” AMD module:

define(function(require) {
        var elgg = require("elgg");

        alert(elgg.echo('my_key'));
});

Translations are also available after the init, system JavaScript event.

JavaScript¶

Contents

AMD ¶

Developers should use the AMD (Asynchronous Module Definition) standard for writing JavaScript code in Elgg.

Here we’ll describe making and executing AMD modules. The RequireJS documentation for defining modules may also be of use.

Executing a module in the current page ¶

Telling Elgg to load an existing module in the current page is easy:

<?php
elgg_require_js("myplugin/say_hello");

On the client-side, this will asynchronously load the module, load any dependencies, and execute the module’s definition function, if it has one.

Defining the Module ¶

Here we define a basic module that alters the page, by passing a “definition function” to define():

// in views/default/myplugin/say_hello.js

define(function(require) {
    var elgg = require("elgg");
    var $ = require("jquery");

    $('body').append(elgg.echo('hello_world'));
});

The module’s name is determined by the view name, which here is myplugin/say_hello.js. We strip the .js extension, leaving myplugin/say_hello.

Warning

The definition function must have one argument named require.

Making modules dependent on other modules ¶

Below we refactor a bit so that the module depends on a new myplugin/hello module to provide the greeting:

// in views/default/myplugin/hello.js

define(function(require) {
    var elgg = require("elgg");

    return elgg.echo('hello_world');
});

// in views/default/myplugin/say_hello.js

define(function(require) {
    var $ = require("jquery");
    var hello = require("myplugin/hello");

    $('body').append(hello);
});

Passing settings to modules ¶

The `elgg.data` plugin hooks¶

The elgg module provides an object elgg.data which is populated from two server side hooks:

elgg.data, site: This filters an associative array of site-specific data passed to the client and cached.
elgg.data, page: This filters an associative array of uncached, page-specific data passed to the client.

Let’s pass some data to a module:

<?php

function myplugin_config_site($hook, $type, $value, $params) {
    // this will be cached client-side
    $value['myplugin']['api'] = elgg_get_site_url() . 'myplugin-api';
    $value['myplugin']['key'] = 'none';
    return $value;
}

function myplugin_config_page($hook, $type, $value, $params) {
    $user = elgg_get_logged_in_user_entity();
    if ($user) {
        $value['myplugin']['key'] = $user->myplugin_api_key;
        return $value;
    }
}

elgg_register_plugin_hook_handler('elgg.data', 'site', 'myplugin_config_site');
elgg_register_plugin_hook_handler('elgg.data', 'page', 'myplugin_config_page');

define(function(require) {
    var elgg = require("elgg");

    var api = elgg.data.myplugin.api;
    var key = elgg.data.myplugin.key; // "none" or a user's key

    // ...
});

Note

In elgg.data, page data overrides site data. Also note json_encode() is used to copy data client-side, so the data must be JSON-encodable.

Making a config module¶

You can use a PHP-based module to pass values from the server. To make the module myplugin/settings, create the view file views/default/myplugin/settings.js.php (note the double extension .js.php).

<?php

// this will be cached client-side
$settings = [
    'api' => elgg_get_site_url() . 'myplugin-api',
    'key' => null,
];
?>
define(<?php echo json_encode($settings); ?>);

You must also manually register the view as an external resource:

<?php
// note the view name does not include ".php"
elgg_register_simplecache_view('myplugin/settings.js');

Note

The PHP view is cached, so you should treat the output as static (the same for all users) and avoid session-specific logic.

Setting the URL of a module ¶

You may have an AMD script outside your views you wish to make available as a module.

The best way to accomplish this is by configuring the path to the file using the views.php file in the root of your plugin:

<?php // views.php
return [
    'default' => [
        'underscore.js' => 'vendor/bower-asset/underscore/underscore.min.js',
    ],
];

If you’ve copied the script directly into your plugin instead of managing it with Composer, you can use something like this instead:

<?php // views.php
return [
    'default' => [
        'underscore.js' => __DIR__ . '/bower_components/underscore/underscore.min.js',
    ],
];

That’s it! Elgg will now load this file whenever the “underscore” module is requested.

Using traditional JS libraries as modules ¶

It’s possible to support JavaScript libraries that do not declare themselves as AMD modules (i.e. they declare global variables instead) if you shim them by setting exports and deps in elgg_define_js:

// set the path, define its dependencies, and what value it returns
elgg_define_js('jquery.form', [
    'deps' => ['jquery'],
    'exports' => 'jQuery.fn.ajaxForm',
]);

When this is requested client-side:

The jQuery module is loaded, as it’s marked as a dependency.
https://elgg.example.org/cache/125235034/views/default/jquery.form.js is loaded and executed.
The value of window.jQuery.fn.ajaxForm is returned by the module.

Warning

Calls to elgg_define_js() must be in an init, system event handler.

Some things to note¶

Do not use elgg.provide() anymore nor other means to attach code to elgg or other global objects. Use modules.
Return the value of the module instead of adding to a global variable.
Static (.js,.css,etc.) files are automatically minified and cached by Elgg’s simplecache system.
The configuration is also cached in simplecache, and should not rely on user-specific values like get_language().

Booting your plugin ¶

To add functionality to each page, or make sure your hook handlers are registered early enough, you may create a boot module for your plugin, with the name boot/<plugin_id>.

// in views/default/boot/example.js

define(function(require) {
    var elgg = require("elgg");
    var Plugin = require("elgg/Plugin");

    // plugin logic
    function my_init() { ... }

    return new Plugin({
        // executed in order of plugin priority
        init: function () {
            elgg.register_hook_handler("init", "system", my_init, 400);
        }
    });
});

When your plugin is active, this module will automatically be loaded on each page. Other modules can depend on elgg/init to make sure all boot modules are loaded.

Each boot module must return an instance of elgg/Plugin. The constructor must receive an object with a function in the init key. The init function will be called in the order of the plugin in Elgg’s admin area.

Note

Though not strictly necessary, you may want to use the init, system event to control when your initialization code runs with respect to other modules.

Warning

A boot module cannot depend on the modules elgg/init or elgg/ready.

Modules provided with Elgg ¶

Modules `jquery` and `jquery-ui`¶

You must depend on these modules to use $ or $.ui methods. In the future Elgg may stop loading these by default.

Module `elgg`¶

elgg.echo()

Translate interface text

elgg.echo('example:text', ['arg1']);

elgg.system_message()

Display a status message to the user.

elgg.system_message(elgg.echo('success'));

elgg.register_error()

Display an error message to the user.

elgg.register_error(elgg.echo('error'));

elgg.normalize_url()

Normalize a URL relative to the elgg root:

// "http://localhost/elgg/blog"
elgg.normalize_url('/blog');

elgg.forward()

Redirect to a new page.

elgg.forward('/blog');

This function automatically normalizes the URL.

elgg.parse_url()

Parse a URL into its component parts:

// returns {
//   fragment: "fragment",
//   host: "community.elgg.org",
//   path: "/file.php",
//   query: "arg=val"
// }
elgg.parse_url('http://community.elgg.org/file.php?arg=val#fragment');

elgg.get_page_owner_guid()

Get the GUID of the current page’s owner.

elgg.register_hook_handler()

Register a hook handler with the event system. For best results, do this in a plugin boot module.

// boot module: /views/default/boot/example.js
define(function (require) {
    var elgg = require('elgg');
    var Plugin = require('elgg/Plugin');

    elgg.register_hook_handler('foo', 'bar', function () { ... });

    return new Plugin();
});

elgg.trigger_hook()

Emit a hook event in the event system. For best results depend on the elgg/init module.

// old
value = elgg.trigger_hook('my_plugin:filter', 'value', {}, value);

define(function (require) {
    require('elgg/init');
    var elgg = require('elgg');

    value = elgg.trigger_hook('my_plugin:filter', 'value', {}, value);
});

elgg.security.refreshToken()

Force a refresh of all XSRF tokens on the page.

This is automatically called every 5 minutes by default.

This requires a valid security token in 1.8, but not in 1.9.

The user will be warned if their session has expired.

elgg.security.addToken()

Add a security token to an object, URL, or query string:

// returns {
//   __elgg_token: "1468dc44c5b437f34423e2d55acfdd87",
//   __elgg_ts: 1328143779,
//   other: "data"
// }
elgg.security.addToken({'other': 'data'});

// returns: "action/add?__elgg_ts=1328144079&__elgg_token=55fd9c2d7f5075d11e722358afd5fde2"
elgg.security.addToken("action/add");

// returns "?arg=val&__elgg_ts=1328144079&__elgg_token=55fd9c2d7f5075d11e722358afd5fde2"
elgg.security.addToken("?arg=val");

elgg.get_logged_in_user_entity()

Returns the logged in user as an JS ElggUser object.

elgg.get_logged_in_user_guid()

Returns the logged in user’s guid.

elgg.is_logged_in()

True if the user is logged in.

elgg.is_admin_logged_in()

True if the user is logged in and is an admin.

elgg.config.get_language()

Get the current page’s language.

There are a number of configuration values set in the elgg object:

// The root of the website.
elgg.config.wwwroot;
// The default site language.
elgg.config.language;
// The current page's viewtype
elgg.config.viewtype;
// The Elgg version (YYYYMMDDXX).
elgg.config.version;
// The Elgg release (X.Y.Z).
elgg.config.release;

Module `elgg/Ajax`¶

See the Ajax page for details.

Module `elgg/init`¶

elgg/init loads and initializes all boot modules in priority order and triggers the [init, system] hook.

Require this module to make sure all plugins are ready.

Module `elgg/Plugin`¶

Used to create a boot module.

Module `elgg/ready`¶

elgg/ready loads and initializes all plugin boot modules in priority order.

Require this module to make sure all plugins are ready.

Module `elgg/spinner`¶

The elgg/spinner module can be used to create an Ajax loading indicator fixed to the top of the window.

define(function (require) {
   var spinner = require('elgg/spinner');

   elgg.action('friend/add', {
       beforeSend: spinner.start,
       complete: spinner.stop,
       success: function (json) {
           // ...
       }
   });
});

Note

The elgg/Ajax module uses the spinner by default.

Module `elgg/popup`¶

The elgg/popup module can be used to display an overlay positioned relatively to its anchor (trigger).

The elgg/popup module is loaded by default, and binding a popup module to an anchor is as simple as adding rel="popup" attribute and defining target module with a href (or data-href) attribute. Popup module positioning can be defined with data-position attribute of the trigger element.

echo elgg_format_element('div', [
   'class' => 'elgg-module-popup hidden',
   'id' => 'popup-module',
], 'Popup module content');

// Simple anchor
echo elgg_view('output/url', [
   'href' => '#popup-module',
   'text' => 'Show popup',
   'rel' => 'popup',
]);

// Button with custom positioning of the popup
echo elgg_format_element('button', [
   'rel' => 'popup',
   'class' => 'elgg-button elgg-button-submit',
   'text' => 'Show popup',
   'data-href' => '#popup-module',
   'data-position' => json_encode([
      'my' => 'center bottom',
      'at' => 'center top',
   ]),
]);

The elgg/popup module allows you to build out more complex UI/UX elements. You can open and close popup modules programmatically:

define(function(require) {
   var $ = require('jquery');
   $(document).on('click', '.elgg-button-popup', function(e) {

      e.preventDefault();

      var $trigger = $(this);
      var $target = $('#my-target');
              var $close = $target.find('.close');

      require(['elgg/popup'], function(popup) {
                popup.open($trigger, $target, {
                       'collision': 'fit none'
                });

        $close.on('click', popup.close);
              });
   });
});

You can use getOptions, ui.popup plugin hook to manipulate the position of the popup before it has been opened. You can use jQuery open and close events to manipulate popup module after it has been opened or closed.

define(function(require) {

   var elgg = require('elgg');
   var $ = require('jquery');

   $('#my-target').on('open', function() {
      var $module = $(this);
      var $trigger = $module.data('trigger');

      elgg.ajax('ajax/view/my_module', {
         beforeSend: function() {
            $trigger.hide();
            $module.html('').addClass('elgg-ajax-loader');
         },
         success: function(output) {
            $module.removeClass('elgg-ajax-loader').html(output);
         }
      });
   }).on('close', function() {
      var $trigger = $(this).data('trigger');
      $trigger.show();
   });
});

Open popup modules will always contain the following data that can be accessed via $.data():

trigger - jQuery element used to trigger the popup module to open

position - An object defining popup module position that was passed to $.position()

By default, target element will be appended to $('body') thus altering DOM hierarchy. If you need to preserve the DOM position of the popup module, you can add .elgg-popup-inline class to your trigger.

Module `elgg/widgets`¶

Plugins that load a widget layout via Ajax should initialize via this module:

require(['elgg/widgets'], function (widgets) {
    widgets.init();
});

Module `elgg/ckeditor`¶

This module can be used to add WYSIWYG editor to a textarea (requires ckeditor plugin to be enabled). Note that WYSIWYG will be automatically attached to all instances of .elgg-input-longtext.

require(['elgg/ckeditor'], function (elggCKEditor) {
   elggCKEditor.bind('#my-text-area');

   // Toggle CKEditor
   elggCKEditor.toggle('#my-text-area');

   // Focus on CKEditor input
   elggCKEditor.focus('#my-text-area');
   // or
   $('#my-text-area').trigger('focus');

   // Reset CKEditor input
   elggCKEditor.reset('#my-text-area');
   // or
   $('#my-text-area').trigger('reset');

});

Inline tabs component ¶

Inline tabs component fires an open event whenever a tabs is open and, in case of ajax tabs, finished loading:

// Add custom animation to tab content
    require(['jquery', 'elgg/ready'], function($) {
            $(document).on('open', '.theme-sandbox-tab-callback', function() {
                    $(this).find('a').text('Clicked!');
                    $(this).data('target').hide().show('slide', {
                            duration: 2000,
                            direction: 'right',
                            complete: function() {
                                    alert('Thank you for clicking. We hope you enjoyed the show!');
                                    $(this).css('display', ''); // .show() adds display property
                            }
                    });
            });
    });

Traditional scripts ¶

Although we highly recommend using AMD modules, you can register scripts with elgg_register_js:

elgg_register_js('jquery', $cdnjs_url);

This will override any URLs previously registered under this name.

Load a library on the current page with elgg_load_js:

elgg_load_js('jquery');

This will load the library in the page footer. You must use the require() function to depend on modules like elgg and jquery.

Warning

Using inline scripts is NOT SUPPORTED because:

They are not testable (maintainability)
They are not cacheable (performance)
They prevent use of Content-Security-Policy (security)
They prevent scripts from being loaded with defer or async (performance)

Inline scripts in core or bundled plugins are considered legacy bugs.

Hooks ¶

The JS engine has a hooks system similar to the PHP engine’s plugin hooks: hooks are triggered and plugins can register functions to react or alter information. There is no concept of Elgg events in the JS engine; everything in the JS engine is implemented as a hook.

Registering hook handlers ¶

Handler functions are registered using elgg.register_hook_handler(). Multiple handlers can be registered for the same hook.

The following example registers the handleFoo function for the foo, bar hook.

define(function (require) {
    var elgg = require('elgg');
    var Plugin = require('elgg/Plugin');

    function handleFoo(hook, type, params, value) {
        // do something
    }

    elgg.register_hook_handler('foo', 'bar', handleFoo);

    return new Plugin();
});

The handler function ¶

The handler will receive 4 arguments:

hook - The hook name
type - The hook type
params - An object or set of parameters specific to the hook
value - The current value

The value will be passed through each hook. Depending on the hook, callbacks can simply react or alter data.

Triggering custom hooks ¶

Plugins can trigger their own hooks:

define(function(require) {
    require('elgg/init');
    var elgg = require('elgg');

    elgg.trigger_hook('name', 'type', {params}, "value");
});

Note

Be aware of timing. If you don’t depend on elgg/init, other plugins may not have had a chance to register their handlers.

Available hooks ¶

init, system: Plugins should register their init functions for this hook. It is fired after Elgg’s JS is loaded and all plugin boot modules have been initialized. Depend on the elgg/init module to be sure this has completed.
ready, system: This hook is fired when the system has fully booted (after init). Depend on the elgg/ready module to be sure this has completed.
getOptions, ui.popup: This hook is fired for pop up displays ("rel"="popup") and allows for customized placement options.
getOptions, ui.lightbox: This hook can be used to filter options passed to $.colorbox()
config, ckeditor: This filters the CKEditor config object. Register for this hook in a plugin boot module. The defaults can be seen in the module elgg/ckeditor/config.
prepare, ckeditor: This hook can be used to decorate CKEDITOR global. You can use this hook to register new CKEditor plugins and add event bindings.
ajax_request_data, *: This filters request data sent by the elgg/Ajax module. See Ajax for details.
ajax_response_data, *: This filters the response data returned to users of the elgg/Ajax module. See Ajax for details.
insert, editor: This hook is triggered by the embed plugin and can be used to filter content before it is inserted into the textarea. This hook can also be used by WYSIWYG editors to insert content using their own API (in this case the handler should return false). See ckeditor plugin for an example.

Third-party assets ¶

We recommend managing third-party scripts and styles with Composer. Elgg core uses fxp/composer-asset-plugin for this purpose. This plugin allows you to pull dependencies from the Bower or NPM package repositories, but using the Composer command-line tool.

For example, to include jQuery, you could run the following Composer commands:

composer global require fxp/composer-asset-plugin:~1.1.4
composer require bower-asset/jquery:~2.0

Note

fxp/composer-asset-plugin must be installed globally! See https://github.com/francoispluchino/composer-asset-plugin for more info.

Menus¶

Elgg contains helper code to build menus throughout the site.

Every single menu requires a name, as does every single menu item. These are required in order to allow easy overriding and manipulation, as well as to provide hooks for theming.

Contents

Basic usage
Advanced usage
Creating a new menu
Theming
JavaScript

Basic usage ¶

Basic functionalities can be achieved through these two functions:

elgg_register_menu_item() to add an item to a menu

elgg_unregister_menu_item() to remove an item from a menu

You normally want to call them from your plugin’s init function.

Examples¶

// Add a new menu item to the site main menu
elgg_register_menu_item('site', array(
        'name' => 'itemname',
        'text' => 'This is text of the item',
        'href' => '/item/url',
));

// Remove the "Elgg" logo from the topbar menu
elgg_unregister_menu_item('topbar', 'elgg_logo');

Advanced usage ¶

You can get more control over menus by using plugin hooks and the public methods provided by the ElggMenuItem class.

There are two hooks that can be used to modify a menu:

'register', 'menu:<menu name>' to add or modify items (especially in dynamic menus)
'prepare', 'menu:<menu name>' to modify the structure of the menu before it is displayed

When you register a plugin hook handler, replace the <menu name> part with the internal name of the menu.

The third parameter passed into a menu handler contains all the menu items that have been registered so far by Elgg core and other enabled plugins. In the handler we can loop through the menu items and use the class methods to interact with the properties of the menu item.

Examples¶

Example 1: Change the URL for menu item called “albums” in the owner_block menu:

/**
 * Initialize the plugin
 */
function my_plugin_init() {
        // Register a plugin hook handler for the owner_block menu
        elgg_register_plugin_hook_handler('register', 'menu:owner_block', 'my_owner_block_menu_handler');
}

/**
 * Change the URL of the "Albums" menu item in the owner_block menu
 */
function my_owner_block_menu_handler($hook, $type, $items, $params) {
        $owner = $params['entity'];

        // Owner can be either user or a group, so we
        // need to take both URLs into consideration:
        switch ($owner->getType()) {
                case 'user':
                        $url = "album/owner/{$owner->guid}";
                        break;
                case 'group':
                        $url = "album/group/{$owner->guid}";
                        break;
        }

        foreach ($items as $key => $item) {
                if ($item->getName() == 'albums') {
                        // Set the new URL
                        $item->setURL($url);
                        break;
                }
        }

        return $items;
}

Example 2: Modify the entity menu for the ElggBlog objects

Remove the thumb icon
Change the “Edit” text into a custom icon

/**
 * Initialize the plugin
 */
function my_plugin_init() {
        // Register a plugin hook handler for the entity menu
        elgg_register_plugin_hook_handler('register', 'menu:entity', 'my_entity_menu_handler');
}

/**
 * Customize the entity menu for ElggBlog objects
 */
function my_entity_menu_handler($hook, $type, $items, $params) {
        // The entity can be found from the $params parameter
        $entity = $params['entity'];

        // We want to modify only the ElggBlog objects, so we
        // return immediately if the entity is something else
        if (!$entity instanceof ElggBlog) {
                return $menu;
        }

        foreach ($items as $key => $item) {
                switch ($item->getName()) {
                        case 'likes':
                                // Remove the "likes" menu item
                                unset($items[$key]);
                                break;
                        case 'edit':
                                // Change the "Edit" text into a custom icon
                                $item->setText(elgg_view_icon('pencil'));
                                break;
                }
        }

        return $items;
}

Creating a new menu ¶

Elgg provides multiple different menus by default. Sometimes you may however need some menu items that don’t fit in any of the existing menus. If this is the case, you can create your very own menu with the elgg_view_menu() function. You must call the function from the view, where you want to menu to be displayed.

Example: Display a menu called “my_menu” that displays it’s menu items in alphapetical order:

// in a resource view
echo elgg_view_menu('my_menu', array('sort_by' => 'title'));

You can now add new items to the menu like this:

// in plugin init
elgg_register_menu_item('my_menu', array(
        'name' => 'my_page',
        'href' => 'path/to/my_page',
        'text' => elgg_echo('my_plugin:my_page'),
));

Furthermore it is now possible to modify the menu using the hooks 'register', 'menu:my_menu' and 'prepare', 'menu:my_menu'.

Theming ¶

The menu name, section names, and item names are all embedded into the HTML as CSS classes (normalized to contain only hyphens, rather that underscores or colons). This increases the size of the markup slightly but provides themers with a high degree of control and flexibility when styling the site.

Example: The following would be the output of the foo menu with sections alt and default containing items baz and bar respectively.

<ul class="elgg-menu elgg-menu-foo elgg-menu-foo-alt">
        <li class="elgg-menu-item elgg-menu-item-baz"></li>
</ul>
<ul class="elgg-menu elgg-menu-foo elgg-menu-foo-default">
        <li class="elgg-menu-item elgg-menu-item-bar"></li>
</ul>

JavaScript ¶

It is common that menu items rely on JavaScript. You can bind client-side events to menu items by placing your JavaScript into AMD module and defining the requirement during the registration.

elgg_register_menu_item('my_menu', array(
        'name' => 'hide_on_click',
        'href' => '#',
        'text' => elgg_echo('hide:on:click'),
        'item_class' => '.hide-on-click',
        'deps' => ['navigation/menu/item/hide_on_click'],
));

// in navigation/menu/item/hide_on_click.js
define(function(require) {
    var $ = require('jquery');

    $(document).on('click', '.hide-on-click', function(e) {
        e.preventDefault();
        $(this).hide();
    });
});

Notifications¶

There are two ways to send notifications in Elgg:

Instant notifications
Event-based notifications send using a notifications queue

Contents

Instant notifications
Enqueued notifications
Registering a new notification method
Sending the notifications using your own method
Subscriptions

Instant notifications ¶

The generic method to send a notification to a user is via the function notify_user(). It is normally used when we want to notify only a single user. Notification like this might for example inform that someone has liked or commented the user’s post.

The function usually gets called in an action file.

Example:¶

In this example a user ($user) is triggering an action to rate a post created by another user ($owner). After saving the rating (ElggAnnotation $rating) to database, we could use the following code to send a notification about the new rating to the owner.

// Subject of the notification
$subject = elgg_echo('ratings:notification:subject', array(), $owner->language);

// Summary of the notification
$summary = elgg_echo('ratings:notification:summary', array($user->name), $owner->language);

// Body of the notification message
$body = elgg_echo('ratings:notification:body', array(
        $user->name,
        $owner->name,
        $rating->getValue() // A value between 1-5
), $owner->language);

$params = array(
        'object' => $rating,
        'action' => 'create',
        'summary' => $summary
);

// Send the notification
notify_user($owner->guid, $user->guid, $subject, $body, $params);

Note

The language used by the recipient isn’t necessarily the same as the language of the person who triggers the notification. Therefore you must always remember to pass the recipient’s language as the third parameter to elgg_echo().

Note

The 'summary' parameter is meant for notification plugins that only want to display a short message instead of both the subject and the body. Therefore the summary should be terse but still contain all necessary information.

Enqueued notifications ¶

On large sites there may be many users who have subscribed to receive notifications about a particular event. Sending notifications immediately when a user triggers such an event might remarkably slow down page loading speed. This is why sending of such notifications shoud be left for Elgg’s notification queue.

New notification events can be registered with the elgg_register_notification_event() function. Notifications about registered events will be sent automatically to all subscribed users.

This is the workflow of the notifications system:

Someone does an action that triggers an event within Elgg

The action can be create, update or delete

The target of the action can be any instance of the ElggEntity class (e.g. a Blog post)

The notifications system saves this event into a notifications queue in the database

When the pluging hook handler for the one-minute interval gets triggered, the event is taken from the queue and it gets processed

Subscriptions are fetched for the user who triggered the event

By default this includes all the users who have enabled any notification method for the user at www.site.com/notifications/personal/<username>

Plugins are allowed to alter the subscriptions using the [get, subscriptions] hook

Plugins are allowed to terminate notifications queue processing with the [send:before, notifications] hook

Plugins are allowed to alter the notification parameters with the [prepare, notification] hook

Plugins are allowed to alter the notification subject/message/summary with the [prepare, notification:<action>:<type>:<subtype>] hook

Plugins are allowed to format notification subject/message/summary for individual delivery methods with [format, notification:<method>] hook

Notifications are sent to each subscriber using the methods they have chosen

Plugins can take over or prevent sending of each individual notification with the [send, notification:<method>] hook

The [send:after, notifications] hook is triggered for the event after all notifications have been sent

Example¶

Tell Elgg to send notifications when a new object of subtype “photo” is created:

/**
 * Initialize the photos plugin
 */
function photos_init() {
        elgg_register_notification_event('object', 'photo', array('create'));
}

Note

In order to send the event-based notifications you must have the one-minute CRON interval configured.

Contents of the notification message can be defined with the 'prepare', 'notification:[action]:[type]:[subtype]' hook.

Example¶

Tell Elgg to use the function photos_prepare_notification() to format the contents of the notification when a new objects of subtype ‘photo’ is created:

/**
 * Initialize the photos plugin
 */
function photos_init() {
    elgg_register_notification_event('object', 'photo', array('create'));
    elgg_register_plugin_hook_handler('prepare', 'notification:create:object:photo', 'photos_prepare_notification');
}

/**
 * Prepare a notification message about a new photo
 *
 * @param string                          $hook         Hook name
 * @param string                          $type         Hook type
 * @param Elgg_Notifications_Notification $notification The notification to prepare
 * @param array                           $params       Hook parameters
 * @return Elgg_Notifications_Notification
 */
function photos_prepare_notification($hook, $type, $notification, $params) {
    $entity = $params['event']->getObject();
    $owner = $params['event']->getActor();
    $recipient = $params['recipient'];
    $language = $params['language'];
    $method = $params['method'];

    // Title for the notification
    $notification->subject = elgg_echo('photos:notify:subject', array($entity->title), $language);

    // Message body for the notification
    $notification->body = elgg_echo('photos:notify:body', array(
        $owner->name,
        $entity->title,
        $entity->getExcerpt(),
        $entity->getURL()
    ), $language);

    // Short summary about the notification
    $notification->summary = elgg_echo('photos:notify:summary', array($entity->title), $language);

    return $notification;
}

Note

Make sure the notification will be in the correct language by passing the reciepient’s language into the elgg_echo() function.

Registering a new notification method ¶

By default Elgg has two notification methods: email and the bundled site_notifications plugin. You can register a new notification method with the elgg_register_notification_method() function.

Example:¶

Register a handler that will send the notifications via SMS.

/**
 * Initialize the plugin
 */
function sms_notifications_init () {
        elgg_register_notification_method('sms');
}

After registering the new method, it will appear to the notification settings page at www.example.com/notifications/personal/[username].

Sending the notifications using your own method ¶

Besides registering the notification method, you also need to register a handler that takes care of actually sending the SMS notifications. This happens with the 'send', 'notification:[method]' hook.

Example:¶

/**
 * Initialize the plugin
 */
function sms_notifications_init () {
        elgg_register_notification_method('sms');
        elgg_register_plugin_hook_handler('send', 'notification:sms', 'sms_notifications_send');
}

/**
 * Send an SMS notification
 *
 * @param string $hook   Hook name
 * @param string $type   Hook type
 * @param bool   $result Has anyone sent a message yet?
 * @param array  $params Hook parameters
 * @return bool
 * @access private
 */
function sms_notifications_send($hook, $type, $result, $params) {
        /* @var Elgg_Notifications_Notification $message */
        $message = $params['notification'];

        $recipient = $message->getRecipient();

        if (!$recipient || !$recipient->mobile) {
                return false;
        }

        // (A pseudo SMS API class)
        $sms = new SmsApi();

        return $sms->send($recipient->mobile, $message->body);
}

Subscriptions ¶

In most cases Elgg core takes care of handling the subscriptions, so notification plugins don’t usually have to alter them.

Subscriptions can however be:

Added using the elgg_add_subscription() function
Removed using the elgg_remove_subscription() function

It’s possible to modify the recipients of a notification dynamically with the 'get', 'subscriptions' hook.

Example:¶

/**
 * Initialize the plugin
 */
function discussion_init() {
        elgg_register_plugin_hook_handler('get', 'subscriptions', 'discussion_get_subscriptions');
}

/**
 * Get subscriptions for group notifications
 *
 * @param string $hook          'get'
 * @param string $type          'subscriptions'
 * @param array  $subscriptions Array containing subscriptions in the form
 *                       <user guid> => array('email', 'site', etc.)
 * @param array  $params        Hook parameters
 * @return array
 */
function discussion_get_subscriptions($hook, $type, $subscriptions, $params) {
        $reply = $params['event']->getObject();

        if (!elgg_instanceof($reply, 'object', 'discussion_reply', 'ElggDiscussionReply')) {
                return $subscriptions;
        }

        $group_guid = $reply->getContainerEntity()->container_guid;
        $group_subscribers = elgg_get_subscriptions_for_container($group_guid);

        return ($subscriptions + $group_subscribers);
}

Page handler¶

Elgg offers a facility to manage your plugin pages via a page handler, enabling custom urls like http://yoursite/your_plugin/section. To add a page handler to a plugin, a handler function needs to be registered in the plugin’s start.php file with elgg_register_page_handler():

elgg_register_page_handler('your_plugin', 'your_plugin_page_handler');

The plugin’s page handler is passed two parameters:

an array containing the sections of the URL exploded by ‘/’. With this information the handler will be able to apply any logic necessary, for example loading the appropriate view and returning its contents.
the handler, this is the handler that is currently used (in our example your_plugin). If you don’t register multiple page handlers to the same function you’ll never need this.

Code flow¶

Pages in plugins should be rendered via page handlers (not by using Elgg\Application). Generally the rendering is done by views with names starting with resources/. The program flow is something like this:

A user requests /plugin_name/section/entity
Elgg checks if plugin_name is registered to a page handler and calls that function, passing array('section', 'entity') as the first argument
The page handler function determines which resource view will display the page.
The handler uses elgg_view_resource() to render the page, also passing in any relevant info to the view via the $vars argument.
The resource view combines many separate views, calls formatting functions like elgg_view_layout() and elgg_view_page(), and then echos the final output
The user sees a fully rendered page

There is no syntax enforced on the URLs, but Elgg’s coding standards suggests a certain format.

Routing¶

Elgg has two mechanisms to respond to HTTP requests that don’t already go through the Actions and Simplecache systems.

URL Identifier and Segments¶

After removing the site URL, Elgg splits the URL path by / into an array. The first element, the identifier, is shifted off, and the remaining elements are called the segments. For example, if the site URL is http://example.com/elgg/, the URL http://example.com/elgg/blog/owner/jane?foo=123 produces:

Identifier: 'blog'. Segments: ['owner', 'jane']. (the query string parameters are available via get_input())

The site URL (home page) is a special case that produces an empty string identifier and an empty segments array.

Warning

URL identifier/segments should be considered potentially dangerous user input. Elgg uses htmlspecialchars to escapes HTML entities in them.

Page Handler¶

To handle all URLs that begin with a particular identifier, you can register a function to act as a Page handler. When the handler is called, the segments array is passed in as the first argument.

The following code registers a page handler for “blog” URLs and shows how one might route the request to a resource view.

elgg_register_page_handler('blog', 'blog_page_handler');

function blog_page_handler(array $segments) {
     // if the URL is http://example.com/elgg/blog/view/123/my-blog-post
     // $segments contains: ['view', '123', 'my-blog-post']

     $subpage = elgg_extract(0, $segments);
     if ($subpage === 'view') {

         // use a view for the page logic to allow other plugins to easily change it
         $resource = elgg_view_resource('blog/view', [
             'guid' => (int)elgg_extract(1, $segments);
         ]);

         return elgg_ok_response($resource);
     }

     // redirect to a different location
     if ($subpage === '') {
         return elgg_redirect_response('blog/all');
     }

     // send an error page
     if ($subpage === 'owner' && !elgg_entity_exists($segments[1])) {
         return elgg_error_response('User not found', 'blog/all', ELGG_HTTP_NOT_FOUND);
     }

     // ... handle other subpages
}

The `route` Plugin Hook¶

The route plugin hook is triggered before page handlers are called. The URL identifier is given as the type of the hook. This hook can be used to add some logic before the request is handled elsewhere, or take over page rendering completely.

Generally devs should instead use a page handler unless they need to affect a single page or a wider variety of URLs.

The following code results in /blog/all requests being completely handled by the plugin hook handler. For these requests the blog page handler is never called.

function myplugin_blog_all_handler($hook, $type, $returnvalue, $params) {
    $segments = elgg_extract('segments', $returnvalue, array());

    if (isset($segments[0]) && $segments[0] === 'all') {
        $title = "We're taking over!";
        $content = elgg_view_layout('one_column', array(
            'title' => $title,
            'content' => "We can take over page rendering completely"
        ));
        echo elgg_view_page($title, $content);

        // in the route hook, return false says, "stop rendering, we've handled this request"
        return false;
    }
}

elgg_register_plugin_hook_handler('route', 'blog', 'myplugin_blog_all_handler');

Note

As of 2.1, route modification should be done in the route:rewrite hook.

The `route:rewrite` Plugin Hook¶

For URL rewriting, the route:rewrite hook (with similar arguments as route) is triggered very early, and allows modifying the request URL path (relative to the Elgg site).

Here we rewrite requests for news/* to blog/*:

function myplugin_rewrite_handler($hook, $type, $value, $params) {
    $value['identifier'] = 'blog';
    return $value;
}

elgg_register_plugin_hook_handler('route:rewrite', 'news', 'myplugin_rewrite_handler');

Warning

The hook must be registered directly in your plugin start.php (the [init, system] event is too late).

Routing overview¶

For regular pages, Elgg’s program flow is something like this:

A user requests http://example.com/news/owner/jane.
Plugins are initialized.
Elgg parses the URL to identifier news and segments ['owner', 'jane'].
Elgg triggers the plugin hook route:rewrite, news (see above).
Elgg triggers the plugin hook route, blog (was rewritten in the rewrite hook).
Elgg finds a registered page handler (see above) for blog, and calls the function, passing in the segments.
The page handler function determines it needs to render a single user’s blog. It calls elgg_view_resource('blog/owner', $vars) where $vars contains the username.
The resources/blog/owner view gets the username via $vars['username'], and uses many other views and formatting functions like elgg_view_layout() and elgg_view_page() to create the entire HTML page.
The page handler echos the view HTML and returns true to indicate it handled the request.
PHP invokes Elgg’s shutdown sequence.
The user receives a fully rendered page.

Elgg’s coding standards suggest a particular URL layout, but there is no syntax enforced.

Services¶

Elgg uses the Elgg\Application class to load and bootstrap Elgg. In future releases this class will offer a set of service objects for plugins to use.

Note

If you have a useful idea, you can add a new service!

Menus¶

elgg()->menus provides low-level methods for constructing menus. In general, menus should be passed to elgg_view_menu for rendering instead of manual rendering.

Page ownership¶

One recurring task of any plugin will be to determine the page ownership in order to decide which actions are allowed or not. Elgg has a number of functions related to page ownership and also offers plugin developers flexibility by letting the plugin handle page ownership requests as well. Determining the owner of a page can be determined with elgg_get_page_owner_guid(), which will return the GUID of the owner. Alternatively, elgg_get_page_owner_entity() will retrieve the whole page owner entity. If the page already knows who the page owner is, but the system doesn’t, the page can set the page owner by passing the GUID to elgg_set_page_owner_guid($guid).

Note

The page owner entity can be any ElggEntity. If you wish to only apply some setting in case of a user or a group make sure you check that you have the correct entity.

Custom page owner handlers¶

Plugin developers can create page owner handlers, which could be necessary in certain cases, for example when integrating third party functionality. The handler will be a function which will need to get registered with elgg_register_plugin_hook_handler('page_owner', 'system', 'your_page_owner_function_name'); . The handler will only need to return a value (an integer GUID) when it knows for certain who the page owner is.

By default, the system uses default_page_owner_handler() to determine the page_owner from the following elements:

The username URL parameter
The owner_guid URL parameter
The URL path

It then passes off to any page owner handlers defined using the plugin hook. If no page owner can be determined, the page owner is set to 0, which is the same as the logged out user.

Permissions Check¶

Warning

As stated in the page, this method works only for granting write access to entities. You cannot use this method to retrieve or view entities for which the user does not have read access.

Elgg provides a mechanism of overriding write permissions check through the permissions_check plugin hook . This is useful for allowing plugin write to all accessible entities regardless of access settings. Entities that are hidden, however, will still be unavailable to the plugin.

Hooking permissions_check¶

In your plugin, you must register the plugin hook for permissions_check.

elgg_register_plugin_hook_handler('permissions_check', 'all', 'myplugin_permissions_check');

The override function¶

Now create the function that will be called by the permissions check hook. In this function we determine if the entity (in parameters) has write access. Since it is important to keep Elgg secure, write access should be given only after checking a variety of situations including page context, logged in user, etc. Note that this function can return 3 values: true if the entity has write access, false if the entity does not, and null if this plugin doesn’t care and the security system should consult other plugins.

function myplugin_permissions_check($hook_name, $entity_type, $return_value, $parameters) {
   $has_access = determine_access_somehow();

   if ($has_access === true) {
      return true;
   } else if ($has_access === false) {
      return false;
   }

   return null;
}

Full Example¶

This is a full example using the context to determine if the entity has write access.

<?php

function myaccess_init() {
   // Register cron hook
   if (!elgg_get_plugin_setting('period', 'myaccess')) {
      elgg_set_plugin_setting('period', 'fiveminute', 'myaccess');
   }

   // override permissions for the myaccess context
   elgg_register_plugin_hook_handler('permissions_check', 'all', 'myaccess_permissions_check');

   elgg_register_plugin_hook_handler('cron', elgg_get_plugin_setting('period', 'myaccess'), 'myaccess_cron');
}

/**
 * Hook for cron event.
 */
function myaccess_cron($event, $object_type, $object) {

   elgg_push_context('myaccess_cron');

   // returns all entities regardless of access permissions.
   // will NOT return hidden entities.
   $entities = get_entities();

   elgg_pop_context();
}

/**
 * Overrides default permissions for the myaccess context
 */
function myaccess_permissions_check($hook_name, $entity_type, $return_value, $parameters) {
   if (elgg_in_context('myaccess_cron')) {
      return true;
   }

   return null;
}

// Initialise plugin
register_elgg_event_handler('init', 'system', 'myaccess_init');
?>

Plugin settings¶

You need to perform some extra steps if your plugin needs settings to be saved and controlled via the administration panel:

Create a file in your plugin’s default view folder called plugins/your_plugin/settings.php, where your_plugin is the name of your plugin’s directory in the mod hierarchy
Fill this file with the form elements you want to display together with internationalised text labels
Set the name attribute in your form components to param[`varname`] where varname is the name of the variable. These will be saved as private settings attached to a plugin entity. So, if your variable is called param[myparameter] your plugin (which is also passed to this view as $vars['entity']) will be called $vars['entity']->myparameter

An example settings.php would look like:

<p>
   <?php echo elgg_echo('myplugin:settings:limit'); ?>

   <select name="params[limit]">
      <option value="5" <?php if ($vars['entity']->limit == 5) echo " selected=\"yes\" "; ?>>5</option>
      <option value="8" <?php if ((!$vars['entity']->limit) || ($vars['entity']->limit == 8)) echo " selected=\"yes\" "; ?>>8</option>
      <option value="12" <?php if ($vars['entity']->limit == 12) echo " selected=\"yes\" "; ?>>12</option>
      <option value="15" <?php if ($vars['entity']->limit == 15) echo " selected=\"yes\" "; ?>>15</option>
   </select>
</p>

Note

You don’t need to add a save button or the form, this will be handled by the framework.

Note

You cannot use form components that send no value when “off.” These include radio inputs and check boxes.

User settings¶

Your plugin might need to store per user settings too, and you would like to have your plugin’s options to appear in the user’s settings page. This is also easy to do and follows the same pattern as setting up the global plugin configuration explained earlier. The only difference is that instead of using a settings file you will use usersettings. So, the path to the user edit view for your plugin would be plugins/your_plugin/usersettings.php.

Note

The title of the usersettings form will default to the plugin name. If you want to change this, add a translation for plugin_id:usersettings:title.

Retrieving settings in your code¶

To retrieve settings from your code use:

$setting = elgg_get_plugin_setting($name, $plugin_id);

or for user settings

$user_setting = elgg_get_plugin_user_setting($name, $user_guid, $plugin_id);

where:

$name Is the value you want to retrieve
$user_guid Is the user you want to retrieve these for (defaults to the currently logged in user)
$plugin_name Is the name of the plugin (detected if run from within a plugin)

Setting values while in code¶

Values may also be set from within your plugin code, to do this use one of the following functions:

elgg_set_plugin_setting($name, $value, $plugin_id);

or

elgg_set_plugin_user_setting($name, $value, $user_guid, $plugin_id);

Warning

The $plugin_id needs to be provided when setting plugin (user)settings.

River¶

Elgg natively supports the “river”, an activity stream containing descriptions of activities performed by site members. This page gives an overview of adding events to the river in an Elgg plugin.

Pushing river items¶

Items are pushed to the activity river through a function call, which you must include in your plugins for the items to appear.

Here we add a river item telling that a user has created a new blog post:

<?php

elgg_create_river_item(array(
        'view' => 'river/object/blog/create',
        'action_type' => 'create',
        'subject_guid' => $blog->owner_guid,
        'object_guid' => $blog->getGUID(),
));

All available parameters:

view => STR The view that will handle the river item (must exist)
action_type => STR An arbitrary string to define the action (e.g. ‘create’, ‘update’, ‘vote’, ‘review’, etc)
subject_guid => INT The GUID of the entity doing the action
object_guid => INT The GUID of the entity being acted upon
target_guid => INT The GUID of the the object entity’s container (optional)
access_id => INT The access ID of the river item (default: same as the object)
posted => INT The UNIX epoch timestamp of the river item (default: now)
annotation_id => INT The annotation ID associated with this river entry (optional)

When an item is deleted or changed, the river item will be updated automatically.

River views¶

In order for events to appear in the river you need to provide a corresponding view with the name specified in the function above.

We recommend /river/{type}/{subtype}/{action}, where:

{type} is the entity type of the content we’re interested in (object for objects, user for users, etc)
{subtype} is the entity subtype of the content we’re interested in (blog for blogs, photo_album for albums, etc)
{action} is the action that took place (‘’create’‘, ‘’update’‘, etc)

River item information will be passed in an object called $vars['item'], which contains the following important parameters:

$vars['item']->subject_guid The GUID of the user performing the action
$vars['item']->object_guid The GUID of the entity being acted upon

Timestamps etc will be generated for you.

For example, the blog plugin uses the following code for its river view:

<?php

$object = $vars['item']->getObjectEntity();

$excerpt = $object->excerpt ? $object->excerpt : $object->description;
$excerpt = strip_tags($excerpt);
$excerpt = elgg_get_excerpt($excerpt);

echo elgg_view('river/elements/layout', array(
        'item' => $vars['item'],
        'message' => $excerpt,
));

Themes¶

Customize the look and feel of Elgg.

A theme is a type of plugin that overrides display aspects of Elgg.

This guide assumes you are familiar with:

Contents

Create your plugin
Customize the CSS
Tools
Customizing the front page

Create your plugin ¶

Create your plugin as described in the developer guide.

Create a new directory under mod/
Create a new start.php
Create a manifest.xml file describing your theme.

Customize the CSS ¶

As of Elgg 1.8, the css is split into several files based on what aspects of the site you’re theming. This allows you to tackle them one at a time, giving you a chance to make real progress without getting overwhelmed.

Here is a list of the existing CSS views:

elements/buttons.css: Provides a way to style all the different kinds of buttons your site will use. There are 5 kinds of buttons that plugins will expect to be available: action, cancel, delete, submit, and special.

elements/chrome.css: This file has some miscellaneous look-and-feel classes.

elements/components.css: This file contains many “css objects” that are used all over the site: media block, list, gallery, table, owner block, system messages, river, tags, photo, and comments.

elements/forms.css: This file determines what your forms and input elements will look like.

elements/icons.css: Contains styles for the icons and avatars used on your site.

elements/layout.css: Determines what your page layout will look like: sidebars, page wrapper, main body, header, footer, etc.

elements/modules.css: Lots of content in Elgg is displayed in boxes with a title and a content body. We called these modules. There are a few kinds: info, aside, featured, dropdown, popup, widget. Widget styles are included in this file too, since they are a subset of modules.

elements/navigation.css: This file determines what all your menus will look like.

elements/typography.css: This file determines what the content and headings of your site will look like.

rtl.css: Custom rules for users viewing your site in a right-to-left language.

admin.css: A completely separate theme for the admin area (usually not overridden).

elgg.css: Compiles all the core elements/* files into one file (DO NOT OVERRIDE).

elements/core.css: Contains base styles for the more complicated “css objects”. If you find yourself wanting to override this, you probably need to report a bug to Elgg core instead (DO NOT OVERRIDE).

elements/reset.css: Contains a reset stylesheet that forces elements to have the same default

View extension ¶

There are two ways you can modify views:

The first way is to add extra stuff to an existing view via the extend view function from within your start.php’s initialization function.

For example, the following start.php will add mytheme/css to Elgg’s core css file:

<?php

    function mytheme_init() {
        elgg_extend_view('elgg.css', 'mytheme/css');
    }

    elgg_register_event_handler('init', 'system', 'mytheme_init');
?>

View overloading ¶

Plugins can have a view hierarchy, any file that exists here will replace any files in the existing core view hierarchy… so for example, if my plugin has a file:

/mod/myplugin/views/default/elements/typography.css

it will replace:

/views/default/elements/typography.css

But only when the plugin is active.

This gives you total control over the way Elgg looks and behaves. It gives you the option to either slightly modify or totally replace existing views.

Icons ¶

As of Elgg 2.0 the default Elgg icons come from the FontAwesome library. You can use any of these icons by calling:

elgg_view_icon('icon-name');

icon-name can be any of the FontAwesome icons without the fa--prefix.

Tools ¶

Starting in Elgg 1.8, we’ve provided you with some development tools to help you with theming: Turn on the “Developers” plugin and go to the “Theme Preview” page to start tracking your theme’s progress.

Customizing the front page ¶

The main Elgg index page runs a plugin hook called ‘index,system’. If this returns true, it assumes that another front page has been drawn and doesn’t display the default page.

Therefore, you can override it by registering a function to the ‘index,system’ plugin hook and then returning true from that function.

Here’s a quick overview:

Create your new plugin
In the start.php you will need something like the following:

<?php

function pluginname_init() {
    // Replace the default index page
    elgg_register_plugin_hook_handler('index', 'system', 'new_index');
}

function new_index() {
    if (!include_once(dirname(dirname(__FILE__)) . "/pluginname/pages/index.php"))
        return false;

    return true;
}

// register for the init, system event when our plugin start.php is loaded
elgg_register_event_handler('init', 'system', 'pluginname_init');
?>

Then, create an index page (/pluginname/pages/index.php) and use that to put the content you would like on the front page of your Elgg site.

Views¶

Contents

Introduction
Using views
Views as templates
Views as cacheable assets
Views and third-party assets
Viewtypes
Altering views via plugins
Displaying entities
Full and partial entity views
Listing entities
Related

Introduction ¶

Views are responsible for creating output. They handle everything from:

the layout of pages

chunks of presentation output (like a footer or a toolbar)

individual links and form inputs.

the images, js, and css needed by your web page

Using views ¶

At their most basic level, the default views are just PHP files with snippets of html:

<h1>Hello, World!</h1>

Assuming this view is located at /views/default/hello.php, we could output it like so:

echo elgg_view('hello');

For your convenience, Elgg comes with quite a lot of views by default. In order to keep things manageable, they are organized into subdirectories. Elgg handles this situation quite nicely. For example, our simple view might live in /views/default/hello/world.php, in which case it would be called like so:

echo elgg_view('hello/world');

The name of the view simply reflects the location of the view in the views directory.

Views as templates ¶

You can pass arbitrary data to a view via the $vars array. Our hello/world view might be modified to accept a variable like so:

<h1>Hello, <?= $vars['name']; ?>!</h1>

In this case, we can pass an arbitrary name parameter to the view like so:

echo elgg_view('hello/world', ['name' => 'World']);

which would produce the following output:

<h1>Hello, World!</h1>

Warning

Views don’t do any kind of automatic output sanitization by default. You are responsible for doing the correct sanitization yourself to prevent XSS attacks and the like.

Views as cacheable assets ¶

As mentioned before, views can contain JS, CSS, or even images.

Asset views must meet certain requirements:

They must not take any $vars parameters

They must not change their output based on global state like

who is logged in

the time of day

They must contain a valid file extension

Bad: my/cool/template

Good: my/cool/template.html

For example, suppose you wanted to load some CSS on a page. You could define a view mystyles.css, which would look like so:

/* /views/default/mystyles.css */
.mystyles-foo {
  background: red;
}

Note

Leave off the trailing “.php” from the filename and Elgg will automatically recognize the view as cacheable.

To get a URL to this file, you would use elgg_get_simplecache_url:

// Returns "https://mysite.com/.../289124335/default/mystyles.css
elgg_get_simplecache_url('mystyles.css');

Elgg automatically adds the magic numbers you see there for cache-busting and sets long-term expires headers on the returned file.

Warning

Elgg may decide to change the location or structure of the returned URL in a future release for whatever reason, and the cache-busting numbers change every time you flush Elgg’s caches, so the exact URL is not stable by design.

With that in mind, here’s a couple anti-patterns to avoid:

Don’t rely on the exact structure/location of this URL

Don’t try to generate the URLs yourself

Don’t store the returned URLs in a database

In your plugin’s init function, register the css file:

elgg_register_css('mystyles', elgg_get_simplecache_url('mystyles.css'));

Then on the page you want to load the css, call:

elgg_load_css('mystyles');

Views and third-party assets ¶

The best way to serve third-party assets is through views. However, instead of manually copy/pasting the assets into the right location in /views/*, you can map the assets into the views system via the "views" key in your plugin’s elgg-plugin.php config file.

The views value must be a 2 dimensional array. The first level maps a viewtype to a list of view mappings. The secondary lists map view names to file paths, either absolute or relative to the Elgg root directory.

If you check your assets into source control, point to them like this:

<?php // mod/example/elgg-plugin.php
return [
    // view mappings
    'views' => [
        // viewtype
        'default' => [
            // view => /path/from/filesystem/root
            'js/jquery-ui.js' => __DIR__ . '/bower_components/jquery-ui/jquery-ui.min.js',
        ],
    ],
];

To point to assets installed with fxp/composer-asset-plugin, use install-root-relative paths by leaving off the leading slash:

<?php // mod/example/elgg-plugin.php
return [
    'views' => [
        'default' => [
            // view => path/from/install/root
            'js/jquery-ui.js' => 'vendor/bower-asset/jquery-ui/jquery-ui.min.js',
        ],
    ],
];

Elgg core uses this feature extensively, though the value is returned directly from /engine/views.php.

Note

You don’t have to use Bower, Composer Asset Plugin, or any other script for managing your plugin’s assets, but we highly recommend using a package manager of some kind because it makes upgrading so much easier.

Specifying additional views directories¶

In elgg-plugin.php you can also specify directories to be scanned for views. Just provide a view name prefix ending with / and a directory path (like above).

<?php // mod/file/elgg-plugin.php
return [
    'views' => [
        'default' => [
            'file/icon/' => __DIR__ . '/graphics/icons',
        ],
    ],
];

With the above, files found within the icons folder will be interpreted as views. E.g. the view file/icon/general.gif will be created and mapped to mod/file/graphics/icons/general.gif.

Note

This is a fully recursive scan. All files found will be brought into the views system.

Multiple paths can share the same prefix, just give an array of paths:

<?php // mod/file/elgg-plugin.php
return [
    'views' => [
        'default' => [
            'file/icon/' => [
                __DIR__ . '/graphics/icons',
                __DIR__ . '/more_icons', // processed 2nd (may override)
            ],
        ],
    ],
];

Viewtypes ¶

You might be wondering: “Why /views/default/hello/world.php instead of just /views/hello/world.php?”.

The subdirectory under /views determines the viewtype of the views below it. A viewtype generally corresponds to the output format of the views.

The default viewtype is assumed to be HTML and other static assets necessary to render a responsive web page in a desktop or mobile browser, but it could also be:

RSS

ATOM

JSON

Mobile-optimized HTML

TV-optimized HTML

Any number of other data formats

You can force Elgg to use a particular viewtype to render the page by setting the view input variable like so: https://mysite.com/?view=rss.

You could also write a plugin to set this automatically using the elgg_set_viewtype() function. For example, your plugin might detect that the page was accessed with an iPhone’s browser string, and set the viewtype to iphone by calling:

elgg_set_viewtype('iphone');

The plugin would presumably also supply a set of views optimized for those devices.

Altering views via plugins ¶

Without modifying Elgg’s core, Elgg provides several ways to customize almost all output:

You can override a view, completely changing the file used to render it.
You can extend a view by prepending or appending the output of another view to it.
You can alter a view’s inputs by plugin hook.
You can alter a view’s output by plugin hook.

Overriding views¶

Views in plugin directories always override views in the core directory; however, when plugins override the views of other plugins, later plugins take precedent.

For example, if we wanted to customize the hello/world view to use an h2 instead of an h1, we could create a file at /mod/example/views/default/hello/world.php like this:

<h2>Hello, <?= $vars['name']; ?></h2>

Note

When considering long-term maintenance, overriding views in the core and bundled plugins has a cost: Upgrades may bring changes in views, and if you have overridden them, you will not get those changes.

You may instead want to alter the input or the output of the view via plugin hooks.

Note

Elgg caches view locations. This means that you should disable the system cache while developing with views. When you install the changes to a production environment you must flush the caches.

Extending views¶

There may be other situations in which you don’t want to override the whole view, you just want to prepend or append some more content to it. In Elgg this is called extending a view.

For example, instead of overriding the hello/world view, we could extend it like so:

elgg_extend_view('hello/world', 'hello/greeting');

If the contents of /views/default/hello/greeting.php is:

<h2>How are you today?</h2>

Then every time we call elgg_view('hello/world');, we’ll get:

<h1>Hello, World!</h1>
<h2>How are you today?</h2>

You can prepend views by passing a value to the 3rd parameter that is less than 500:

// appends 'hello/greeting' to every occurrence of 'hello/world'
elgg_extend_view('hello/world', 'hello/greeting');

// prepends 'hello/greeting' to every occurrence of 'hello/world'
elgg_extend_view('hello/world', 'hello/greeting', 450);

All view extensions should be registered in your plugin’s init,system event handler in start.php.

Altering view input¶

It may be useful to alter a view’s $vars array before the view is rendered.

Since 1.11, before each view rendering the $vars array is filtered by the plugin hook ["view_vars", $view_name]. Each registered handler function is passed these arguments:

$hook - the string "view_vars"
$view_name - the view name being rendered (the first argument passed to elgg_view())
$returnvalue - the modified $vars array
$params - an array containing:
- vars - the original $vars array, unaltered
- view - the view name
- viewtype - The viewtype being rendered

Altering view input example¶

Here we’ll alter the default pagination limit for the comments view:

elgg_register_plugin_hook_handler('view_vars', 'page/elements/comments', 'myplugin_alter_comments_limit');

function myplugin_alter_comments_limit($hook, $type, $vars, $params) {
    // only 10 comments per page
    $vars['limit'] = elgg_extract('limit', $vars, 10);
    return $vars;
}

Altering view output¶

Sometimes it is preferable to alter the output of a view instead of overriding it.

The output of each view is run through the plugin hook ["view", $view_name] before being returned by elgg_view(). Each registered handler function is passed these arguments:

$hook - the string "view"
$view_name - the view name being rendered (the first argument passed to elgg_view())
$result - the modified output of the view
$params - an array containing:
- viewtype - The viewtype being rendered

To alter the view output, the handler just needs to alter $returnvalue and return a new string.

Altering view output example¶

Here we’ll eliminate breadcrumbs that don’t have at least one link.

elgg_register_plugin_hook_handler('view', 'navigation/breadcrumbs', 'myplugin_alter_breadcrumb');

function myplugin_alter_breadcrumb($hook, $type, $returnvalue, $params) {
    // we only want to alter when viewtype is "default"
    if ($params['viewtype'] !== 'default') {
        return $returnvalue;
    }

    // output nothing if the content doesn't have a single link
    if (false === strpos($returnvalue, '<a ')) {
        return '';
    }

    // returning nothing means "don't alter the returnvalue"
}

Replacing view output completely¶

You can pre-set the view output by setting $vars['__view_output']. The value will be returned as a string. View extensions will not be used and the view hook will not be triggered.

elgg_register_plugin_hook_handler('view_vars', 'navigation/breadcrumbs', 'myplugin_no_page_breadcrumbs');

function myplugin_no_page_breadcrumbs($hook, $type, $vars, $params) {
    if (elgg_in_context('pages')) {
        return ['__view_output' => ""];
    }
}

Displaying entities ¶

If you don’t know what an entity is, check this page out first.

The following code will automatically display the entity in $entity:

echo elgg_view_entity($entity);

As you’ll know from the data model introduction, all entities have a type (object, site, user or group), and optionally a subtype (which could be anything - ‘blog’, ‘forumpost’, ‘banana’).

elgg_view_entity will automatically look for a view called type/subtype; if there’s no subtype, it will look for type/type. Failing that, before it gives up completely it tries type/default.

RSS feeds in Elgg generally work by outputting the object/default view in the ‘rss’ viewtype.

For example, the view to display a blog post might be object/blog. The view to display a user is user/default.

Full and partial entity views ¶

elgg_view_entity actually has a number of parameters, although only the very first one is required. The first three are:

$entity - The entity to display
$viewtype - The viewtype to display in (defaults to the one we’re currently in, but it can be forced - eg to display a snippet of RSS within an HTML page)
$full_view - Whether to display a full version of the entity. (Defaults to false.)

This last parameter is passed to the view as $vars['full_view']. It’s up to you what you do with it; the usual behaviour is to only display comments and similar information if this is set to true.

Listing entities ¶

This is then used in the provided listing functions. To automatically display a list of blog posts (see the full tutorial), you can call:

echo elgg_list_entities([
    'type' => 'object',
    'subtype' => 'blog',
]);

This function checks to see if there are any entities; if there are, it first displays the navigation/pagination view in order to display a way to move from page to page. It then repeatedly calls elgg_view_entity on each entity before returning the result.

Note that elgg_list_entities allows the URL to set its limit and offset options, so set those explicitly if you need particular values (e.g. if you’re not using it for pagination).

Elgg knows that it can automatically supply an RSS feed on pages that use elgg_list_entities. It initializes the ["head","page"] plugin hook (which is used by the header) in order to provide RSS autodiscovery, which is why you can see the orange RSS icon on those pages in some browsers.

If your entity list will display the entity owners, you can improve performance a bit by preloading all owner entities:

echo elgg_list_entities([
    'type' => 'object',
    'subtype' => 'blog',

    // enable owner preloading
    'preload_owners' => true,
]);

If you want to show a message when the list does not contain items to list, you can pass a no_results message. If you want even more controle over the no_results message you can also pass a Closure (an anonymous function).

echo elgg_list_entities([
    'type' => 'object',
    'subtype' => 'blog',

    'no_results' => elgg_echo('notfound'),
]);

Rendering a list with an alternate view¶

Since 1.11, you can define an alternative view to render list items using 'item_view' parameter.

In some cases, default entity views may be unsuitable for your needs. Using item_view allows you to customize the look, while preserving pagination, list’s HTML markup etc.

Consider these two examples:

echo elgg_list_entities_from_relationship([
    'type' => 'group',
    'relationship' => 'member',
    'relationship_guid' => elgg_get_logged_in_user_guid(),
    'inverse_relationship' => false,
    'full_view' => false,
]);

echo elgg_list_entities_from_relationship([
    'type' => 'group',
    'relationship' => 'invited',
    'relationship_guid' => (int) $user_guid,
    'inverse_relationship' => true,
    'item_view' => 'group/format/invitationrequest',
]);

In the first example, we are displaying a list of groups a user is a member of using the default group view. In the second example, we want to display a list of groups the user was invited to.

Since invitations are not entities, they do not have their own views and can not be listed using elgg_list_*. We are providing an alternative item view, that will use the group entity to display an invitation that contains a group name and buttons to access or reject the invitation.

Rendering a list as a table¶

Since 2.3 you can render lists as tables. Set $options['list_type'] = 'table' and provide an array of TableColumn objects as $options['columns']. The service elgg()->table_columns provides several methods to create column objects based around existing views (like page/components/column/*), properties, or methods.

In this example, we list the latest my_plugin objects in a table of 3 columns: entity icon, the display name, and a friendly format of the time.

echo elgg_list_entities([
    'type' => 'object',
    'subtype' => 'my_plugin',

    'list_type' => 'table',
    'columns' => [
        elgg()->table_columns->icon(),
        elgg()->table_columns->getDisplayName(),
        elgg()->table_columns->time_created(null, [
            'format' => 'friendly',
        ]),
    ],
]);

See the Elgg\Views\TableColumn\ColumnFactory class for more details on how columns are specified and rendered. You can add or override methods of elgg()->table_columns in a variety of ways, based on views, properties/methods on the items, or given functions.

Widgets¶

Widgets are content areas that users can drag around their page to customize the layout. They can typically be customized by their owner to show more/less content and determine who sees the widget. By default Elgg provides plugins for customizing the profile page and dashboard via widgets.

TODO: Screenshot

Contents

Structure
Register the widget
Default widgets

Structure ¶

To create a widget, create two views:

widgets/widget/edit
widgets/widget/content

content.php is responsible for all the content that will output within the widget. The edit.php file contains any extra edit functions you wish to present to the user. You do not need to add access level as this comes as part of the widget framework.

Note

Using HTML checkboxes to set widget flags is problematic because if unchecked, the checkbox input is omitted from form submission. The effect is that you can only set and not clear flags. The “input/checkboxes” view will not work properly in a widget’s edit panel.

Register the widget ¶

Once you have created your edit and view pages, you need to initialize the plugin widget. This is done within the plugins init() function.

// Add generic new file widget
elgg_register_widget_type([
    'id' => 'filerepo',
    'name' => elgg_echo('widgets:filerepo:name'),
    'description' => elgg_echo('widgets:filerepo:description'),
]);

Note

The only required attribute is the id.

Multiple widgets ¶

It is possible to add multiple widgets for a plugin. You just initialize as many widget directories as you need.

 // Add generic new file widget
 elgg_register_widget_type([
     'id' => 'filerepo',
     'name' => elgg_echo('widgets:filerepo:name'),
     'description' => elgg_echo('widgets:filerepo:description'),
 ]);

 // Add a second file widget
elgg_register_widget_type([
     'id' => 'filerepo2',
     'name' => elgg_echo('widgets:filerepo2:name'),
     'description' => elgg_echo('widgets:filerepo2:description'),
 ]);

 // Add a third file widget
elgg_register_widget_type([
     'id' => 'filerepo3',
     'name' => elgg_echo('widgets:filerepo3:name'),
     'description' => elgg_echo('widgets:filerepo3:description'),
 ]);

Make sure you have the corresponding directories within your plugin views structure:

'Plugin'
    /views
        /default
            /widgets
               /filerepo
                  /edit.php
                  /content.php
               /filerepo2
                  /edit.php
                  /content.php
               /filerepo3
                  /edit.php
                  /content.php

How to restrict where widgets can be used ¶

The widget can specify the context that it can be used in (all, just profile, just dashboard, etc.). If you do not specify a context they will be available for all contexts.

elgg_register_widget_type([
    'id' => 'filerepo',
    'context' => ['profile', 'dashboard', 'other_context'],
]);

Allow multiple widgets on the same page ¶

By default you can only add one widget of the same type on the page. If you want more of the same widget on the page, you can specify this when registering the widget:

elgg_register_widget_type([
    'id' => 'filerepo',
    'multiple' => true,
]);

Register widgets in a hook ¶

If, for example, you wish to conditionally register widgets you can also use a hook to register widgets.

function my_plugin_init() {
    elgg_register_plugin_hook_handler('handlers', 'widgets', 'my_plugin_conditional_widgets_hook');
}

function my_plugin_conditional_widgets_hook($hook, $type, $return, $params) {
    if (!elgg_is_active_plugin('file')) {
        return;
    }

    $return[] = \Elgg\WidgetDefinition::factory([
        'id' => 'filerepo',
    ]);

    return $return;
}

Modify widget properties of existing widget registration ¶

If, for example, you wish to change the allowed contexts of an already registered widget you can do so by re-registering the widget with elgg_register_widget_type as it will override an already existing widget definition. If you want even more control you can also use the handlers, widgets hook to change the widget definition.

function my_plugin_init() {
    elgg_register_plugin_hook_handler('handlers', 'widgets', 'my_plugin_change_widget_definition_hook');
}

function my_plugin_change_widget_definition_hook($hook, $type, $return, $params) {
    foreach ($return as $key => $widget) {
        if ($widget->id === 'filerepo') {
            $return[$key]->multiple = false;
        }
    }

    return $return;
}

Default widgets ¶

If your plugin uses the widget canvas, you can register default widget support with Elgg core, which will handle everything else.

To announce default widget support in your plugin, register for the get_list, default_widgets plugin hook:

elgg_register_plugin_hook_handler('get_list', 'default_widgets', 'my_plugin_default_widgets_hook');

In the plugin hook handler, push an array into the return value defining your default widget support and when to create default widgets. Arrays require the following keys to be defined:

name - The name of the widgets page. This is displayed on the tab in the admin interface.
widget_context - The context the widgets page is called from. (If not explicitly set, this is your plugin’s id.)
widget_columns - How many columns the widgets page will use.
event - The Elgg event to create new widgets for. This is usually create.
entity_type - The entity type to create new widgets for.
entity_subtype - The entity subtype to create new widgets for. The can be ELGG_ENTITIES_ANY_VALUE to create for all entity types.

When an object triggers an event that matches the event, entity_type, and entity_subtype parameters passed, Elgg core will look for default widgets that match the widget_context and will copy them to that object’s owner_guid and container_guid. All widget settings will also be copied.

function my_plugin_default_widgets_hook($hook, $type, $return, $params) {
    $return[] = array(
        'name' => elgg_echo('my_plugin'),
        'widget_context' => 'my_plugin',
        'widget_columns' => 3,

        'event' => 'create',
        'entity_type' => 'user',
        'entity_subtype' => ELGG_ENTITIES_ANY_VALUE,
    );

    return $return;
}

Walled Garden¶

Elgg supports a “Walled Garden” mode. In this mode, almost all pages are restricted to logged in users. This is useful for sites that don’t allow public registration.

Activating Walled Garden mode¶

To activate Walled Garden mode in Elgg 1.8, go to the Administration section. On the right sidebar menu, under the “Configure” section, expand “Settings,” then click on “Advanced.”

From the Advanced Settings page, find the option labelled “Restrict pages to logged-in users.” Enable this option, then click “Save” to switch your site into Walled Garden mode.

Exposing pages through Walled Gardens¶

Many plugins extend Elgg by adding pages. Walled Garden mode will prevent these pages from being viewed by logged out users. Elgg uses plugin hook to manage which pages are visible through the Walled Garden.

Plugin authors must register pages as public if they should be viewable through Walled Gardens by responding to the public_pages, walled_garden plugin hook.

The returned value is an array of regexp expressions for public pages.

The following code shows how to expose http://example.org/my_plugin/public_page through a Walled Garden. This assumes the plugin has registered a Page handler for my_plugin.

elgg_register_plugin_hook_handler('public_pages', 'walled_garden', 'my_plugin_walled_garden_public_pages');

function my_plugin_walled_garden_public_pages($hook, $type, $pages) {
   $pages[] = 'my_plugin/public_page';
   return $pages;
}

Web services¶

Build an HTTP API for your site.

Elgg provides a powerful framework for building web services. This allows developers to expose functionality to other web sites and desktop applications along with doing integrations with third-party web applications. While we call the API RESTful, it is actually a REST/RPC hybrid similar to the APIs provided by sites like Flickr and Twitter.

To create an API for your Elgg site, you need to do 4 things:

enable the web services plugin
expose methods
setup API authentication
setup user authentication

Additionally, you may want to control what types of authentication are available on your site. This will also be covered.

Contents

Security
Exposing methods
API authentication
User authentication
Building out your API
Determining the authentication available
Related

Security ¶

It is crucial that the web services are consumed via secure protocols. Do not enable web services if your site is not served via HTTPs. This is especially important if you allow API key only authentication.

If you are using third-party tools that expose API methods, make sure to carry out a thorough security audit. You may want to make sure that API authentication is required for ALL methods, even if they require user authentication. Methods that do not require API authentication can be easily abused to spam your site.

Ensure that the validity of API keys is limited and provide mechanisms for your API clients to renew their keys.

Exposing methods ¶

The function to use to expose a method is elgg_ws_expose_function(). As an example, let’s assume you want to expose a function that echos text back to the calling application. The function could look like this

function my_echo($string) {
    return $string;
}

Since we are providing this function to allow developers to test their API clients, we will require neither API authentication nor user authentication. This call registers the function with the web services API framework:

elgg_ws_expose_function(
        "test.echo",
        "my_echo",
        [
                "string" => [
                        'type' => 'string',
                ]
        ],
        'A testing method which echos back a string',
        'GET',
        false,
        false
);

If you add this code to a plugin and then go to http://yoursite.com/services/api/rest/json/?method=system.api.list, you should now see your test.echo method listed as an API call. Further, to test the exposed method from a web browser, you could hit the url: http://yoursite.com/services/api/rest/json/?method=test.echo&string=testing and you should see JSON data like this:

{"status":0,"result":"testing"}

Plugins can filter the output of individual API methods by registering a handler for 'rest:output',$method plugin hook.

Response formats ¶

JSON is the default format, however XML and serialized PHP can be fetched by enabling the data_views plugin and substituting xml or php in place of json in the above URLs.

You can also add additional response formats by defining new viewtypes.

Parameters ¶

Parameters expected by each method should be listed as an associative array, where the key represents the parameter name, and the value contains an array with type, default and required fields.

Values submitted with the API request for each parameter should match the declared type. API will throw on exception if validation fails.

Recognized parameter types are:

integer (or int)

boolean (or bool)

string

float

array

Unrecognized types will throw an API exception.

You can use additional fields to describe your parameter, e.g. description.

elgg_ws_expose_function(
        'test.greet',
        'my_greeting',
        [
                'name' => [
                        'type' => 'string',
                        'required' => true,
                        'description' => 'Name of the person to be greeted by the API',
                ],
                'greeting' => [
                        'type' => 'string',
                        'required' => false,
                        'default' => 'Hello',
                        'description' => 'Greeting to be used, e.g. "Good day" or "Hi"',
                ],
        ],
        'A testing method which greets the user with a custom greeting',
        'GET',
        false,
        false
);

Note

If a missing parameter has no default value, the argument will be null. Before 2.1, a bug caused later arguments to be shifted left in this case.

Receive parameters as associative array ¶

If you have a large number of method parameters, you can force the execution script to invoke the callback function with a single argument that contains an associative array of parameter => input pairs (instead of each parameter being a separate argument). To do that, set $assoc to true in elgg_ws_expose_function().

function greet_me($values) {
        $name = elgg_extract('name', $values);
        $greeting = elgg_extract('greeting', $values, 'Hello');
        return "$greeting, $name";
}

elgg_ws_expose_function(
        "test.greet",
        "greet_me",
        [
                "name" => [
                        'type' => 'string',
                ],
                "greeting" => [
                        'type' => 'string',
                        'default' => 'Hello',
                        'required' => false,
                ],
        ],
        'A testing method which echos a greeting',
        'GET',
        false,
        false,
        true // $assoc makes the callback receive an associative array
);

Note

If a missing parameter has no default value, null will be used.

API authentication ¶

You may want to control access to some of the functions that you expose. Perhaps you are exposing functions in order to integrate Elgg with another open source platform on the same server. In that case, you only want to allow that other application access to these methods. Another possibility is that you want to limit what external developers have access to your API. Or maybe you want to limit how many calls a developer can make against your API in a single day.

In all of these cases, you can use Elgg’s API authentication functions to control access. Elgg provides two built-in methods to perform API authentication: key based and HMAC signature based. You can also add your own authentication methods. The key based approach is very similar to what Google, Flickr, or Twitter. Developers can request a key (a random string) and pass that key with all calls that require API authentication. The keys are stored in the database and if an API call is made without a key or a bad key, the call is denied and an error message is returned.

Key-based authentication ¶

As an example, let’s write a function that returns the number of users that have viewed the site in the last x minutes.

function count_active_users($minutes=10) {
    $seconds = 60 * $minutes;
    $count = count(find_active_users($seconds, 9999));
    return $count;
}

Now, let’s expose it and make the number of minutes an optional parameter:

elgg_ws_expose_function(
        "users.active",
        "count_active_users",
        [
                "minutes" => [
                        'type' => 'int',
                        'required' => false,
                ],
        ],
        'Number of users who have used the site in the past x minutes',
        'GET',
        true,
        false
);

This function is now available and if you check system.api.list, you will see that it requires API authentication. If you hit the method with a web browser, it will return an error message about failing the API authentication. To test this method, you need an API key. Fortunately, there is a plugin called apiadmin that creates keys for you. It is available in the Elgg plugin repository. It will return a public and private key and you will use the public key for this kind of API authentication. Grab a key and then do a GET request with your browser on this API method passing in the key string as the parameter api_key. It might look something like this: http://yoursite.com/services/api/rest/xml/?method=users.active&api_key=1140321cb56c71710c38feefdf72bc462938f59f.

Signature-based authentication ¶

The HMAC Authentication is similar to what is used with OAuth or Amazon’s S3 service. This involves both the public and private key. If you want to be very sure that the API calls are coming from the developer you think they are coming from and you want to make sure the data is not being tampered with during transmission, you would use this authentication method. Be aware that it is much more involved and could turn off developers when there are other sites out there with key-based authentication.

OAuth ¶

With the addition of the OAuth plugin, Elgg also fully supports the OAuth 1.0a authorization standard. Clients can then use standard OAuth libraries to make any API calls to the site.

User authentication ¶

So far you have been allowing developers to pull data out of your Elgg site. Now we’ll move on to pushing data into Elgg. In this case, it is going to be done by a user. Maybe you have created a desktop application that allows your Users to post to the wire without going to the site. You need to expose a method for posting to the wire and you need to make sure that a user cannot post using someone else’s account. Elgg provides a token-based approach for user authentication. It allows a user to submit their username and password in exchange for a token using the method auth.gettoken. This token can then be used for some amount of time to authenticate all calls to the API before it expires by passing it as the parameter auth_token. If you do not want to have your users trusting their passwords to 3rd-party applications, you can also extend the current capability to use an approach like OAuth.

Let’s write our wire posting function:

function my_post_to_wire($text) {

    $text = substr($text, 0, 140);

    $access = ACCESS_PUBLIC;

    // returns guid of wire post
    return thewire_save_post($text, $access, "api");
}

Exposing this function is the same as the previous except we require user authentication and we’re going to make this use POST rather than GET HTTP requests.

elgg_ws_expose_function(
        "thewire.post",
        "my_post_to_wire",
        [
                "text" => [
                        'type' => 'string',
                ],
        ],
        'Post to the wire. 140 characters or less',
        'POST',
        true,
        true
);

Please note that you will not be able to test this using a web browser as you did with the other methods. You need to write some client code to do this. There is some example client code in /engine/lib/api.php. Take a look at send_api_post_call(). You can also do a search for clients that have been written for the APIs of Flickr or Twitter or any other similar API. You will find a wide variety written in almost any language you can think of.

Building out your API ¶

As soon as you feel comfortable with Elgg’s web services API framework, you will want to step back and design your API. What sort of data are you trying to expose? Who or what will be API users? How do you want them to get access to authentication keys? How are you going to document your API? Be sure to take a look at the APIs created by popular Web 2.0 sites for inspiration. If you are looking for 3rd party developers to build applications using your API, you will probably want to provide one or more language-specific clients.

Determining the authentication available ¶

Elgg’s web services API uses a type of pluggable authentication module (PAM) architecture to manage how users and developers are authenticated. This provides you the flexibility to add and remove authentication modules. Do you want to not use the default user authentication PAM but would prefer using OAuth? You can do this.

The first step is registering a callback function for the rest, init plugin hook:

register_plugin_hook('rest', 'init', 'rest_plugin_setup_pams');

Then in the callback function, you register the PAMs that you want to use:

function rest_plugin_setup_pams() {
    // user token can also be used for user authentication
    register_pam_handler('pam_auth_usertoken');

    // simple API key check
    register_pam_handler('api_auth_key', "sufficient", "api");

    // override the default pams
    return true;
}

When testing, you may find it useful to register the pam_auth_session PAM so that you can easily test your methods from the browser. Be careful not to use this PAM on a production site because it could open up your users to a CSRF attack.

Right now, the only other PAMs publicly available besides those provided by the Elgg core are the OAuth PAMs. See Justin Richer’s OAuth plugin for more detail.

Upgrading Plugins¶

Prepare your plugin for the next version of Elgg.

See the administrator guides for how to upgrade a live site.

Contents

From 2.2 to 2.3
From 2.1 to 2.2
From 2.0 to 2.1
From 1.x to 2.0
From 1.10 to 1.11
- Comment highlighting
From 1.9 to 1.10
- File uploads
From 1.8 to 1.9
From 1.7 to 1.8
- Updating core
- Updating plugins

From 2.2 to 2.3 ¶

PHP Version ¶

PHP 5.5 has reached end of life in July 2016. To ensure that Elgg sites are secure, we now require PHP 5.6 for new installations.

Existing installations can continue using PHP 5.5 until Elgg 3.0.

In order to upgrade Elgg to 2.3 using composer while using PHP 5.5, you may need to use --ignore-platform-reqs flag.

Deprecated APIs ¶

Registering for to:object hook by the extender name: Use to:object, annotation and to:object, metadata hooks instead.

ajax_forward_hook(): No longer used as handler for ‘forward’,’all’ hook. Ajax response is now wrapped by the ResponseFactory

ajax_action_hook(): No longer used as handler for ‘action’,’all’ hook. Output buffering now starts before the hook is triggered in ActionsService

elgg_error_page_handler(): No longer used as a handler for ‘forward’,<error_code> hooks

get_uploaded_file(): Use new file uploads API instead

get_user_notification_settings(): Use ElggUser::getNotificationSettings()

set_user_notification_setting(): Use ElggUser::setNotificationSetting()

pagesetup, system event: Use the menu or page shell hooks instead.

elgg.walled_garden JavaScript is deprecated: Use elgg/walled_garden AMD module instead.

elgg()->getDb()->getTableprefix(): Use elgg_get_config('dbprefix').

Private update_entity_last_action(): Refrain from manually updating last action timestamp.

Setting non-public access_id on metadata is deprecated. See below.

get_resized_image_from_existing_file(): Use elgg_save_resized_image().

get_resized_image_from_uploaded_file(): Use elgg_save_resized_image() in combination with upload API.

get_image_resize_parameters() will be removed.

elgg_view_input(): Use elgg_view_field(). Apologies for the API churn.

Deprecated Views ¶

resources/file/world: Use the resources/file/all view instead.

resources/pages/world: Use the resources/pages/all view instead.

walled_garden.js: Use the elgg/walled_garden module instead.

New API for page and action handling ¶

Page handlers and action script files should now return an instance of \Elgg\Http\ResponseBuilder. Plugins should use the following convenience functions to build responses:

elgg_ok_response() sends a 2xx response with HTML (page handler) or JSON data (actions)

elgg_error_response() sends a 4xx or 5xx response without content/data

elgg_redirect_response() silently redirects the request

New API for working with file uploads ¶

elgg_get_uploaded_files() - returns an array of Symfony uploaded file objects

ElggFile::acceptUploadedFile() - moves an uploaded file to Elgg’s filestore

New API for manipulating images ¶

New image manipulation service implements a more efficient approach to cropping and resizing images.

elgg_save_resized_image() - crops and resizes an image to preferred dimensions

New API for events ¶

elgg_clear_event_handlers() - similar to elgg_clear_plugin_hook_handlers this functions removes all registered event handlers

New API for signing URLs ¶

URLs can now be signed with a SHA-256 HMAC key and validated at any time before URL expiry. This feature can be used to tokenize action URLs in email notifications, as well as other uses outside of the Elgg installation.

elgg_http_get_signed_url() - signs the URL with HMAC key

elgg_http_validate_signed_url() - validates the signed URL

elgg_signed_request_gatekeeper() - gatekeeper that validates the signature of the current request

Extendable form views ¶

Form footer rendering can now be deferred until the form view and its extensions have finished rendering. This allows plugins to collaborate on form views without breaking the markup logic.

elgg_set_form_footer() - sets form footer for deferred rendering

elgg_get_form_footer() - returns currently set form footer

Metadata `access_id`¶

It’s now deprecated to create metadata with an explicit access_id value other than ACCESS_PUBLIC.

In Elgg 3.0, metadata will not be access controlled, and will be available in all contexts. If your plugin relies on access control of metadata, it would be wise to migrate storage to annotations or entities instead.

New API for extracting class names from arrays ¶

Similar to elgg_extract(), elgg_extract_class() extracts the “class” key (if present), merges into existing class names, and always returns an array.

Notifications ¶

A high level 'prepare','notification' hook is now triggered for instant and subscription notifications and can be used to alter notification objects irrespective of their type.

'format','notification:<method>' hook is now triggered for instant and subscription notifications and can be used to format the notification (e.g. strip HTML tags, wrap the notification body in a template etc).

Instant notifications are now handled by the notifications service, hence almost all hooks applicable to subscription notifications also apply to instant notifications.

elgg_get_notification_methods() can be used to obtain registered notification methods

Added ElggUser::getNotificationSettings() and ElggUser::setNotificationSetting()

Entity list functions can output tables ¶

In functions like elgg_list_entities($options), table output is possible by setting $options['list_type'] = 'table' and providing an array of table columns as $options['columns']. Each column is an Elgg\Views\TableColumn object, usually created via methods on the service elgg()->table_columns.

Plugins can provide or alter these factory methods (see Elgg\Views\TableColumn\ColumnFactory). See the view admin/users/newest for a usage example.

Inline tabs components ¶

Inline tabs component can now be rendered with page/components/tabs view. The components allows to switch between pre-poluated and ajax-loaded. See page/components/tabs in core views and theme_sandbox/components/tabs in developers plugin for usage instructions and examples.

API to alter registration and login URL ¶

elgg_get_registration_url() should be used to obtain site’s registration URL

elgg_get_login_url() should be used to obtain site’s login URL

registration_url, site hook can be used to alter the default registration URL

login_url, site hook can be used to alter the default login URL

Support for fieldsets in forms ¶

elgg_view_field() replaces elgg_view_input(). It has a similar API, but accepts a single array.

elgg_view_field() supports #type, #label, #help and #class, allowing unprefixed versions to be sent to the input view $vars.

The new view input/fieldset can be used to render a set of fields, each rendered with elgg_view_field().

From 2.1 to 2.2 ¶

Deprecated APIs ¶

elgg.ui.river JavaScript library: Remove calls to elgg_load_js('elgg.ui.river') from plugin code. Update core/river/filter and forms/comment/save, if overwritten, to require component AMD modules

elgg.ui.popupOpen() and elgg.ui.popupClose() methods in elgg.ui JS library: Use elgg/popup module instead.

lightbox.js library: Do not use elgg_load_js('lightbox.js'); unless your code references deprecated elgg.ui.lightbox namespace. Use elgg/lightbox AMD module instead.

elgg.embed library and elgg.embed object: Do not use elgg_load_js('elgg.embed'). Use elgg/embed AMD module instead

Accessing icons_sizes config value directly: Use elgg_get_icon_sizes()

can_write_to_container(): Use ElggEntity::canWriteToContainer()

Deprecated Views ¶

elgg/ui.river.js is deprecated: Do not rely on simplecache URLs to work.

groups/js is deprecated: Use groups/navigation AMD module as a menu item dependency for “feature” and “unfeature” menu items instead.

lightbox/settings.js is deprecated: Use getOptions, ui.lightbox JS plugin hook or data-colorbox-opts attribute.

elgg/ckeditor/insert.js is deprecated: You no longer need to include it, hook registration takes place in elgg/ckeditor module

embed/embed.js is deprecated: Use elgg/embed AMD module.

Added `elgg/embed` module ¶

Even though rarely necessary, elgg/embed AMD module can be used to access the embed methods programmatically. The module bootstraps itself when necessary and is unlikely to require further decoration.

New API for handling entity icons ¶

ElggEntity now implements \Elgg\EntityIcon interface

elgg_get_icon_sizes() - return entity type/subtype specific icon sizes

ElggEntity::saveIconFromUploadedFile() - creates icons from an uploaded file

ElggEntity::saveIconFromLocalFile() - creates icons from a local file

ElggEntity::saveIconFromElggFile() - creates icons from an instance of ElggFile

ElggEntity::getIcon() - returns an instanceof ElggIcon that points to entity icon location on filestore (this may be just a placeholder, use ElggEntity::hasIcon() to validate if file has been written)

ElggEntity::deleteIcon() - deletes entity icons

ElggEntity::getIconLastChange() - return modified time of the icon file

ElggEntity::hasIcon() - checks if an icon with given size has been created

elgg_get_embed_url() - can be used to return an embed URL for an entity’s icon (served via /serve-icon handler)

User avatars are now served via serve-file handler. Plugins should start using elgg_get_inline_url() and note that:

/avatar/view page handler and resource view have been deprecated

/mod/profile/icondirect.php file has been deprecated

profile_set_icon_url() is no longer registered as a callback for "entity:icon:url","user" plugin hook

Group avatars are now served via serve-file handler. Plugins should start using elgg_get_inline_url() and note that:

groupicon page handler (groups_icon_handler()) has been deprecated

/mod/groups/icon.php file has been deprecated

File entity thumbs and downloads are now served via serve-file handler. Plugins should start using elgg_get_inline_url() and elgg_get_download_url() and note that:

file/download page handler and resource view have been deprecated

mod/file/thumbnail.php file has been deprecated

Several views have been updated to use new download URLs, including:

mod/file/views/default/file/specialcontent/audio/default.php

mod/file/views/default/file/specialcontent/image/default.php

mod/file/views/default/resources/file/view.php

mod/file/views/rss/file/enclosure.php

Removed APIs ¶

Just a warning that the private entity cache functions (e.g. _elgg_retrieve_cached_entity) have been removed. Some plugins may have been using them. Plugins should not use private APIs as they will more often be removed without notice.

Improved `elgg/ckeditor` module ¶

elgg/ckeditor module can now be used to add WYSIWYG to a textarea programmatically with elgg/ckeditor#bind.

From 2.0 to 2.1 ¶

Deprecated APIs ¶

ElggFile::setFilestore

get_default_filestore

set_default_filestore

elgg_get_config('siteemail'): Use elgg_get_site_entity()->email

URLs starting with /css/ and /js/: Use elgg_get_simplecache_url()

elgg.ui.widgets JavaScript object is deprecated by elgg/widgets AMD module

`Application::getDb()` changes ¶

If you’re using this low-level API, do not expect it to return an Elgg\Database instance in 3.0. It now returns an Elgg\Application\Database with many deprecated. These methods were never meant to be made public API, but we will do our best to support them in 2.x.

Added `elgg/widgets` module ¶

If your plugin code calls elgg.ui.widgets.init(), instead use the elgg/widgets module.

From 1.x to 2.0 ¶

Elgg can be now installed as a composer dependency instead of at document root ¶

That means an Elgg site can look something like this:

settings.php
vendor/
  elgg/
    elgg/
      engine/
        start.php
      _graphics/
        elgg_sprites.png
mod/
  blog
  bookmarks
  ...

elgg_get_root_path and $CONFIG->path will return the path to the application root directory, which is not necessarily the same as Elgg core’s root directory (which in this case is vendor/elgg/elgg/).

Do not attempt to access the core Elgg from your plugin directly, since you cannot rely on its location on the filesystem.

In particular, don’t try load engine/start.php.

// Don't do this!
dirname(__DIR__) . "/engine/start.php";

To boot Elgg manually, you can use the class Elgg\Application.

// boot Elgg in mod/myplugin/foo.php
require_once dirname(dirname(__DIR__)) . '/vendor/autoload.php';
\Elgg\Application::start();

However, use this approach sparingly. Prefer Routing instead whenever possible as that keeps your public URLs and your filesystem layout decoupled.

Also, don’t try to access the _graphics files directly.

readfile(elgg_get_root_path() . "_graphics/elgg_sprites.png");

Use Views instead:

echo elgg_view('elgg_sprites.png');

Cacheable views must have a file extension in their names ¶

This requirement makes it possibile for us to serve assets directly from disk for performance, instead of serving them through PHP.

It also makes it much easier to explore the available cached resources by navigating to dataroot/views_simplecache and browsing around.

Bad: my/cool/template

Good: my/cool/template.html

We now cache assets by "$viewtype/$view", not md5("$viewtype|$view"), which can result in conflicts between cacheable views that don’t have file extensions to disambiguate files from directories.

Dropped `jquery-migrate` and upgraded `jquery` to ^2.1.4 ¶

jQuery 2.x is API-compatible with 1.x, but drops support for IE8-, which Elgg hasn’t supported for some time anyways.

See http://jquery.com/upgrade-guide/1.9/ for how to move off jquery-migrate.

If you’d prefer to just add it back, you can use this code in your plugin’s init:

elgg_register_js('jquery-migrate', elgg_get_simplecache_url('jquery-migrate.js'), 'head');
elgg_load_js('jquery-migrate');

Also, define a jquery-migrate.js view containing the contents of the script.

JS and CSS views have been moved out of the js/ and css/ directories ¶

They also have been given .js and .css extensions respectively if they didn’t already have them:

Old view	New view
`js/view`	`view.js`
`js/other.js`	`other.js`
`css/view`	`view.css`
`css/other.css`	`other.css`
`js/img.png`	`img.png`

The main benefit this brings is being able to co-locate related assets. So a template (view.php) can have its CSS/JS dependencies right next to it (view.css, view.js).

Care has been taken to make this change as backwards-compatible as possible, so you should not need to update any view references right away. However, you are certainly encouraged to move your JS and CSS views to their new, canonical locations.

Practically speaking, this carries a few gotchas:

The view_vars, $view_name and view, $view_name hooks will operate on the canonical view name:

elgg_register_plugin_hook_handler('view', 'css/elgg', function($hook, $view_name) {
  assert($view_name == 'elgg.css') // not "css/elgg"
});

Using the view, all hook and checking for individual views may not work as intended:

elgg_register_plugin_hook_handler('view', 'all', function($hook, $view_name) {
  // Won't work because "css/elgg" was aliased to "elgg.css"
  if ($view_name == 'css/elgg') {
    // Never executed...
  }

  // Won't work because no canonical views start with css/* anymore
  if (strpos($view_name, 'css/') === 0) {
    // Never executed...
  }
});

Please let us know about any other BC issues this change causes. We’d like to fix as many as possible to make the transition smooth.

`fxp/composer-asset-plugin` is now required to install Elgg from source ¶

We use fxp/composer-asset-plugin to manage our browser assets (js, css, html) with Composer, but it must be installed globally before installing Elgg in order for the bower-asset/* packages to be recognized. To install it, run:

composer global require fxp/composer-asset-plugin

If you don’t do this before running composer install or composer create-project, you will get an error message:

[InvalidArgumentException]
Package fxp/composer-asset-plugin not found

List of deprecated views and view arguments that have been removed ¶

We dropped support for and/or removed the following views:

canvas/layouts/*

categories

categories/view

core/settings/tools

embed/addcontentjs

footer/analytics (Use page/elements/foot instead)

groups/left_column

groups/right_column

groups/search/finishblurb

groups/search/startblurb

input/calendar (Use input/date instead)

input/datepicker (Use input/date instead)

input/pulldown (Use input/select instead)

invitefriends/formitems

js/admin (Use AMD and elgg_require_js instead of extending JS views)

js/initialise_elgg (Use AMD and elgg_require_js instead of extending JS views)

members/nav

metatags (Use the ‘head’, ‘page’ plugin hook instead)

navigation/topbar_tools

navigation/viewtype

notifications/subscriptions/groupsform

object/groupforumtopic

output/calendar (Use output/date instead)

output/confirmlink (Use output/url instead)

page_elements/contentwrapper

page/elements/shortcut_icon (Use the ‘head’, ‘page’ plugin hook instead)

page/elements/wrapper

profile/icon (Use elgg_get_entity_icon)

river/object/groupforumtopic/create

settings/{plugin}/edit (Use plugins/{plugin}/settings instead)

user/search/finishblurb

user/search/startblurb

usersettings/{plugin}/edit (Use plugins/{plugin}/usersettings instead)

widgets/{handler}/view (Use widgets/{handler}/content instead)

We also dropped the following arguments to views:

“value” in output/iframe (Use “src” instead)

“area2” and “area3” in page/elements/sidebar (Use “sidebar” or view extension instead)

“js” in icon views (e.g. icon/user/default)

“options” to input/radio and input/checkboxes which aren’t key-value pairs will no longer be acceptable.

All scripts moved to bottom of page ¶

You should test your plugin with the JavaScript error console visible. For performance reasons, Elgg no longer supports script elements in the head element or in HTML views. elgg_register_js will now load all scripts at the end of the body element.

You must convert inline scripts to AMD or to external scripts loaded with elgg_load_js.

Early in the page, Elgg provides a shim of the RequireJS require() function that simply queues code until the AMD elgg and jQuery modules are defined. This provides a straightforward way to convert many inline scripts to use require().

Inline code which will fail because the stack is not yet loaded:

<script>
$(function () {
    // code using $ and elgg
});
</script>

This should work in Elgg 2.0:

<script>
require(['elgg', 'jquery'], function (elgg, $) {
    $(function () {
        // code using $ and elgg
    });
});
</script>

Attribute formatter removes keys with underscores ¶

elgg_format_attributes() (and all APIs that use it) now filter out attributes whose name contains an underscore. If the attribute begins with data-, however, it will not be removed.

Breadcrumbs ¶

Breadcrumb display now removes the last item if it does not contain a link. To restore the previous behavior, replace the plugin hook handler elgg_prepare_breadcrumbs with your own:

elgg_unregister_plugin_hook_handler('prepare', 'breadcrumbs', 'elgg_prepare_breadcrumbs');
elgg_register_plugin_hook_handler('prepare', 'breadcrumbs', 'myplugin_prepare_breadcrumbs');

function myplugin_prepare_breadcrumbs($hook, $type, $breadcrumbs, $params) {
    // just apply excerpt to titles
    foreach (array_keys($breadcrumbs) as $i) {
        $breadcrumbs[$i]['title'] = elgg_get_excerpt($breadcrumbs[$i]['title'], 100);
    }
    return $breadcrumbs;
}

Callbacks in Queries ¶

Make sure to use only valid callable values for “callback” argument/options in the API.

Querying functions will now will throw a RuntimeException if is_callable() returns false for the given callback value. This includes functions such as elgg_get_entities(), get_data(), and many more.

Comments plugin hook ¶

Plugins can now return an empty string from 'comments',$entity_type hook in order to override the default comments component view. To force the default comments component, your plugin must return false. If you were using empty strings to force the default comments view, you need to update your hook handlers to return false.

Container permissions hook ¶

The behavior of the container_permissions_check hook has changed when an entity is being created: Before 2.0, the hook would be called twice if the entity’s container was not the owner. On the first call, the entity’s owner would be passed in as $params['container'], which could confuse handlers.

In 2.0, when an entity is created in a container like a group, if the owner is the same as the logged in user (almost always the case), this first check is bypassed. So the container_permissions_check hook will almost always be called once with $params['container'] being the correct container of the entity.

Creating or deleting a relationship triggers only one event ¶

The “create” and “delete” relationship events are now only fired once, with "relationship" as the object type.

E.g. Listening for the "create", "member" or "delete", "member" event(s) will no longer capture group membership additions/removals. Use the "create", "relationship" or "delete", "relationship" events.

Discussion feature has been pulled from groups into its own plugin ¶

The object, groupforumtopic subtype has been replaced with the object, discussion subtype. If your plugin is using or altering the old discussion feature, you should upgrade it to use the new subtype.

Nothing changes from the group owners’ point of view. The discussion feature is still available as a group tool and all old discussions are intact.

Elgg has migrated from ext/mysql to PDO MySQL ¶

Elgg now uses a PDO_MYSQL connection and no longer uses any ext/mysql functions. If you use mysql_* functions, implicitly relying on an open connection, these will fail.

If your code uses one of the following functions, read below.

execute_delayed_write_query()
execute_delayed_read_query()

If you provide a callable $handler to be called with the results, your handler will now receive a \Doctrine\DBAL\Driver\Statement object. Formerly this was an ext/mysql result resource.

Event/Hook calling order may change ¶

When registering for events/hooks, the all keyword for wildcard matching no longer has any effect on the order that handlers are called. To ensure your handler is called last, you must give it the highest priority of all matching handlers, or to ensure your handler is called first, you must give it the lowest priority of all matching handlers.

If handlers were registered with the same priority, these are called in the order they were registered.

To emulate prior behavior, Elgg core handlers registered with the all keyword have been raised in priority. Some of these handlers will most likely be called in a different order.

`export/` URLs are no longer available ¶

Elgg no longer provides this endpoint for exposing resource data.

Icons migrated to Font Awesome ¶

Elgg’s sprites and most of the CSS classes beginning with elgg-icon- have been removed.

Usage of elgg_view_icon() is backward compatible, but static HTML using the elgg-icon classes will have to be updated to the new markup.

input/autocomplete view ¶

Plugins that override the input/autocomplete view will need to include the source URL in the data-source attribute of the input element, require the new elgg/autocomplete AMD module, and call its init method. The 1.x javascript library elgg.autocomplete is no longer used.

Introduced third-party library for sending email ¶

We are using the excellent Zend\Mail library to send emails in Elgg 2.0. There are likely edge cases that the library handles differently than Elgg 1.x. Take care to test your email notifications carefully when upgrading to 2.0.

Label elements ¶

The following views received label elements around some of the input fields. If your plugin/theme overrides these views please check for the new content.

views/default/core/river/filter.php
views/default/forms/admin/plugins/filter.php
views/default/forms/admin/plugins/sort.php
views/default/forms/login.php

Plugin Aalborg Theme ¶

The view page/elements/navbar now uses a Font Awesome icon for the mobile menu selector instead of an image. The bars.png image and supporting CSS for the 1.12 rendering has been removed, so update your theme accordingly.

Plugin Likes ¶

Objects are no longer likable by default. To support liking, you can register a handler to permit the annotation, or more simply register for the hook ["likes:is_likable", "<type>:<subtype>"] and return true. E.g.

elgg_register_plugin_hook_handler('likes:is_likable', 'object:mysubtype', 'Elgg\Values::getTrue');

Just as before, the permissions_check:annotate hook is still called and may be used to override default behavior.

Plugin Messages ¶

If you’ve removed or replaced the handler function messages_notifier to hide/alter the inbox icon, you’ll instead need to do the same for the topbar menu handler messages_register_topbar. messages_notifier is no longer used to add the menu link.

Messages will no longer get the metadata ‘msg’ for newly created messages. This means you can not rely on that metadata to exist.

Plugin Blog ¶

The blog pages showing ‘Mine’ or ‘Friends’ listings of blogs have been changed to list all the blogs owned by the users (including those created in groups).

Plugin Bookmarks ¶

The bookmark pages showing ‘Mine’ or ‘Friends’ listings of bookmarks have been changed to list all the bookmarks owned by the users (including those created in groups).

Plugin File ¶

The file pages showing ‘Mine’ or ‘Friends’ listings of files have been changed to list all the files owned by the users (including those created in groups).

Removed Classes ¶

ElggInspector

Notable

FilePluginFile: replace with ElggFile (or load with get_entity())

Removed keys available via `elgg_get_config()`¶

allowed_ajax_views

dataroot_in_settings

externals

externals_map

i18n_loaded_from_cache

language_paths

pagesetupdone

registered_tag_metadata_names

simplecache_enabled_in_settings

translations

viewpath

views

view_path

viewtype

wordblacklist

Also note that plugins should not be accessing the global $CONFIG variable except for in settings.php.

Removed Functions ¶

blog_get_page_content_friends

blog_get_page_content_read

count_unread_messages()

delete_entities()

delete_object_entity()

delete_user_entity()

elgg_get_view_location()

elgg_validate_action_url()

execute_delayed_query()

extend_view()

get_db_error()

get_db_link()

get_entities()

get_entities_from_access_id()

get_entities_from_access_collection()

get_entities_from_annotations()

get_entities_from_metadata()

get_entities_from_metadata_multi()

get_entities_from_relationship()

get_filetype_cloud()

get_library_files()

get_views()

is_ip_in_array()

list_entities()

list_entities_from_annotations()

list_group_search()

list_registered_entities()

list_user_search()

load_plugins()

menu_item()

make_register_object()

mysql_*(): Elgg no longer uses ext/mysql

remove_blacklist()

search_for_group()

search_for_object()

search_for_site()

search_for_user()

search_list_objects_by_name()

search_list_groups_by_name()

search_list_users_by_name()

set_template_handler()

test_ip()

Removed methods ¶

ElggCache::set_variable()

ElggCache::get_variable()

ElggData::initialise_attributes()

ElggData::getObjectOwnerGUID()

ElggDiskFilestore::make_directory_root()

ElggDiskFilestore::make_file_matrix()

ElggDiskFilestore::user_file_matrix()

ElggDiskFilestore::mb_str_split()

ElggEntity::clearMetadata()

ElggEntity::clearRelationships()

ElggEntity::clearAnnotations()

ElggEntity::getOwner()

ElggEntity::setContainer()

ElggEntity::getContainer()

ElggEntity::getIcon()

ElggEntity::setIcon()

ElggExtender::getOwner()

ElggFileCache::create_file()

ElggObject::addToSite(): parent function in ElggEntity still available

ElggObject::getSites(): parent function in ElggEntity still available

ElggSite::getCollections()

ElggUser::addToSite(): parent function in ElggEntity still available

ElggUser::getCollections()

ElggUser::getOwner()

ElggUser::getSites(): parent function in ElggEntity still available

ElggUser::listFriends()

ElggUser::listGroups()

ElggUser::removeFromSite(): parent function in ElggEntity still available

The following arguments have also been dropped:

ElggSite::getMembers() - 2: $offset

elgg_view_entity_list() - 3: $offset - 4: $limit - 5: $full_view - 6: $list_type_toggle - 7: $pagination

Removed Plugin Hooks ¶

[display, view]: See the new plugin hook.

Removed Actions ¶

widgets/upgrade

Removed Views ¶

forms/admin/plugins/change_state

Removed View Variables ¶

During rendering, the view system no longer injects these into the scope:

$vars['url']: replace with elgg_get_site_url()

$vars['user']: replace with elgg_get_logged_in_user_entity()

$vars['config']: use elgg_get_config() and elgg_set_config()

$CONFIG: use elgg_get_config() and elgg_set_config()

Also several workarounds for very old views are no longer performed. Make these changes:

Set $vars['full_view'] instead of $vars['full'].

Set $vars['name'] instead of $vars['internalname'].

Set $vars['id'] instead of $vars['internalid'].

Removed libraries ¶

elgg:markdown: Elgg no longer provides a markdown implementation. You must provide your own.

Specifying View via Properties ¶

The metadata $entity->view no longer specifies the view used to render in elgg_view_entity().

Similarly the property $annotation->view no longer has an effect within elgg_view_annotation().

Viewtype is static after the initial `elgg_get_viewtype()` call ¶

elgg_set_viewtype() must be used to set the viewtype at runtime. Although Elgg still checks the view input and $CONFIG->view initially, this is only done once per request.

Deprecations ¶

It’s deprecated to read or write to metadata keys starting with filestore:: on ElggFile objects. In Elgg 3.0 this metadata will be deleted if it points to the current data root path, so few file objects will have it. Plugins should only use ElggFile::setFilestore if files need to be stored in a custom location.

Note

This is not the only deprecation in Elgg 2.0. Plugin developers should watch their site error logs.

From 1.10 to 1.11 ¶

Comment highlighting ¶

If your theme is using the file views/default/css/elements/components.php, you must add the following style definitions in it to enable highlighting for comments and discussion replies:

.elgg-comments .elgg-state-highlight {
        -webkit-animation: comment-highlight 5s;
        animation: comment-highlight 5s;
}
@-webkit-keyframes comment-highlight {
        from {background: #dff2ff;}
        to {background: white;}
}
@keyframes comment-highlight {
        from {background: #dff2ff;}
        to {background: white;}
}

From 1.9 to 1.10 ¶

File uploads ¶

If your plugin is using a snippet copied from the file/upload action to fix detected mime types for Microsoft zipped formats, it can now be safely removed.

If your upload action performs other manipulations on detected mime and simple types, it is recommended to make use of available plugin hooks:

'mime_type','file' for filtering detected mime types
'simple_type','file' for filtering parsed simple types

From 1.8 to 1.9 ¶

In the examples we are upgrading an imaginary “Photos” plugin.

Only the key changes are included. For example some of the deprecated functions are not mentioned here separately.

Each section will include information whether the change is backwards compatible with Elgg 1.8.

The manifest file ¶

No changes are needed if your plugin is compatible with 1.8.

It’s however recommended to add the <id> tag. It’s value should be the name of the directory where the plugin is located inside the mod/ directory.

If you make changes that break BC, you must update the plugin version and the required Elgg release.

Example of (shortened) old version:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
    <name>Photos</name>
    <author>John Doe</author>
    <version>1.0</version>
    <description>Adds possibility to upload photos and arrange them into albums.</description>
    <requires>
        <type>elgg_release</type>
        <version>1.8</version>
    </requires>
</plugin_manifest>

Example of (shortened) new version:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
    <name>Photos</name>
    <id>photos</id>
    <author>John Doe</author>
    <version>2.0</version>
    <description>Adds possibility to upload photos and arrange them into albums.</description>
    <requires>
        <type>elgg_release</type>
        <version>1.9</version>
    </requires>
</plugin_manifest>

$CONFIG and $vars[‘config’]¶

Both the global $CONFIG variable and the $vars['config'] parameter have been deprecated. They should be replaced with the elgg_get_config() function.

Example of old code:

// Using the global $CONFIG variable:
global $CONFIG;
$plugins_path = $CONFIG->plugins_path

// Using the $vars view parameter:
$plugins_path = $vars['plugins_path'];

Example of new code:

$plugins_path = elgg_get_config('plugins_path');

Note

Compatible with 1.8

Note

See how the community_plugins plugin was updated: https://github.com/Elgg/community_plugins/commit/f233999bbd1478a200ee783679c2e2897c9a0483

Language files ¶

In Elgg 1.8 the language files needed to use the add_translation() function. In 1.9 it is enough to just return the array that was previously passed to the function as a parameter. Elgg core will use the file name (e.g. en.php) to tell which language the file contains.

Example of the old way in languages/en.php:

$english = array(
    'photos:all' => 'All photos',
);
add_translation('en', $english);

Example of new way:

return array(
    'photos:all' => 'All photos',
);

Warning

Not compatible with 1.8

Notifications ¶

One of the biggest changes in Elgg 1.9 is the notifications system. The new system allows more flexible and scalable way of sending notifications.

Example of the old way:

function photos_init() {
    // Tell core that we want to send notifications about new photos
    register_notification_object('object', 'photo', elgg_echo('photo:new'));

    // Register a handler that creates the notification message
    elgg_register_plugin_hook_handler('notify:entity:message', 'object', 'photos_notify_message');
}

/**
 * Set the notification message body
 *
 * @param string $hook    Hook name
 * @param string $type    Hook type
 * @param string $message The current message body
 * @param array  $params  Parameters about the photo
 * @return string
 */
function photos_notify_message($hook, $type, $message, $params) {
    $entity = $params['entity'];
    $to_entity = $params['to_entity'];
    $method = $params['method'];
    if (elgg_instanceof($entity, 'object', 'photo')) {
        $descr = $entity->excerpt;
        $title = $entity->title;
        $owner = $entity->getOwnerEntity();
        return elgg_echo('photos:notification', array(
            $owner->name,
            $title,
            $descr,
            $entity->getURL()
        ));
    }
    return null;
}

Example of the new way:

function photos_init() {
    elgg_register_notification_event('object', 'photo', array('create'));
    elgg_register_plugin_hook_handler('prepare', 'notification:publish:object:photo', 'photos_prepare_notification');
}

/**
 * Prepare a notification message about a new photo
 *
 * @param string                          $hook         Hook name
 * @param string                          $type         Hook type
 * @param Elgg_Notifications_Notification $notification The notification to prepare
 * @param array                           $params       Hook parameters
 * @return Elgg_Notifications_Notification
 */
function photos_prepare_notification($hook, $type, $notification, $params) {
    $entity = $params['event']->getObject();
    $owner = $params['event']->getActor();
    $recipient = $params['recipient'];
    $language = $params['language'];
    $method = $params['method'];

    // Title for the notification
    $notification->subject = elgg_echo('photos:notify:subject', array($entity->title), $language);

    // Message body for the notification
    $notification->body = elgg_echo('photos:notify:body', array(
        $owner->name,
        $entity->title,
        $entity->getExcerpt(),
        $entity->getURL()
    ), $language);

    // The summary text is used e.g. by the site_notifications plugin
    $notification->summary = elgg_echo('photos:notify:summary', array($entity->title), $language);

    return $notification;
}

Warning

Not compatible with 1.8

Note

See how the community_plugins plugin was updated to use the new system: https://github.com/Elgg/community_plugins/commit/bfa356cfe8fb99ebbca4109a1b8a1383b70ff123

Notifications can also be sent with the notify_user() function.

It has however been updated to support three new optional parameters passed inside an array as the fifth parameter.

The parameters give notification plugins more control over the notifications, so they should be included whenever possible. For example the bundled site_notifications plugin won’t work properly if the parameters are missing.

Parameters:

object The object that we are notifying about (e.g. ElggEntity or ElggAnnotation). This is needed so that notification plugins can provide a link to the object.
action String that describes the action that triggered the notification (e.g. “create”, “update”, etc).
summary String that contains a summary of the notification. (It should be more informative than the notification subject but less informative than the notification body.)

Example of the old way:

// Notify $owner that $user has added a $rating to an $entity created by him

$subject = elgg_echo('rating:notify:subject');
$body = elgg_echo('rating:notify:body', array(
        $owner->name,
        $user->name,
        $entity->title,
        $entity->getURL(),
));

notify_user($owner->guid,
                        $user->guid,
                        $subject,
                        $body
                );

Example of the new way:

// Notify $owner that $user has added a $rating to an $entity created by him

$subject = elgg_echo('rating:notify:subject');
$summary = elgg_echo('rating:notify:summary', array($entity->title));
$body = elgg_echo('rating:notify:body', array(
        $owner->name,
        $user->name,
        $entity->title,
        $entity->getURL(),
));

$params = array(
        'object' => $rating,
        'action' => 'create',
        'summary' => $summary,
);

notify_user($owner->guid,
                        $user->guid,
                        $subject,
                        $body,
                        $params
                );

Note

Compatible with 1.8

Adding items to the Activity listing ¶

add_to_river('river/object/photo/create', 'create', $user_guid, $photo_guid);

elgg_create_river_item(array(
    'view' => 'river/object/photo/create',
    'action_type' => 'create',
    'subject_guid' => $user_guid,
    'object_guid' => $photo_guid,
));

You can also add the optional target_guid parameter which tells the target of the create action.

If the photo would had been added for example into a photo album, we could add it by passing in also:

'target_guid' => $album_guid,

Warning

Not compatible with 1.8

Entity URL handlers ¶

The elgg_register_entity_url_handler() function has been deprecated. In 1.9 you should use the 'entity:url', 'object' plugin hook instead.

Example of the old way:

/**
 * Initialize the photo plugin
 */
my_plugin_init() {
    elgg_register_entity_url_handler('object', 'photo', 'photo_url_handler');
}

/**
 * Returns the URL from a photo entity
 *
 * @param ElggEntity $entity
 * @return string
 */
function photo_url_handler($entity) {
    return "photo/view/{$entity->guid}";
}

Example of the new way:

/**
 * Initialize the photo plugin
 */
my_plugin_init() {
    elgg_register_plugin_hook_handler('entity:url', 'object', 'photo_url_handler');
}

/**
 * Returns the URL from a photo entity
 *
 * @param string $hook   'entity:url'
 * @param string $type   'object'
 * @param string $url    The current URL
 * @param array  $params Hook parameters
 * @return string
 */
function photo_url_handler($hook, $type, $url, $params) {
    $entity = $params['entity'];

    // Check that the entity is a photo object
    if ($entity->getSubtype() !== 'photo') {
        // This is not a photo object, so there's no need to go further
        return;
    }

    return "photo/view/{$entity->guid}";
}

Warning

Not compatible with 1.8

Web services ¶

In Elgg 1.8 the web services API was included in core and methods were exposed using expose_function(). To enable the same functionality for Elgg 1.9, enable the “Web services 1.9” plugin and replace all calls to expose_function() with elgg_ws_expose_function().

From 1.7 to 1.8 ¶

Elgg 1.8 is the biggest leap forward in the development of Elgg since version 1.0. As such, there is more work to update core and plugins than with previous upgrades. There were a small number of API changes and following our standard practice, the methods we deprecated have been updated to work with the new API. The biggest changes are in the standardization of plugins and in the views system.

Updating core ¶

Delete the following core directories (same level as _graphics and engine):

_css
account
admin
dashboard
entities
friends
search
settings
simplecache
views

Warning

If you do not delete these directories before an upgrade, you will have problems!

Updating plugins ¶

Use standardized routing with page handlers¶

All: /page_handler/all
User’s content: /page_handler/owner/:username
User’s friends’ content: /page_handler/friends/:username
Single entity: /page_handler/view/:guid/:title
Added: /page_handler/add/:container_guid
Editing: /page_handler/edit/:guid
Group list: /page_handler/group/:guid/all

Include page handler scripts from the page handler¶

Almost every page handler should have a page handler script. (Example: bookmarks/all => mod/bookmarks/pages/bookmarks/all.php)

Call set_input() for entity guids in the page handler and use get_input() in the page handler scripts.
Call gatekeeper() and admin_gatekeeper() in the page handler function if required.
The group URL should use the pages/:handler/owner.php script.
Page handlers should not contain HTML.
Update the URLs throughout the plugin. (Don’t forget to remove /pg/!)

Use standardized page handlers and scripts¶

Store page handler scripts in mod/:plugin/pages/:page_handler/:page_name.php
Use the content page layout in page handler scripts:
```
$content = elgg_view_layout('content', $options);
```
Page handler scripts should not contain HTML.
Call elgg_push_breadcrumb() in the page handler scripts.
No need to set page owner if the URLs are in the standardized format.
For group content, check the container_guid by using elgg_get_page_owner_entity().

The `object/:subtype` view¶

Make sure there are views for $vars['full_view'] == true and $vars['full_view'] == false. $vars['full_view'] replaced $vars['full].
Check for the object in $vars['entity']. Use elgg_instance_of() to make sure it’s the type of entity you want.
Return true to short circuit the view if the entity is missing or wrong.
Use elgg_view(‘object/elements/summary’, array(‘entity’ => $entity)); and elgg_view_menu(‘entity’, array(‘entity’ => $entity)); to help format. You should use very little markup in these views.

Update action structure¶

Namespace action files and action names (example: mod/blog/actions/blog/save.php => action/blog/save)
Use the following action URLs:
- Add: action/:plugin/save
- Edit: action/:plugin/save
- Delete: action/:plugin/delete
Make the delete action accept action/:handler/delete?guid=:guid so the metadata entity menu has the correct URL by default.

Update deprecated functions¶

Functions deprecated in 1.7 will produce visible errors in 1.8.
You can also update functions deprecated in 1.8.
- Many registration functions simply added an elgg_ prefix for consistency, and should be easy to update.
- See /engine/lib/deprecated-1.8.php for the full list.
- You can set the debug level to “warning” to get visual reminders of deprecated functions.

Update the group profile module¶

Use the blog or file plugins for examples. This will help with making your plugin themeable by the new CSS framework.

Update forms¶

Move form bodies to the forms/:action view to use Evan’s new elgg_view_form.
Use input views in form bodies rather than html. This helps with theming and future-proofing.
Add a function that prepares the form (see mod/file/lib/file.php for an example)
Make your forms sticky (see the file plugin’s upload action and form prepare function).

The forms API is discussed in more detail in Forms + Actions.

Clean up CSS/HTML¶

We have added many CSS patterns to the base CSS file (modules, image block, spacing primitives). We encourage you to use these patterns and classes wherever possible. Doing so should:

Reduce maintenance costs, since you can delete most custom CSS.
Make your plugin more compatible with community themes.

Look for patterns that can be moved into core if you need significant CSS.

We use hyphens rather than underscores in classes/ids and encourage you do the same for consistency.

If you do need your own CSS, you should use your own namespace, rather than elgg-.

Update manifest.xml¶

Use http://el.gg/manifest17to18 to automate this.
Don’t use the “bundled” category with your plugins. That is only for plugins distributed with Elgg.

Update settings and user settings views¶

The view for settings is now plugins/:plugin/settings (previously settings/:plugin/edit).
The view for user settings is now plugins/:plugin/usersettings (previously usersettings/:plugin/edit).

List of events in core¶

Contents

System events
User events
Relationship events
Entity events
Metadata events
Annotation events
River events
File events
Notes

System events ¶

boot, system: First event triggered. Triggered before plugins have been loaded.
plugins_boot, system: Triggered just after the plugins are loaded. Rarely used. init, system is used instead.
init, system: Plugins tend to use this event for initialization (extending views, registering callbacks, etc.)
ready, system: Triggered after the init, system event. All plugins are fully loaded and the engine is ready to serve pages.
pagesetup, system (deprecated in 2.3): Called just before the first content is produced. Is triggered by elgg_view(). Use the menu or page shell hooks instead.
shutdown, system: Triggered after the page has been sent to the user. Expensive operations could be done here and not make the user wait.

Note

Depending upon your server configuration the PHP output might not be shown until after the process is completed. This means that any long-running processes will still delay the page load.

Note

This event is prefered above using register_shutdown_function as you may not have access to all the Elgg services (eg. database) in the shutdown function but you will in the event.

regenerate_site_secret:before, system

Return false to cancel regenerating the site secret. You should also provide a message to the user.

regenerate_site_secret:after, system

Triggered after the site secret has been regenerated.

log, systemlog

Called for all triggered events. Used internally by system_log_default_logger() to populate the system_log table.

upgrade, system

Triggered after a system upgrade has finished. All upgrade scripts have run, but the caches are not cleared.

upgrade, upgrade

A single upgrade script finished executing. Handlers are passed a stdClass object with the properties

from - The version of Elgg upgrading from.
to - The version just upgraded to.

activate, plugin

Return false to prevent activation of the plugin.

deactivate, plugin

Return false to prevent deactivation of the plugin.

init:cookie, <name>

Return false to override setting a cookie.

cache:flush, system

Reset internal and external caches, by default including system_cache, simplecache, and memcache. One might use it to reset others such as APC, OPCache, or WinCache.

send:before, http_response

Triggered before an HTTP response is sent. Handlers will receive an instance of SymfonyComponentHttpFoundationResponse that is to be sent to the requester. Handlers can terminate the event and prevent the response from being sent by returning false.

send:after, http_response

Triggered after an HTTP response is sent. Handlers will receive an instance of SymfonyComponentHttpFoundationResponse that was sent to the requester.

User events ¶

login:before, user: Triggered during login. Returning false prevents the user from logging
login:after, user: Triggered after the user logs in.
logout:before, user: Triggered during logout. Returning false should prevent the user from logging out.
logout:after, user: Triggered after the user logouts.
validate, user: When a user registers, the user’s account is disabled. This event is triggered to allow a plugin to determine how the user should be validated (for example, through an email with a validation link).
profileupdate, user: User has changed profile
profileiconupdate, user: User has changed profile icon
ban, user: Triggered before a user is banned. Return false to prevent.
unban, user: Triggered before a user is unbanned. Return false to prevent.
make_admin, user: Triggered before a user is promoted to an admin. Return false to prevent.
remove_admin, user: Triggered before a user is demoted from an admin. Return false to prevent.

Relationship events ¶

create, relationship: Triggered after a relationship has been created. Returning false deletes the relationship that was just created.

Note

This event was broken in Elgg 1.9 - 1.12.3, returning false would not delete the relationship. This is working as of 1.12.4

delete, relationship: Triggered before a relationship is deleted. Return false to prevent it from being deleted.
join, group: Triggered after the user $params['user'] has joined the group $params['group'].
leave, group: Triggered before the user $params['user'] has left the group $params['group'].

Entity events ¶

create, <entity type>: Triggered for user, group, object, and site entities after creation. Return false to delete entity.
update, <entity type>: Triggered before an update for the user, group, object, and site entities. Return false to prevent update. The entity method getOriginalAttributes() can be used to identify which attributes have changed since the entity was last saved.
update:after, <entity type>: Triggered after an update for the user, group, object, and site entities. The entity method getOriginalAttributes() can be used to identify which attributes have changed since the entity was last saved.
delete, <entity type>: Triggered before entity deletion. Return false to prevent deletion.
disable, <entity type>: Triggered before the entity is disabled. Return false to prevent disabling.
disable:after, <entity type>: Triggered after the entity is disabled.
enable, <entity type>: Return false to prevent enabling.
enable:after, <entity type>: Triggered after the entity is enabled.

Metadata events ¶

create, metadata: Called after the metadata has been created. Return false to delete the metadata that was just created.
update, metadata: Called after the metadata has been updated. Return false to delete the metadata.
delete, metadata: Called before metadata is deleted. Return false to prevent deletion.
enable, metadata: Called when enabling metadata. Return false to prevent enabling.
disable, metadata: Called when disabling metadata. Return false to prevent disabling.

Annotation events ¶

annotate, <entity type>: Called before the annotation has been created. Return false to prevent annotation of this entity.
create, annotation: Called after the annotation has been created. Return false to delete the annotation.
update, annotation: Called after the annotation has been updated. Return false to delete the annotation.
delete, annotation: Called before annotation is deleted. Return false to prevent deletion.
enable, annotation: Called when enabling annotations. Return false to prevent enabling.
disable, annotations: Called when disabling annotations. Return false to prevent disabling.

River events ¶

created, river: Called after a river item is created.

Note

Use the plugin hook creating, river to cancel creation (or alter options).
delete:before, river: Triggered before a river item is deleted. Returning false cancels the deletion.
delete:after, river: Triggered after a river item was deleted.

File events ¶

upload:after, file: Called after an uploaded file has been written to filestore. Receives an instance of ElggFile the uploaded file was written to. The ElggFile may or may not be an entity with a GUID.

Notes ¶

Because of bugs in the Elgg core, some events may be thrown more than once on the same action. For example, update, object is thrown twice.

List of plugin hooks in core¶

Contents

System hooks
User hooks
Object hooks
Action hooks
Ajax
Permission hooks
Notifications
Routing
Views
Files
Other
Plugins

System hooks ¶

page_owner, system: Filter the page_owner for the current page. No options are passed.

siteid, system

gc, system: Allows plugins to run garbage collection for $params['period'].
unit_test, system: Add a Simple Test test. (Deprecated.)
diagnostics:report, system: Filter the output for the diagnostics report download.

search_types, get_types

cron, <period>

Triggered by cron for each period.

validate, input

Filter GET and POST input. This is used by get_input() to sanitize user input.

geocode, location

Deprecated as of 1.9.

diagnostics:report, system

Filters the output for a diagnostic report.

debug, log

Triggered by the Logger. Return false to stop the default logging method. $params includes:

level - The debug level. One of:
- Elgg_Logger::OFF
- Elgg_Logger::ERROR
- Elgg_Logger::WARNING
- Elgg_Logger::NOTICE
- Elgg_Logger::INFO
msg - The message
display - Should this message be displayed?

format, friendly:title

Formats the “friendly” title for strings. This is used for generating URLs.

format, friendly:time

Formats the “friendly” time for the timestamp $params['time'].

format, strip_tags

Filters a string to remove tags. The original string is passed as $params['original_string'] and an optional set of allowed tags is passed as $params['allowed_tags'].

output:before, page

In elgg_view_page(), this filters $vars before it’s passed to the page shell view (page/<page_shell>). To stop sending the X-Frame-Options header, unregister the handler _elgg_views_send_header_x_frame_options() from this hook.

output, page

In elgg_view_page(), this filters the output return value.

output:before, layout

In elgg_view_layout(), filters $params before it’s passed to the layout view.

output:after, layout

In elgg_view_layout(), filters the return value of the layout view.

parameters, menu:<menu_name>

Triggered by elgg_view_menu(). Used to change menu variables (like sort order) before rendering.

register, menu:<menu_name>

Filters the initial list of menu items pulled from configuration, before the menu has been split into sections. Triggered by elgg_view_menu() and elgg()->menus->getMenu().

prepare, menu:<menu_name>

Filters the array of menu sections before they’re displayed. Each section is a string key mapping to an area of menu items. This is a good hook to sort, add, remove, and modify menu items. Triggered by elgg_view_menu() and elgg()->menus->prepareMenu().

creating, river

The options for elgg_create_river_item are filtered through this hook. You may alter values or return false to cancel the item creation.

simplecache:generate, <view>

Triggered when generating the cached content of a view.

prepare, breadcrumbs

In elgg_get_breadcrumbs(), this filters the registered breadcrumbs before returning them, allowing a plugin to alter breadcrumb strategy site-wide.

add, river

elgg.data, site: Filters cached configuration data to pass to the client. More info
elgg.data, page: Filters uncached, page-specific configuration data to pass to the client. More info
registration_url, site: Filters site’s registration URL. Can be used by plugins to attach invitation codes, referrer codes etc. to the registration URL. $params array contains an array of query elements added to the registration URL by the invoking script. The hook must return an absolute URL to the registration page.
login_url, site: Filters site’s login URL. $params array contains an array of query elements added to the login URL by the invoking script. The hook must return an absolute URL of the login page.

User hooks ¶

usersettings:save, user: Triggered in the aggregate action to save user settings. Return false prevent sticky forms from being cleared.
access:collections:write, user: Filters an array of access permissions that the user $params['user_id'] is allowed to save content with. Permissions returned are of the form (id => ‘Human Readable Name’).
registeruser:validate:username, all: Return boolean for if the string in $params['username'] is valid for a username.
registeruser:validate:password, all: Return boolean for if the string in $params['password'] is valid for a password.
registeruser:validate:email, all: Return boolean for if the string in $params['email'] is valid for an email address.
register, user: Triggered by the register action after the user registers. Return false to delete the user. Note the function register_user does not trigger this hook.
login:forward, user: Filters the URL to which the user will be forwarded after login.
find_active_users, system: Return the number of active users.
status, user: Triggered by The Wire when adding a post.
username:character_blacklist, user: Filters the string of blacklisted characters used to validate username during registration. The return value should be a string consisting of the disallowed characters. The default string can be found from $params['blacklist'].

Object hooks ¶

comments, <entity_type>: Triggered in elgg_view_comments(). If returning content, this overrides the page/elements/comments view.
comments:count, <entity_type>: Return the number of comments on $params['entity'].
likes:count, <entity_type>: Return the number of likes for $params['entity'].

Action hooks ¶

action, <action>: Triggered before executing action scripts. Return false to abort action.
action_gatekeeper:permissions:check, all: Triggered after a CSRF token is validated. Return false to prevent validation.
action_gatekeeper:upload_exceeded_msg, all: Triggered when a POST exceeds the max size allowed by the server. Return an error message to display.
forward, <reason>: Filter the URL to forward a user to when forward($url, $reason) is called.
response, action:<action>: Filter an instance of \Elgg\Http\ResponseBuilder before it is sent to the client. This hook can be used to modify response content, status code, forward URL, or set additional response headers. Note that the <action> value is parsed from the request URL, therefore you may not be able to filter the responses of action() calls if they are nested within the another action script file.

Ajax ¶

ajax_response, *

When the elgg/Ajax AMD module is used, this hook gives access to the response object (\Elgg\Services\AjaxResponse) so it can be altered/extended. The hook type depends on the method call:

elgg/Ajax method	plugin hook type
action()	action:<action_name>
path()	path:<url_path>
view()	view:<view_name>
form()	form:<action_name>

output, ajax

This filters the JSON output wrapper returned to the legacy ajax API (elgg.ajax, elgg.action, etc.). Plugins can alter the output, forward URL, system messages, and errors. For the elgg/Ajax AMD module, use the ajax_response hook documented above.

Permission hooks ¶

container_logic_check, <entity_type>

Triggered by ElggEntity:canWriteToContainer() before triggering permissions_check and container_permissions_check hooks. Unlike permissions hooks, logic check can be used to prevent certain entity types from being contained by other entity types, e.g. discussion replies should only be contained by discussions. This hook can also be used to apply status logic, e.g. do disallow new replies for closed discussions.

The handler should return false to prevent an entity from containing another entity. The default value passed to the hook is null, so the handler can check if another hook has modified the value by checking if return value is set. Should this hook return false, container_permissions_check and permissions_check hooks will not be triggered.

The $params array will contain:

container - An entity that will be used as a container

user - User who will own the entity to be written to container

subtype - Subtype of the entity to be written to container (entity type is assumed from hook type)

container_permissions_check, <entity_type>

Return boolean for if the user $params['user'] can use the entity $params['container'] as a container for an entity of <entity_type> and subtype $params['subtype'].

In the rare case where an entity is created with neither the container_guid nor the owner_guid matching the logged in user, this hook is called twice, and in the first call $params['container'] will be the owner, not the entity’s real container.

The $params array will contain:

container - An entity that will be used as a container

user - User who will own the entity to be written to container

subtype - Subtype of the entity to be written to container (entity type is assumed from hook type)

permissions_check, <entity_type>

Return boolean for if the user $params['user'] can edit the entity $params['entity'].

permissions_check:delete, <entity_type>

Return boolean for if the user $params['user'] can delete the entity $params['entity']. Defaults to $entity->canEdit().

permissions_check:delete, river

Return boolean for if the user $params['user'] can delete the river item $params['item']. Defaults to true for admins and false for other users.

Note

This check is not performed when using the deprecated elgg_delete_river().

permissions_check, widget_layout

Return boolean for if $params['user'] can edit the widgets in the context passed as $params['context'] and with a page owner of $params['page_owner'].

permissions_check:metadata, <entity_type>

Return boolean for if the user $params['user'] can edit the metadata $params['metadata'] on the entity $params['entity'].

permissions_check:comment, <entity_type>

Return boolean for if the user $params['user'] can comment on the entity $params['entity'].

permissions_check:annotate:<annotation_name>, <entity_type>

Return boolean for if the user $params['user'] can create an annotation <annotation_name> on the entity $params['entity']. If logged in, the default is true.

Note

This is called before the more general permissions_check:annotate hook, and its return value is that hook’s initial value.

permissions_check:annotate, <entity_type>

Return boolean for if the user $params['user'] can create an annotation $params['annotation_name'] on the entity $params['entity']. if logged in, the default is true.

Warning

This is functions differently than the permissions_check:metadata hook by passing the annotation name instead of the metadata object.

permissions_check:annotation

Return boolean for if the user in $params['user'] can edit the annotation $params['annotation'] on the entity $params['entity']. The user can be null.

fail, auth

Return the failure message if authentication failed. An array of previous PAM failure methods is passed as $params.

api_key, use

Triggered by api_auth_key(). Returning false prevents the key from being authenticated.

access:collections:read, user

Filters an array of access IDs that the user $params['user_id'] can see.

Warning

The handler needs to either not use parts of the API that use the access system (triggering the hook again) or to ignore the second call. Otherwise, an infinite loop will be created.

access:collections:write, user

Filters an array of access IDs that the user $params['user_id'] can write to. In get_write_access_array(), this hook filters the return value, so it can be used to alter the available options in the input/access view. For core plugins, the value “input_params” has the keys “entity” (ElggEntity|false), “entity_type” (string), “entity_subtype” (string), “container_guid” (int) are provided. An empty entity value generally means the form is to create a new object.

Warning

The handler needs to either not use parts of the API that use the access system (triggering the hook again) or to ignore the second call. Otherwise, an infinite loop will be created.

access:collections:addcollection, collection

Triggered after an access collection $params['collection_id'] is created.

access:collections:deletecollection, collection

Triggered before an access collection $params['collection_id'] is deleted. Return false to prevent deletion.

access:collections:add_user, collection

Triggered before adding user $params['user_id'] to collection $params['collection_id']. Return false to prevent adding.

access:collections:remove_user, collection

Triggered before removing user $params['user_id'] to collection $params['collection_id']. Return false to prevent removal.

get_sql, access

Filters the SQL clauses used in _elgg_get_access_where_sql().

gatekeeper, <entity_type>:<entity_subtype>

Filters the result of elgg_entity_gatekeeper() to prevent access to an entity that user would otherwise have access to. A handler should return false to deny access to an entity.

Notifications ¶

These hooks are listed chronologically in the lifetime of the notification event. Note that not all hooks apply to instant notifications.

enqueue, notification

Can be used to prevent a notification event from sending subscription notifications. Hook handler must return false to prevent a subscription notification event from being enqueued.

$params array includes:

object - object of the notification event

action - action that triggered the notification event. E.g. corresponds to publish when elgg_trigger_event('publish', 'object', $object) is called

get, subscriptions

Filters subscribers of the notification event. Applies to subscriptions and instant notifications. In case of a subscription event, by default, the subscribers list consists of the users subscribed to the container entity of the event object. In case of an instant notification event, the subscribers list consists of the users passed as recipients to notify_user()

$params array includes:

event - \Elgg\Notifications\NotificationEvent instance that describes the notification event

origin - subscriptions_service or instant_notifications

methods_override - delivery method preference for instant notifications

Handlers must return an array in the form:

array(
        <user guid> => array('sms'),
        <user_guid2> => array('email', 'sms', 'ajax')
);

send:before, notifications

Triggered before the notification event queue is processed. Can be used to terminate the notification event. Applies to subscriptions and instant notifications.

$params array includes:

event - \Elgg\Notifications\NotificationEvent instance that describes the notification event

subscriptions - a list of subscriptions. See 'get', 'subscriptions' hook for details

prepare, notification

A high level hook that can be used to alter an instance of \Elgg\Notifications\Notification before it is sent to the user. Applies to subscriptions and instant notifications. This hook is triggered before a more granular 'prepare', 'notification:<action>:<entity_type>:<entity_subtype>' and after 'send:before', 'notifications. Hook handler should return an altered notification object.

$params may vary based on the notification type and may include:

event - \Elgg\Notifications\NotificationEvent instance that describes the notification event

object - object of the notification event. Can be null for instant notifications

action - action that triggered the notification event. May default to notify_user for instant notifications

method - delivery method (e.g. email, site)

sender - sender

recipient - recipient

language - language of the notification (recipient’s language)

origin - subscriptions_service or instant_notifications

prepare, notification:<action>:<entity_type>:<entity_type>

A granular hook that can be used to filter a notification \Elgg\Notifications\Notification before it is sent to the user. Applies to subscriptions and instant notifications. In case of instant notifications that have not received an object, the hook will be called as 'prepare', 'notification:<action>'. In case of instant notifications that have not received an action name, it will default to notify_user.

$params include:

event - \Elgg\Notifications\NotificationEvent instance that describes the notification event

object - object of the notification event. Can be null for instant notifications

action - action that triggered the notification event. May default to notify_user for instant notifications

method - delivery method (e.g. email, site)

sender - sender

recipient - recipient

language - language of the notification (recipient’s language)

origin - subscriptions_service or instant_notifications

format, notification:<method>

This hook can be used to format a notification before it is passed to the 'send', 'notification:<method>' hook. Applies to subscriptions and instant notifications. The hook handler should return an instance of \Elgg\Notifications\Notification. The hook does not receive any $params. Some of the use cases include:

Strip tags from notification title and body for plaintext email notifications

Inline HTML styles for HTML email notifications

Wrap notification in a template, add signature etc.

send, notification:<method>

Delivers a notification. Applies to subscriptions and instant notifications. The handler must return true or false indicating the success of the delivery.

$params array includes:

notification - a notification object \Elgg\Notifications\Notification

email, system

Triggered by elgg_send_email(). Applies to subscriptions and instant notifications with email method. This hook can be used to alter email parameters (subject, body, headers etc) - the handler should return an array of altered parameters. This hook can also be used to implement a custom email transport (in place of Elgg’s default plaintext \Zend\Mail\Transport\Sendmail) - the handler must return true or false to indicate whether the email was sent using a custom transport.

$params contains:

to - email address or string in the form Name <name@example.org> of the recipient

from - email address or string in the form Name <name@example.org> of the sender

subject - subject line of the email

body - body of the email

headers - an array of headers

params - other parameters inherited from the notification object or passed directly to elgg_send_email()

send:after, notifications

Triggered after all notifications in the queue for the notifications event have been processed. Applies to subscriptions and instant notifications.

$params array includes:

event - \Elgg\Notifications\NotificationEvent instance that describes the notification event

subscriptions - a list of subscriptions. See 'get', 'subscriptions' hook for details

deliveries - a matrix of delivery statuses by user for each delivery method

Routing ¶

route, <identifier>: Allows applying logic or returning a response before the page handler is called. See Routing for details. Note that plugins using this hook to rewrite paths, will not be able to filter the response object by its final path and should either switch to route:rewrite, <identifier> hook or use response, path:<path> hook for the original path.
route:rewrite, <identifier>: Allows altering the site-relative URL path. See Routing for details.
response, path:<path>: Filter an instance of \Elgg\Http\ResponseBuilder before it is sent to the client. This hook type will only be used if the path did not start with “action/” or “ajax/”. This hook can be used to modify response content, status code, forward URL, or set additional response headers. Note that the <path> value is parsed from the request URL, therefore plugins using the route hook should use the original <path> to filter the response, or switch to using the route:rewrite hook.
ajax_response, path:<path>: Filters ajax responses before they’re sent back to the elgg/Ajax module. This hook type will only be used if the path did not start with “action/” or “ajax/”.

Views ¶

view_vars, <view_name>: Filters the $vars array passed to the view
view, <view_name>: Filters the returned content of the view
layout, page: In elgg_view_layout(), filters the layout name
shell, page: In elgg_view_page(), filters the page shell name
head, page: In elgg_view_page(), filters $vars['head'] Return value contains an array with title, metas and links keys, where metas is an array of elements to be formatted as <meta> head tags, and links is an array of elements to be formatted as <link> head tags. Each meta and link element contains a set of key/value pairs that are formatted into html tag attributes, e.g.

return [
   'title' => 'Current page title',
   'metas' => [
      'viewport' => [
         'name' => 'viewport',
         'content' => 'width=device-width',
          ]
   ],
   'links' => [
      'rss' => [
         'rel' => 'alternative',
         'type' => 'application/rss+xml',
         'title' => 'RSS',
         'href' => elgg_format_url($url),
      ],
      'icon-16' => [
         'rel' => 'icon',
         'sizes' => '16x16',
         'type' => 'image/png',
                 'href' => elgg_get_simplecache_url('favicon-16.png'),
      ],
   ],
];

ajax_response, view:<view>: Filters ajax/view/ responses before they’re sent back to the elgg/Ajax module.
ajax_response, form:<action>: Filters ajax/form/ responses before they’re sent back to the elgg/Ajax module.
response, view:<view_name>: Filter an instance of \Elgg\Http\ResponseBuilder before it is sent to the client. Applies to request to /ajax/view/<view_name>. This hook can be used to modify response content, status code, forward URL, or set additional response headers.
response, form:<form_name>: Filter an instance of \Elgg\Http\ResponseBuilder before it is sent to the client. Applies to request to /ajax/form/<form_name>. This hook can be used to modify response content, status code, forward URL, or set additional response headers.
table_columns:call, <name>: When the method elgg()->table_columns->$name() is called, this hook is called to allow plugins to override or provide an implementation. Handlers receive the method arguments via $params['arguments'] and should return an instance of Elgg\Views\TableColumn if they wish to specify the column directly.

Files ¶

mime_type, file

Return the mimetype for the filename $params['filename'] with original filename $params['original_filename'] and with the default detected mimetype of $params['default'].

simple_type, file

In elgg_get_file_simple_type(), filters the return value. The hook uses $params['mime_type'] (e.g. application/pdf or image/jpeg) and determines an overall category like document or image. The bundled file plugin and other-third party plugins usually store simpletype metadata on file entities and make use of it when serving icons and constructing ege* filters and menus.

upload, file

Allows plugins to implement custom logic for moving an uploaded file into an instance of ElggFile. The handler must return true to indicate that the uploaded file was moved. The handler must return false to indicate that the uploaded file could not be moved. Other returns will indicate that ElggFile::acceptUploadedFile should proceed with the default upload logic.

$params array includes:

file - instance of ElggFile to write to

upload - instance of Symfony’s UploadedFile

Other ¶

config, comments_per_page

Filters the number of comments displayed per page. Default is 25.

default, access

In get_default_access(), this hook filters the return value, so it can be used to alter the default value in the input/access view. For core plugins, the value “input_params” has the keys “entity” (ElggEntity|false), “entity_type” (string), “entity_subtype” (string), “container_guid” (int) are provided. An empty entity value generally means the form is to create a new object.

entity:icon:sizes, <entity_type>

Triggered by elgg_get_icon_sizes() and sets entity type/subtype specific icon sizes. entity_subtype will be passed with the $params array to the callback.

entity:<icon_type>:sizes, <entity_type>

Allows filtering sizes for custom icon types, see entity:icon:sizes, <entity_type>.

The hook must return an associative array where keys are the names of the icon sizes (e.g. “large”), and the values are arrays with the following keys:

w - Width of the image in pixels

h - Height of the image in pixels

square - Should the aspect ratio be a square (true/false)

upscale - Should the image be upscaled in case it is smaller than the given width and height (true/false)

If the configuration array for an image size is empty, the image will be saved as an exact copy of the source without resizing or cropping.

Example:

return [
        'small' => [
                'w' => 60,
                'h' => 60,
                'square' => true,
                'upscale' => true,
        ],
        'large' => [
                'w' => 600,
                'h' => 600,
                'upscale' => false,
        ],
        'original' => [],
];

entity:icon:url, <entity_type>

Triggered when entity icon URL is requested, see entity icons. Callback should return URL for the icon of size $params['size'] for the entity $params['entity']. Following parameters are available through the $params array:

entity: Entity for which icon url is requested.
viewtype: The type of view e.g. 'default' or 'json'.
size: Size requested, see entity icons for possible values.

Example on how one could default to a Gravatar icon for users that have not yet uploaded an avatar:

// Priority 600 so that handler is triggered after avatar handler
elgg_register_plugin_hook_handler('entity:icon:url', 'user', 'gravatar_icon_handler', 600);

/**
 * Default to icon from gravatar for users without avatar.
 */
function gravatar_icon_handler($hook, $type, $url, $params) {
        // Allow users to upload avatars
        if ($params['entity']->icontime) {
                return $url;
        }

        // Generate gravatar hash for user email
        $hash = md5(strtolower(trim($params['entity']->email)));

        // Default icon size
        $size = '150x150';

        // Use configured size if possible
        $config = elgg_get_icon_sizes('user');
        $key = $params['size'];
        if (isset($config[$key])) {
                $size = $config[$key]['w'] . 'x' . $config[$key]['h'];
        }

        // Produce URL used to retrieve icon
        return "http://www.gravatar.com/avatar/$hash?s=$size";
}

entity:<icon_type>:url, <entity_type>

Allows filtering URLs for custom icon types, see entity:icon:url, <entity_type>

entity:icon:file, <entity_type>

Triggered by ElggEntity::getIcon() and allows plugins to provide an alternative ElggIcon object that points to a custom location of the icon on filestore. The handler must return an instance of ElggIcon or an exception will be thrown.

entity:<icon_type>:file, <entity_type>

Allows filtering icon file object for custom icon types, see entity:icon:file, <entity_type>

entity:<icon_type>:prepare, <entity_type>

Triggered by ElggEntity::saveIcon*() methods and can be used to prepare an image from uploaded/linked file. This hook can be used to e.g. rotate the image before it is resized/cropped, or it can be used to extract an image frame if the uploaded file is a video. The handler must return an instance of ElggFile with a simpletype that resolves to image. The $return value passed to the hook is an instance of ElggFile that points to a temporary copy of the uploaded/linked file.

The $params array contains:

entity - entity that owns the icons

file - original input file before it has been modified by other hooks

entity:<icon_type>:save, <entity_type>

Triggered by ElggEntity::saveIcon*() methods and can be used to apply custom image manipulation logic to resizing/cropping icons. The handler must return true to prevent the core APIs from resizing/cropping icons. The $params array contains:

entity - entity that owns the icons

file - ElggFile object that points to the image file to be used as source for icons

x1, y1, x2, y2 - cropping coordinates

entity:<icon_type>:saved, <entity_type>

Triggered by ElggEntity::saveIcon*() methods once icons have been created. This hook can be used by plugins to create river items, update cropping coordinates for custom icon types etc. The handler can access the created icons using ElggEntity::getIcon(). The $params array contains:

entity - entity that owns the icons

x1, y1, x2, y2 - cropping coordinates

entity:<icon_type>:delete, <entity_type>

Triggered by ElggEntity::deleteIcon() method and can be used for clean up operations. This hook is triggered before the icons are deleted. The handler can return false to prevent icons from being deleted. The $params array contains:

entity - entity that owns the icons

entity:url, <entity_type>

Return the URL for the entity $params['entity']. Note: Generally it is better to override the getUrl() method of ElggEntity. This hook should be used when it’s not possible to subclass (like if you want to extend a bundled plugin without overriding many views).

to:object, <entity_type|metadata|annotation|relationship|river_item>

Converts the entity $params['entity'] to a StdClass object. This is used mostly for exporting entity properties for portable data formats like JSON and XML.

extender:url, <annotation|metadata>

Return the URL for the annotation or metadatum $params['extender'].

file:icon:url, override

Override a file icon URL.

is_member, group

Return boolean for if the user $params['user'] is a member of the group $params['group'].

entity:annotate, <entity_type>

Triggered in elgg_view_entity_annotations(), which is called by elgg_view_entity(). Can be used to add annotations to all full entity views.

usersetting, plugin

Filter user settings for plugins. $params contains:

user - An ElggUser instance
plugin - An ElggPlugin instance
plugin_id - The plugin ID
name - The name of the setting
value - The value to set

setting, plugin

Filter plugin settings. $params contains:

plugin - An ElggPlugin instance
plugin_id - The plugin ID
name - The name of the setting
value - The value to set

relationship:url, <relationship_name>

Filter the URL for the relationship object $params['relationship'].

profile:fields, group

Filter an array of profile fields. The result should be returned as an array in the format name => input view name. For example:

array(
        'about' => 'longtext'
);

profile:fields, profile: Filter an array of profile fields. The result should be returned as an array in the format name => input view name. For example:

array(
        'about' => 'longtext'
);

widget_settings, <widget_handler>: Triggered when saving a widget settings $params['params'] for widget $params['widget']. If handling saving the settings, the handler should return true to prevent the default code from running.
handlers, widgets: Triggered when a list of available widgets is needed. Plugins can conditionally add or remove widgets from this list or modify attributes of existing widgets like context or multiple.
get_list, default_widgets: Filters a list of default widgets to add for newly registered users. The list is an array of arrays in the format:

array(
        'event' => $event,
        'entity_type' => $entity_type,
        'entity_subtype' => $entity_subtype,
        'widget_context' => $widget_context
)

public_pages, walled_garden

Filter the URLs that are can be seen by logged out users if Walled Garden is enabled. $value is an array of regex strings that will allow access if matched.

volatile, metadata

Triggered when exporting an entity through the export handler. This is rare. This allows handler to handle any volatile (non-persisted) metadata on the entity. It’s preferred to use the to:object, <type> hook.

maintenance:allow, url

Return boolean if the URL $params['current_url'] and the path $params['current_path']: is allowed during maintenance mode.

robots.txt, site

Filter the robots.txt values for $params['site'].

config, amd

Filter the AMD config for the requirejs library.

Plugins ¶

Embed¶

embed_get_items, <active_section>

embed_get_sections, all

embed_get_upload_sections, all

Groups¶

profile_buttons, group: Filters buttons (ElggMenuItem instances) to be registered in the title menu of the group profile page
tool_options, group: Use this hook to influence the available group tool options

HTMLawed¶

allowed_styles, htmlawed: Filter the HTMLawed allowed style array.
config, htmlawed: Filter the HTMLawed config array.

Likes¶

likes:is_likable, <type>:<subtype>: This is called to set the default permissions for whether to display/allow likes on an entity of type <type> and subtype <subtype>.

Note

The callback 'Elgg\Values::getTrue' is a useful handler for this hook.

Members¶

members:list, <page_segment>: To handle the page /members/$page_segment, register for this hook and return the HTML of the list.
members:config, tabs: This hook is used to assemble an array of tabs to be passed to the navigation/tabs view for the members pages.

Twitter API¶

authorize, twitter_api: Triggered when a user is authorizes Twitter for a login. $params['token'] contains the Twitter authorization token.

Reported Content¶

reportedcontent:add, system: Triggered after adding the reported content object $params['report']. Return false to delete report.
reportedcontent:archive, system: Triggered before archiving the reported content object $params['report']. Return false to prevent archiving.
reportedcontent:delete, system: Triggered before deleting the reported content object $params['report']. Return false to prevent deleting.

Search¶

search, <type>:<subtype>: Filter more granular search results than searching by type alone. Must return an array with count as the total count of results and entities an array of ElggUser entities.

search, tags

search, <type>: Filter the search for entities for type $type. Must return an array with count as the total count of results and entities an array of ElggUser entities.
search_types, get_types: Filter an array of search types. This allows plugins to add custom types that don’t correspond directly to entities.
search_types, get_queries: Before a search this filters the types queried. This can be used to reorder the display of search results.

Web Services¶

rest, init: Triggered by the web services rest handler. Plugins can set up their own authentication handlers, then return true to prevent the default handlers from being registered.
rest:output, <method_name>: Filter the result (and subsequently the output) of the API method

Tutorials¶

Walk through all the required steps in order to customize Elgg.

The instructions are detailed enough that you don’t need much previous experience with Elgg.

Hello world¶

This tutorial shows you how to create a new plugin that consists of a new page with the text “Hello world” on it.

Before anything else, you need to install Elgg.

In this tutorial we will pretend your site’s URL is https://elgg.example.com.

First, create a directory that will contain the plugin’s files. It should be located under the mod/ directory which is located in your Elgg installation directory. So in this case, create mod/hello/.

Manifest file¶

Elgg requires that your plugin has a manifest file that contains information about the plugin. Therefore, in the directory you just created, create a file called manifest.xml and copy this code into it:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
    <name>Hello world</name>
    <id>hello</id>
    <author>Your Name Here</author>
    <version>0.1</version>
    <description>Hello world, testing.</description>
    <requires>
        <type>elgg_release</type>
        <version>2.0</version>
    </requires>
</plugin_manifest>

This is the minimum amount of information in a manifest file:

<name> is the display name of the plugin
<id> must be the same as the directory you just created
<requires> must include which version of Elgg your plugin requires
<author>, <version> and <description> should have some appropriate values but can be filled freely

Initializer¶

Next, create start.php in the mod/hello/ directory and copy this code into it:

<?php

elgg_register_event_handler('init', 'system', 'hello_world_init');

function hello_world_init() {

}

The above code tells Elgg that it should call the function hello_world_init() once the Elgg core system is initiated.

Registering a page handler¶

The next step is to register a page handler which has the purpose of handling request that users make to the URL https://elgg.example.com/hello.

Update start.php to look like this:

<?php

elgg_register_event_handler('init', 'system', 'hello_world_init');

function hello_world_init() {
    elgg_register_page_handler('hello', 'hello_world_page_handler');
}

function hello_world_page_handler() {
    echo elgg_view_resource('hello');
}

The call to elgg_register_page_handler() tells Elgg that it should call the function hello_world_page_handler() when a user navigates to https://elgg.example.com/hello/*.

The hello_world_page_handler() passes off rendering the actual page to a view file called hello.php.

View file¶

Create mod/hello/views/default/resources/hello.php with this content:

<?php

$params = array(
    'title' => 'Hello world!',
    'content' => 'My first page!',
    'filter' => '',
);

$body = elgg_view_layout('content', $params);

echo elgg_view_page('Hello', $body);

The code creates an array of parameters to be given to the elgg_view_layout() function, including:

The title of the page

The contents of the page

Filter which is left empty because there’s currently nothing to filter

This creates the basic layout for the page. The layout is then run through elgg_view_page() which assembles and outputs the full page.

Last step¶

Finally, activate the plugin through your Elgg administrator page: https://elgg.example.com/admin/plugins (the new plugin appears at the bottom).

You can now go to the address https://elgg.example.com/hello/ and you should see your new page!

Customizing the Home Page¶

To override the homepage, just override Elgg’s resources/index view by creating a file at /views/default/resources/index.php.

Any output from this view will become your new homepage.

You can take a similar approach with any other page in Elgg or official plugins.

Building a Blog Plugin¶

This tutorial will teach you how to create a simple blog plugin. The basic functions of the blog will be creating posts, saving them and viewing them. The plugin duplicates features that are found in the bundled blog plugin. You can disable the bundled blog plugin if you wish, but it is not necessary since the features do not conflict each other.

Contents

Create the plugin’s directory and manifest file
Create the form for creating a new blog post
Create a page for composing the blogs
Create the action file for saving the blog post
Create start.php
Create a page for viewing a blog post
Create the object view
Trying it out
Displaying a list of blog posts
The end

Prerequisites:

Install Elgg

Create the plugin’s directory and manifest file ¶

First, choose a simple and descriptive name for your plugin. In this tutorial, the name will be my_blog. Then, create a directory for your plugin in the /mod/ directory found in your Elgg installation directory. Other plugins are also located in /mod/. In this case, the name of the directory should be /mod/my_blog/. This directory is the root of your plugin and all the files that you create for the new plugin will go somewhere under it.

Next, in the root of the plugin, create the plugin’s manifest file, manifest.xml:

<?xml version="1.0" encoding="UTF-8"?>
<plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
    <name>My Blog</name>
    <id>my_blog</id>
    <author>Your Name Here</author>
    <version>0.1</version>
    <description>Adds blogging capabilities.</description>
    <requires>
        <type>elgg_release</type>
        <version>2.0</version>
    </requires>
</plugin_manifest>

See Plugins for more information about the manifest file.

Create the form for creating a new blog post ¶

Create a file at /mod/my_blog/views/default/forms/my_blog/save.php that contains the form body. The form should have input fields for the title, body and tags of the my_blog post. It does not need form tag markup.

echo elgg_view_field([
    '#type' => 'text',
    '#label' => elgg_echo('title'),
    'name' => 'title',
    'required' => true,
]);

echo elgg_view_field([
    '#type' => 'longtext',
    '#label' => elgg_echo('body'),
    'name' => 'body',
    'required' => true,
]);

echo elgg_view_field([
    '#type' => 'tags',
    '#label' => elgg_echo('tags'),
    '#help' => elgg_echo('tags:help'),
    'name' => 'tags',
]);

$submit = elgg_view_field(array(
    '#type' => 'submit',
    '#class' => 'elgg-foot',
    'value' => elgg_echo('save'),
));
elgg_set_form_footer($submit);

Notice how the form is calling elgg_view_field() to render inputs. This helper function maintains consistency in field markup, and is used as a shortcut for rendering field elements, such as label, help text, and input. See Forms + Actions.

You can see a complete list of input views in the /vendor/elgg/elgg/views/default/input/ directory.

It is recommended that you make your plugin translatable by using elgg_echo() whenever there is a string of text that will be shown to the user. Read more at Internationalization.

Create a page for composing the blogs ¶

Create the file /mod/my_blog/views/default/resources/my_blog/add.php. This page will view the form you created in the above section.

<?php
// make sure only logged in users can see this page
gatekeeper();

// set the title
$title = "Create a new my_blog post";

// start building the main column of the page
$content = elgg_view_title($title);

// add the form to the main column
$content .= elgg_view_form("my_blog/save");

// optionally, add the content for the sidebar
$sidebar = "";

// layout the page
$body = elgg_view_layout('one_sidebar', array(
   'content' => $content,
   'sidebar' => $sidebar
));

// draw the page, including the HTML wrapper and basic page layout
echo elgg_view_page($title, $body);

The function elgg_view_form("my_blog/save") views the form that you created in the previous section. It also automatically wraps the form with a <form> tag and the necessary attributes as well as anti-csrf tokens.

The form’s action will be "<?= elgg_get_site_url() ?>action/my_blog/save".

Create the action file for saving the blog post ¶

The action file will save the my_blog post to the database. Create the file /mod/my_blog/actions/my_blog/save.php:

<?php
// get the form inputs
$title = get_input('title');
$body = get_input('body');
$tags = string_to_tag_array(get_input('tags'));

// create a new my_blog object and put the content in it
$blog = new ElggObject();
$blog->title = $title;
$blog->description = $body;
$blog->tags = $tags;

// the object can and should have a subtype
$blog->subtype = 'my_blog';

// for now, make all my_blog posts public
$blog->access_id = ACCESS_PUBLIC;

// owner is logged in user
$blog->owner_guid = elgg_get_logged_in_user_guid();

// save to database and get id of the new my_blog
$blog_guid = $blog->save();

// if the my_blog was saved, we want to display the new post
// otherwise, we want to register an error and forward back to the form
if ($blog_guid) {
   system_message("Your blog post was saved.");
   forward($blog->getURL());
} else {
   register_error("The blog post could not be saved.");
   forward(REFERER); // REFERER is a global variable that defines the previous page
}

As you can see in the above code, Elgg objects have several fields built into them. The title of the my_blog post is stored in the title field while the body is stored in the description field. There is also a field for tags which are stored as metadata.

Objects in Elgg are a subclass of something called an “entity”. Users, sites, and groups are also subclasses of entity. An entity’s subtype allows granular control for listing and displaying, which is why every entity should have a subtype. In this tutorial, the subtype “my_blog” identifies a my_blog post, but any alphanumeric string can be a valid subtype. When picking subtypes, be sure to pick ones that make sense for your plugin.

The getURL method fetches the URL of the new post. It is recommended that you override this method. The overriding will be done in the start.php file.

Create start.php ¶

The /mod/my_blog/start.php file needs to register the save action you created earlier, register a page handler and override the URL generation.

<?php

// register an initializer
elgg_register_event_handler('init', 'system', 'my_blog_init');

function my_blog_init() {
    // register the save action
    elgg_register_action("my_blog/save", __DIR__ . "/actions/my_blog/save.php");

    // register the page handler
    elgg_register_page_handler('my_blog', 'my_blog_page_handler');

    // register a hook handler to override urls
    elgg_register_plugin_hook_handler('entity:url', 'object', 'my_blog_set_url');
}

Registering the save action will make it available as /action/my_blog/save. By default, all actions are available only to logged in users. If you want to make an action available to only admins or open it up to unauthenticated users, you can pass ‘admin’ or ‘public’ as the third parameter of elgg_register_action.

The URL overriding function will extract the ID of the given entity and use it to make a simple URL for the page that is supposed to view the entity. In this case the entity should of course be a my_blog post. Add this function to your start.php file:

function my_blog_set_url($hook, $type, $url, $params) {
    $entity = $params['entity'];
    if (elgg_instanceof($entity, 'object', 'my_blog')) {
        return "my_blog/view/{$entity->guid}";
    }
}

The page handler makes it possible to serve the page that generates the form and the page that views the post. The next section will show how to create the page that views the post. Add this function to your start.php file:

function my_blog_page_handler($segments) {
    if ($segments[0] == 'add') {
        echo elgg_view_resource('my_blog/add');
        return true;
    }

    else if ($segments[0] == 'view') {
        $resource_vars['guid'] = elgg_extract(1, $segments);
        echo elgg_view_resource('my_blog/view', $resource_vars);
        return true;
    }

    return false;
}

The $segments variable contains the different parts of the URL as separated by /.

Page handling functions need to return true or false. true means the page exists and has been handled by the page handler. false means that the page does not exist and the user will be forwarded to the site’s 404 page (requested page does not exist or not found). In this particular example, the URL must contain either /my_blog/add or /my_blog/view/id where id is a valid ID of an entity with the my_blog subtype. More information about page handling is at Page handler.

Create a page for viewing a blog post ¶

To be able to view a my_blog post on its own page, you need to make a view page. Create the file /mod/my_blog/views/default/resources/my_blog/view.php:

<?php

// get the entity
$guid = elgg_extract('guid', $vars);
$my_blog = get_entity($guid);

// get the content of the post
$content = elgg_view_entity($my_blog, array('full_view' => true));

$params = array(
    'title' => $my_blog->title,
    'content' => $content,
    'filter' => '',
);

$body = elgg_view_layout('content', $params);

echo elgg_view_page($my_blog->title, $body);

This page has much in common with the add.php page. The biggest differences are that some information is extracted from the my_blog entity, and instead of viewing a form, the function elgg_view_entity is called. This function gives the information of the entity to something called the object view.

Create the object view ¶

When elgg_view_entity is called or when my_blogs are viewed in a list for example, the object view will generate the appropriate content. Create the file /mod/my_blog/views/default/object/my_blog.php:

<?php

echo elgg_view('output/longtext', array('value' => $vars['entity']->description));
echo elgg_view('output/tags', array('tags' => $vars['entity']->tags));

As you can see in the previous section, each my_blog post is passed to the object view as $vars['entity']. ($vars is an array used in the views system to pass variables to a view.)

The last line takes the tags on the my_blog post and automatically displays them as a series of clickable links. Search is handled automatically.

(If you’re wondering about the “default” in /views/default/, you can create alternative views. RSS, OpenDD, FOAF, mobile and others are all valid view types.)

Trying it out ¶

Go to your Elgg site’s administration page, list the plugins and activate the my_blog plugin.

The page to create a new my_blog post should now be accessible at https://elgg.example.com/my_blog/add, and after successfully saving the post, you should see it viewed on its own page.

Displaying a list of blog posts ¶

Let’s also create a page that lists my_blog entries that have been created.

Create /mod/my_blog/views/default/resources/my_blog/all.php:

<?php
$titlebar = "All Site My_Blogs";
$pagetitle = "List of all my_blogs";

$body = elgg_list_entities(array(
    'type' => 'object',
    'subtype' => 'my_blog',
));

$body = elgg_view_title($pagetitle) . elgg_view_layout('one_column', array('content' => $body));

echo elgg_view_page($titlebar, $body);

The elgg_list_entities function grabs the latest my_blog posts and passes them to the object view file. Note that this function returns only the posts that the user can see, so access restrictions are handled transparently. The function (and its cousins) also transparently handles pagination and even creates an RSS feed for your my_blogs if you have defined that view.

The list function can also limit the my_blog posts to those of a specified user. For example, the function elgg_get_logged_in_user_guid grabs the Global Unique IDentifier (GUID) of the logged in user, and by giving that to elgg_list_entities, the list only displays the posts of the current user:

echo elgg_list_entities(array(
    'type' => 'object',
    'subtype' => 'my_blog',
    'owner_guid' => elgg_get_logged_in_user_guid()
));

Next, you will need to modify your my_blog page handler to grab the new page when the URL is set to /my_blog/all. Change the my_blog_page_handler function in start.php to look like this:

function my_blog_page_handler($segments) {
    switch ($segments[0]) {
        case 'add':
           echo elgg_view_resource('my_blog/add');
           break;

        case 'view':
            $resource_vars['guid'] = elgg_extract(1, $segments);
            echo elgg_view_resource('my_blog/view', $resource_vars);
            break;

        case 'all':
        default:
           echo elgg_view_resource('my_blog/all');
           break;
    }

    return true;
}

Now, if the URL contains /my_blog/all, the user will see an “All Site My_Blogs” page. Because of the default case, the list of all my_blogs will also be shown if the URL is something invalid, like /my_blog or /my_blog/xyz.

You might also want to update the object view to handle different kinds of viewing, because otherwise the list of all my_blogs will also show the full content of all my_blogs. Change /mod/my_blog/views/default/object/my_blog.php to look like this:

<?php
$full = elgg_extract('full_view', $vars, FALSE);

// full view
if ($full) {
    echo elgg_view('output/longtext', array('value' => $vars['entity']->description));
    echo elgg_view('output/tags', array('tags' => $vars['entity']->tags));

// list view or short view
} else {
    // make a link out of the post's title
    echo elgg_view_title(
        elgg_view('output/url', array(
            'href' => $vars['entity']->getURL(),
            'text' => $vars['entity']->title,
            'is_trusted' => true
    )));
    echo elgg_view('output/tags', array('tags' => $vars['entity']->tags));
}

Now, if full_view is true (as it was pre-emptively set to be in this section), the object view will show the post’s content and tags (the title is shown by view.php). Otherwise the object view will render just the title and tags of the post.

The end ¶

There’s much more that could be done, but hopefully this gives you a good idea of how to get started.

Integrating a Rich Text Editor¶

Build your own wysiwyg plugin.

Elgg is bundled with a plugin for CKEditor, and previously shipped with TinyMCE support. However, if you have a wysiwyg that you prefer, you could use this tutorial to help you build your own.

All forms in Elgg should try to use the provided input views located in views/default/input. If these views are used, then it is simple for plugin authors to replace a view, in this case input/longtext, with their wysiwyg.

Add the WYSIWYG library code¶

Now you need to upload TinyMCE into a directory in your plugin. We strongly encourage you to use composer to manage third-party dependencies, since it is so much easier to upgrade and maintain that way:

.. code:: shell

composer require bower-asset/tinymce

Tell Elgg when and how to load TinyMCE¶

Now that you have:

created your start file

intialized the plugin

uploaded the wysiwyg code

It is time to tell Elgg how to apply TinyMCE to longtext fields.

We’re going to do that by extending the input/longtext view and including some javascript. Create a view tinymce/longtext and add the following code:

<?php

    /**
     * Elgg long text input with the tinymce text editor intacts
     * Displays a long text input field
     *
     * @package ElggTinyMCE
     *
     *
     */

?>
<!-- include tinymce -->
<script language="javascript" type="text/javascript" src="<?php echo $vars['url']; ?>mod/tinymce/tinymce/jscripts/tiny_mce/tiny_mce.js"></script>
<!-- intialise tinymce, you can find other configurations here http://wiki.moxiecode.com/examples/tinymce/installation_example_01.php -->
<script language="javascript" type="text/javascript">
   tinyMCE.init({
    mode : "textareas",
    theme : "advanced",
    theme_advanced_buttons1 : "bold,italic,underline,separator,strikethrough,justifyleft,justifycenter,justifyright, justifyfull,bullist,numlist,undo,redo,link,unlink,image,blockquote,code",
    theme_advanced_buttons2 : "",
    theme_advanced_buttons3 : "",
    theme_advanced_toolbar_location : "top",
    theme_advanced_toolbar_align : "left",
    theme_advanced_statusbar_location : "bottom",
    theme_advanced_resizing : true,
    extended_valid_elements : "a[name|href|target|title|onclick],img[class|src|border=0|alt|title|hspace|vspace|width|height|align|onmouseover|onmouseout|name],
hr[class|width|size|noshade],font[face|size|color|style],span[class|align|style]"
});
</script>

Then, in your plugin’s init function, extend the input/longtext view

function tinymce_init() {
    elgg_extend_view('input/longtext', 'tinymce/longtext');
}

That’s it! Now every time someone uses input/longtext, TinyMCE will be loaded and applied to that textarea.

Basic Widget¶

Create a widget that will display “Hello, World!” and optionally any text the user wants.

In Elgg, widgets are those components that you can drag onto your profile or admin dashboard.

This tutorial assumes you are familiar with basic Elgg concepts such as:

Views

Plugins

You should review those if you get confused along the way.

Contents

Adding the widget view code
Registering your widget
Allow user customization

Adding the widget view code ¶

Elgg automatically scans particular directories under plugins looking for particular files. Views make it easy to add your display code or do other things like override default Elgg behavior. For now, we will just be adding the view code for your widget. Create a file at /views/default/widgets/helloworld/content.php. “helloworld” will be the name of your widget within the hello plugin. In this file add the code:

<?php

echo "Hello, world!";

This will add these words to the widget canvas when it is drawn. Elgg takes care of loading the widget.

Registering your widget ¶

Elgg needs to be told explicitly that the plugin contains a widget so that it will scan the widget views directory. This is done by calling the elgg_register_widget_type() function. Edit /start.php. In it add these lines:

<?php

function hello_init() {
    elgg_register_widget_type([
        'id' => 'helloworld',
        'name' => 'Hello, world!',
        'description' => 'The "Hello, world!" widget',
    ]);
}

elgg_register_event_handler('init', 'system', 'hello_init');

Now go to your profile page using a web browser and add the “hello, world” widget. It should display “Hello, world!”.

Note

For real widgets, it is always a good idea to support Internationalization.

Allow user customization ¶

Click on the edit link on the toolbar of the widget that you’ve created. You will notice that the only control it gives you by default is over access (over who can see the widget).

Suppose you want to allow the user to control what greeting is displayed in the widget. Just as Elgg automatically loads content.php when viewing a widget, it loads edit.php when a user attempts to edit a widget. Put the following code into /views/default/widgets/helloworld/edit.php:

<div>
    <label>Message:</label>
    <?php
        //This is an instance of the ElggWidget class that represents our widget.
        $widget = $vars['entity'];

        // Give the user a plain text box to input a message
        echo elgg_view('input/text', array(
            'name' => 'params[message]',
            'value' => $widget->message,
            'class' => 'hello-input-text',
        ));
    ?>
</div>

Notice the relationship between the values passed to the ‘name’ and the ‘value’ fields of input/text. The name of the input text box is params[message] because Elgg will automatically handle widget variables put in the array params. The actual php variable name will be message. If we wanted to use the field greeting instead of message we would pass the values params[greeting] and $widget->greeting respectively.

The reason we set the ‘value’ option of the array is so that the edit view remembers what the user typed in the previous time he changed the value of his message text.

Now to display the user’s message we need to modify content.php to use this message variable. Edit /views/default/widgets/helloworld/content.php and change it to:

<?php

$widget = $vars['entity'];

// Always use the corresponding output/* view for security!
echo elgg_view('output/text', array('value' => $widget->message));

You should now be able to enter a message in the text box and see it appear in the widget.

Design Docs¶

Gain a deep understanding of how Elgg works and why it’s built the way it is.

Actions¶

Actions are the primary way users interact with an Elgg site.

Overview¶

An action in Elgg is the code that runs to make changes to the database when a user does something. For example, logging in, posting a comment, and making a blog post are actions. The action script processes input, makes the appropriate modifications to the database, and provides feedback to the user about the action.

Action Handler¶

Actions are registered during the boot process by calling elgg_register_action(). All actions URLs start with action/ and are served by Elgg’s front end controller through the action service. This approach is different from traditional PHP applications that send information to a specific file. The action service performs CSRF security checks, and calls the registered action script file, then optionally forwards the user to a new page. By using the action service instead of a single script file, Elgg automatically provides increased security and extensibility.

In Elgg 1.8 and before, actions were handled by an action handler script in `engine/handlers/action_handler.php. This required specific rewrite rules for URLs beginning with /action/.

See Forms + Actions for details on how to register and construct an action. To look at the core actions, check out the directory /actions.

Database¶

A thorough discussion of Elgg’s data model design and motivation.

Contents

Overview ¶

In Elgg, everything runs on a unified data model based on atomic units of data called entities.

Plugins are discouraged from interacting directly with the database, which creates a more stable system and a better user experience becase content created by different plugins can be mixed together in consistent ways. With this approach, plugins are faster to develop, and are at the same time much more powerful.

Every entity in the system inherits the ElggEntity class. This class controls access permissions, ownership

You can extend entities with extra information in two ways:

Metadata: This is information describing the entity, usually: added by the author of the entity when the entity is created. For example, tags, an ISBN number, a file location, or source language is metadata.
Annotations: This is information about the entity, usually: added by a third party after the entity is created. For example, ratings, likes, and votes are annotations. (Comments were before 1.9.)

Datamodel ¶

The Elgg data model diagram

Entities ¶

ElggEntity is the base class for the Elgg data model and supports a common set of properties and methods.

A numeric Globally Unique IDentifier (See GUIDs).
Access permissions. (When a plugin requests data, it never gets to touch data that the current user doesn’t have permission to see.)
An arbitrary subtype (more below).
An owner.
The site that the entity belongs to.
A container, used to associate content with a group or a user.

Types ¶

Actual entities will be instances of four different subclasses, each having a distinct type property and their own additional properties and methods.

Type	PHP class	Represents
object	`ElggObject`	Most user-created content, like blog posts, uploads, and bookmarks.
group	`ElggGroup`	An organized group of users with its own profile page
user	`ElggUser`	A system user
site	`ElggSite`	The site served by the Elgg installation

Each has its own extended API. E.g. objects have a title and description, users have a username and a way to set their password, and so on.

Subtypes ¶

Each entity also has a custom string subtype, which plugins use to further specialize the entity. Elgg makes it easy to query specific subtypes as well as assign them special behaviors and views.

Subtypes are most commonly given to instances of ElggObject to denote the kind of content created. E.g. the blog plugin creates objects with subtype "blog".

For historic reasons, the subtype API is a bit complex, but boils down to: write to ->subtype before saving, otherwise always read getSubtype(). Below are more details.

Subtype Gotchas ¶

Before an entity’s save() method is called, the subtype can be set by writing a string to the subtype property.
Subtype cannot be changed after saving.
After saving, you must always use getSubtype() to read it.
If no subtype was set, "" is returned, however some parts of the Elgg API (like Views) may map this value to the string "default". E.g. a group with getSubtype() === "" will be rendered using the view "group/default".
Read carefully the documentation for elgg_get_entities() before trying to match subtypes; this
API is a bit of a minefield. E.g. you cannot use "" to fetch entities with the default subtype.

GUIDs ¶

A GUID is an integer that uniquely identifies every entity in an Elgg installation (a Globally Unique IDentifier). It’s assigned automatically when the entity is first saved and can never be changed.

Some Elgg API functions work with GUIDs instead of ElggEntity objects.

ElggObject ¶

The ElggObject entity type represents arbitrary content within an Elgg install; things like blog posts, uploaded files, etc.

Beyond the standard ElggEntity properties, ElggObjects also support:

title The title of the object (HTML escaped text)
description A description of the object (HTML)

Most other data about the object is generally stored via metadata.

ElggUser ¶

The ElggUser entity type represents users within an Elgg install. These will be set to disabled until their accounts have been activated (unless they were created from within the admin panel).

Beyond the standard ElggEntity properties, ElggUsers also support:

name The user’s plain text name. e.g. “Hugh Jackman”
username Their login name. E.g. “hjackman”
password A hashed version of their password
email Their email address
language Their default language code.
code Their session code (moved to a separate table in 1.9).
last_action The UNIX timestamp of the last time they loaded a page
prev_last_action The previous value of last_action
last_login The UNIX timestamp of their last log in
prev_last_login the previous value of last_login

ElggSite ¶

The ElggSite entity type represents sites within your Elgg install. Most installs will have only one.

Beyond the standard ElggEntity properties, ElggSites also support:

name The site name
description A description of the site
url The address of the site

ElggGroup ¶

The ElggGroup entity type represents an association of Elgg users. Users can join, leave, and post content to groups.

Beyond the standard ElggEntity properties, ElggGroups also support:

name The group’s name (HTML escaped text)
description A description of the group (HTML)

ElggGroup has addition methods to manage content and membership.

The Groups plugin ¶

Not to be confused with the entity type ElggGroup, Elgg comes with a plugin called “Groups” that provides a default UI/UX for site users to interact with groups. Each group is given a discussion forum and a profile page linking users to content within the group.

You can alter the user experience via the traditional means of extending plugins or completely replace the Groups plugin with your own.

Because ElggGroup can be subtyped like all other ElggEntities, you can have multiple types of groups running on the same site.

Writing a group-aware plugin ¶

Plugin owners need not worry too much about writing group-aware functionality, but there are a few key points:

Adding content¶

By passing along the group as container_guid via a hidden input field, you can use a single form and action to add both user and group content.

Use can_write_to_container to determine whether or not the current user has the right to add content to a group.

Be aware that you will then need to pass the container GUID or username to the page responsible for posting and the accompanying value, so that this can then be stored in your form as a hidden input field, for easy passing to your actions. Within a “create” action, you’ll need to take in this input field and save it as a property of your new element (defaulting to the current user’s container):

$user = elgg_get_logged_in_user_entity();
$container_guid = (int)get_input('container_guid');
if ($container_guid) {
    if (!can_write_to_container($user->guid, $container_guid)) {
        // register error and forward
    }
} else {
    $container_guid = elgg_get_logged_in_user_guid();
}

$object = new ElggObject;
$object->container_guid = $container_guid;

...

$container = get_entity($container_guid);
forward($container->getURL());

Usernames and page ownership¶

Groups have a simulated username of the form group:GUID, which you can get the value of by checking $group->username. If you pass this username to a page on the URL line as part of the username variable (i.e., /yourpage?username=group:nnn), Elgg will automatically register that group as being the owner of the page (unless overridden).

Juggling users and groups¶

In fact, [[Engine/DataModel/Entities/ElggGroup|ElggGroup]] simulates most of the methods of [[Engine/DataModel/Entities/ElggUser|ElggUser]]. You can grab the icon, name etc using the same calls, and if you ask for a group’s friends, you’ll get its members. This has been designed specifically for you to alternate between groups and users in your code easily.

Menu options¶

*This section is deprecated as of Elgg 1.8*

The final piece of the puzzle, for default groups, is to add a link to your functionality from the group’s profile. Here we’ll use the file plugin as an example.

This involves creating a view within your plugin - in this case file/menu - which will extend the group’s menu. File/menu consists of a link within paragraph tags that points to the file repository of the page_owner():

<p>
  <a href="<?php echo $vars['url']; ?>pg/file/<?php echo page_owner_entity()->username; ?>">
    <?php echo elgg_echo("file"); ?>
  </a>
</p>

You can then extend the group’s menu view with this one, within your plugin’s input function (in this case file_init):

extend_view('groups/menu/links', 'file/menu');

Ownership ¶

Entities have a owner_guid GUID property, which defines its owner. Typically this refers to the GUID of a user, although sites and users themselves often have no owner (a value of 0).

The ownership of an entity dictates, in part, whether or not you can access or edit that entity.

Containers ¶

In order to easily search content by group or by user, content is generally set to be “contained” by either the user who posted it, or the group to which the user posted. This means the new object’s container_guid property will be set to the GUID of the current ElggUser or the target ElggGroup.

E.g., three blog posts may be owned by different authors, but all be contained by the group they were posted to.

Note: This is not always true. Comment entities are contained by the object commented upon, and in some 3rd party plugins the container may be used to model a parent-child relationship between entities (e.g. a “folder” object containing a file object).

Annotations ¶

Annotations are pieces of data attached to an entity that allow users to leave ratings, or other relevant feedback. A poll plugin might register votes as annotations. Before Elgg 1.9, comments and group discussion replies were stored as annotations.

Annotations are stored as instances of the ElggAnnotation class.

Each annotation has:

An internal annotation type (like comment)
A value (which can be a string or integer)
An access permission distinct from the entity it’s attached to
An owner

Like metadata, values are stored as strings unless the value given is a PHP integer (is_int($value) is true), or unless the $vartype is manually specified as integer.

Adding an annotation ¶

The easiest way to annotate is to use the annotate method on an entity, which is defined as:

public function annotate(
    $name,           // The name of the annotation type (eg 'comment')
    $value,          // The value of the annotation
    $access_id = 0,  // The access level of the annotation
    $owner_id = 0,   // The annotation owner, defaults to current user
    $vartype = ""    // 'text' or 'integer'
)

For example, to leave a rating on an entity, you might call:

$entity->annotate('rating', $rating_value, $entity->access_id);

Reading annotations ¶

To retrieve annotations on an object, you can call the following method:

$annotations = $entity->getAnnotations(
    $name,    // The type of annotation
    $limit,   // The number to return
    $offset,  // Any indexing offset
    $order,   // 'asc' or 'desc' (default 'asc')
);

If your annotation type largely deals with integer values, a couple of useful mathematical functions are provided:

$averagevalue = $entity->getAnnotationsAvg($name);  // Get the average value
$total = $entity->getAnnotationsSum($name);         // Get the total value
$minvalue = $entity->getAnnotationsMin($name);      // Get the minimum value
$maxvalue = $entity->getAnnotationsMax($name);      // Get the maximum value

Useful helper functions ¶

Comments¶

If you want to provide comment functionality on your plugin objects, the following function will provide the full listing, form and actions:

function elgg_view_comments(ElggEntity $entity)

Metadata ¶

Metadata in Elgg allows you to store extra data on an entity beyond the built-in fields that entity supports. For example, ElggObjects only support the basic entity fields plus title and description, but you might want to include tags or an ISBN number. Similarly, you might want users to be able to save a date of birth.

Under the hood, metadata is stored as an instance of the ElggMetadata class, but you don’t need to worry about that in practice (although if you’re interested, see the ElggMetadata class reference). What you need to know is:

Metadata has an owner and access ID (see note below), both of which may be different to the owner of the entity it’s attached to
You can potentially have multiple items of each type of metadata attached to a single entity
Like annotations, values are stored as strings unless the value given is a PHP integer (is_int($value) is true), or unless the $value_type is manually specified as integer (see below).

Note

Metadata’s access_id value will be ignored in Elgg 3.0 and all metadata values will be available in all contexts.

The simple case ¶

Adding metadata¶

To add a piece of metadata to an entity, just call:

$entity->metadata_name = $metadata_value;

For example, to add a date of birth to a user:

$user->dob = $dob_timestamp;

Or to add a couple of tags to an object:

$object->tags = array('tag one', 'tag two', 'tag three');

When adding metadata like this:

The owner is set to the currently logged-in user
Access permissions are inherited from the entity (see note below)
Reassigning a piece of metadata will overwrite the old value

This is suitable for most purposes. Be careful to note which attributes are metadata and which are built in to the entity type that you are working with. You do not need to save an entity after adding or updating metadata. You do need to save an entity if you have changed one of its built in attributes. As an example, if you changed the access id of an ElggObject, you need to save it or the change isn’t pushed to the database.

Note

Metadata’s access_id value will be ignored in Elgg 3.0 and all metadata values will be available in all contexts.

Reading metadata¶

To retrieve metadata, treat it as a property of the entity:

$tags_value = $object->tags;

Note that this will return the absolute value of the metadata. To get metadata as an ElggMetadata object, you will need to use the methods described in the finer control section below.

If you stored multiple values in this piece of metadata (as in the “tags” example above), you will get an array of all those values back. If you stored only one value, you will get a string or integer back. Storing an array with only one value will return a string back to you. E.g.

$object->tags = array('tag');
$tags = $object->tags;
// $tags will be the string "tag", NOT array('tag')

To always get an array back, simply cast to an array;

$tags = (array)$object->tags;

Finer control ¶

Adding metadata¶

If you need more control, for example to assign an access ID other than the default, you can use the create_metadata function, which is defined as follows:

function create_metadata(
    $entity_guid,           // The GUID of the parent entity
    $name,                  // The name of the metadata (eg 'tags')
    $value,                 // The metadata value
    $value_type,            // Currently either 'text' or 'integer'
    $owner_guid,            // The owner of the metadata
    $access_id = 0,         // The access restriction
    $allow_multiple = false // Do we have more than one value?
    )

For single values, you can therefore write metadata as follows (taking the example of a date of birth attached to a user):

create_metadata($user_guid, 'dob', $dob_timestamp, 'integer', $_SESSION['guid'], $access_id);

Note

$access_id will be ignored in Elgg 3.0 and all metadata values will be available in all contexts. Always set it to ACCESS_PUBLIC for compatibility with Elgg 3.0.

For multiple values, you will need to iterate through and call create_metadata on each one. The following piece of code comes from the profile save action:

$i = 0;
foreach ($value as $interval) {
    $i++;
    $multiple = ($i != 1);
    create_metadata($user->guid, $shortname, $interval, 'text', $user->guid, $access_id, $multiple);
}

Note that the allow multiple setting is set to false in the first iteration and true thereafter.

Reading metadata¶

elgg_get_metadata is the best function for retrieving metadata as ElggMetadata objects:

E.g., to retrieve a user’s DOB

elgg_get_metadata(array(
    'metadata_name' => 'dob',
    'metadata_owner_guid' => $user_guid,
));

Or to get all metadata objects:

elgg_get_metadata(array(
    'metadata_owner_guid' => $user_guid,
    'limit' => 0,
));

Common mistakes ¶

“Appending” metadata¶

Note that you cannot “append” values to metadata arrays as if they were normal php arrays. For example, the following will not do what it looks like it should do.

$object->tags[] = "tag four";

Trying to store hashmaps¶

Elgg does not support storing ordered maps (name/value pairs) in metadata. For example, the following does not work as you might first expect it to:

// Won't work!! Only the array values are stored
$object->tags = array('one' => 'a', 'two' => 'b', 'three' => 'c');

You can instead store the information like so:

$object->one = 'a';
$object->two = 'b';
$object->three = 'c';

Storing GUIDs in metadata¶

Though there are some cases to store entity GUIDs in metadata, Relationships are a much better construct for relating entities to each other.

Relationships ¶

Relationships allow you to bind entities together. Examples: an artist has fans, a user is a member of an organization, etc.

The class ElggRelationship models a directed relationship between two entities, making the statement:

“{subject} is a {noun} of {target}.”

API name	Models	Represents
`guid_one`	The subject	Which entity is being bound
`relationship`	The noun	The type of relationship
`guid_two`	The target	The entity to which the subject is bound

The type of relationship may alternately be a verb, making the statement:

“{subject} {verb} {target}.”

E.g. User A “likes” blog post B

Each relationship has direction. Imagine an archer shoots an arrow at a target; The arrow moves in one direction, binding the subject (the archer) to the target.

A relationship does not imply reciprocity. A follows B does not imply that B follows A.

Relationships_ do not have access control. They’re never hidden from view and can be edited with code at any privilege level, with the caveat that the entities in a relationship may be invisible due to access control!

Working with relationships ¶

Creating a relationship¶

E.g. to establish that “$user is a fan of $artist” (user is the subject, artist is the target):

// option 1
$success = add_entity_relationship($user->guid, 'fan', $artist->guid);

// option 2
$success = $user->addRelationship($artist->guid, 'fan');

This triggers the event [create, relationship], passing in the created ElggRelationship object. If a handler returns false, the relationship will not be created and $success will be false.

Verifying a relationship¶

E.g. to verify that “$user is a fan of $artist”:

if (check_entity_relationship($user->guid, 'fan', $artist->guid)) {
    // relationship exists
}

Note that, if the relationship exists, check_entity_relationship() returns an ElggRelationship object:

$relationship = check_entity_relationship($user->guid, 'fan', $artist->guid);
if ($relationship) {
    // use $relationship->id or $relationship->time_created
}

Deleting a relationship¶

E.g. to be able to assert that “$user is no longer a fan of $artist”:

$was_removed = remove_entity_relationship($user->guid, 'fan', $artist->guid);

This triggers the event [delete, relationship], passing in the associated ElggRelationship object. If a handler returns false, the relationship will remain, and $was_removed will be false.

Other useful functions:

delete_relationship() : delete by ID
remove_entity_relationships() : delete those relating to an entity (note: in versions before Elgg 1.9, this did not trigger delete events)

Access Control ¶

Granular access controls are one of the fundamental design principles in Elgg, and a feature that has been at the centre of the system throughout its development. The idea is simple: a user should have full control over who sees an item of data he or she creates.

Access controls in the data model ¶

In order to achieve this, every entity, annotation and piece of metadata contains an access_id property, which in turn corresponds to one of the pre-defined access controls or an entry in the access_collections database table.

Pre-defined access controls¶

ACCESS_PRIVATE (value: 0) Private.
ACCESS_LOGGED_IN (value: 1) Logged in users.
ACCESS_PUBLIC (value: 2) Public data.
ACCESS_FRIENDS (value: -2) Owner and his/her friends.

User defined access controls¶

You may define additional access groups and assign them to an entity, annotation or metadata. A number of functions have been defined to assist you; see the access library reference for more information.

How access affects data retrieval ¶

All data retrieval functions above the database layer - for example get_entities and its cousins - will only return items that the current user has access to see. It is not possible to retrieve items that the current user does not have access to. This makes it very hard to create a security hole for retrieval.

Write access ¶

The following rules govern write access:

The owner of an entity can always edit it
The owner of a container can edit anything therein (note that this does not mean that the owner of a group can edit anything therein)
Admins can edit anything

You can override this behaviour using a plugin hook called permissions_check, which passes the entity in question to any function that has announced it wants to be referenced. Returning true will allow write access; returning false will deny it. See the plugin hook reference for permissions_check for more details.

See also

Access library reference

Schema ¶

The database contains a number of primary tables and secondary tables. Its schema table is stored in /engine/schema/mysql.sql.

Each table is prefixed by “prefix_”, this is replaced by the Elgg framework during installation.

Main tables ¶

This is a description of the main tables. Keep in mind that in a given Elgg installation, the tables will have a prefix (typically “elgg_”).

Table: entities¶

This is the main Entities table containing Elgg users, sites, objects and groups. When you first install Elgg this is automatically populated with your first site.

It contains the following fields:

guid An auto-incrementing counter producing a GUID that uniquely identifies this entity in the system.
type The type of entity - object, user, group or site
subtype A reference to the entity_subtypes table, or 0 for the default subtype.
owner_guid The GUID of the owner’s entity.
site_guid The site the entity belongs to.
container_guid The GUID this entity is contained by - either a user or a group.
access_id Access controls on this entity.
time_created Unix timestamp of when the entity is created.
time_updated Unix timestamp of when the entity was updated.
enabled If this is ‘yes’ an entity is accessible, if ‘no’ the entity has been disabled (Elgg treats it as if it were deleted without actually removing it from the database).

Table: entity_subtypes¶

This table contains entity subtype information:

id A counter.
type The type of entity - object, user, group or site.
subtype The subtype name as a string.
class Optional class name if this subtype is linked with a class

Table: metadata¶

This table contains Metadata, extra information attached to an entity.

id A counter.
entity_guid The entity this is attached to.
name_id A link to the metastrings table defining the name table.
value_id A link to the metastrings table defining the value.
value_type The value class, either text or an integer.
owner_guid The owner GUID of the owner who set this item of metadata.
access_id An Access controls on this item of metadata.
time_created Unix timestamp of when the metadata is created.
enabled If this is ‘yes’ an item is accessible, if ‘no’ the item has been deleted.

Table: annotations¶

This table contains Annotations, this is distinct from Metadata.

id A counter.
entity_guid The entity this is attached to.
name_id A link to the metastrings table defining the type of annotation.
value_id A link to the metastrings table defining the value.
value_type The value class, either text or an integer.
owner_guid The owner GUID of the owner who set this item of metadata.
access_id An Access controls on this item of metadata.
time_created Unix timestamp of when the metadata is created.
enabled If this is ‘yes’ an item is accessible, if ‘no’ the item has been deleted.

Table: relationships¶

This table defines Relationships, these link one entity with another.

guid_one The GUID of the subject entity.
relationship The type of the relationship.
guid_two The GUID of the target entity.

Table: objects_entity¶

Extra information specifically relating to objects. These are split in order to reduce load on the metadata table and make an obvious difference between attributes and metadata.

Table: sites_entity¶

Extra information specifically relating to sites. These are split in order to reduce load on the metadata table and make an obvious difference between attributes and metadata.

Table: users_entity¶

Extra information specifically relating to users. These are split in order to reduce load on the metadata table and make an obvious difference between attributes and metadata.

Table: groups_entity¶

Extra information specifically relating to groups. These are split in order to reduce load on the metadata table and make an obvious difference between attributes and metadata.

Table: metastrings¶

Metastrings contain the actual string of metadata which is linked to by the metadata and annotations tables.

This is to avoid duplicating strings, saving space and making database lookups more efficient.

Events and Plugin Hooks¶

Contents

Overview
- Elgg Events vs. Plugin Hooks
Elgg Events
Plugin Hooks

Overview ¶

Elgg has an event system that can be used to replace or extend core functionality.

Plugins influence the system by creating handlers (callables such as functions and methods) and registering them to handle two types of events: Elgg Events and Plugin Hooks.

When an event is triggered, a set of handlers is executed in order of priority. Each handler is passed arguments and has a chance to influence the process. After execution, the “trigger” function returns a value based on the behavior of the handlers.

Elgg Events vs. Plugin Hooks ¶

The main differences between Elgg Events and Plugin Hooks are:

Most Elgg events can be cancelled; unless the event is an “after” event, a handler that returns false can cancel the event, and no more handlers are called.
Plugin hooks cannot be cancelled; all handlers are always called.
Plugin hooks pass an arbitrary value through the handlers, giving each a chance to alter along the way.

Elgg Events ¶

Elgg Events are triggered when an Elgg object is created, updated, or deleted; and at important milestones while the Elgg framework is loading. Examples: a blog post being created or a user logging in.

Unlike Plugin Hooks, most Elgg events can be cancelled, halting the execution of the handlers, and possibly cancelling an some action in the Elgg core.

Each Elgg event has a name and an object type (system, user, object, relationship name, annotation, group) describing the type of object passed to the handlers.

Before and After Events ¶

Some events are split into “before” and “after”. This avoids confusion around the state of the system while in flux. E.g. Is the user logged in during the [login, user] event?

Before Events have names ending in “:before” and are triggered before something happens. Like traditional events, handlers can cancel the event by returning false.

After Events, with names ending in “:after”, are triggered after something happens. Unlike traditional events, handlers cannot cancel these events; all handlers will always be called.

Where before and after events are available, developers are encouraged to transition to them, though older events will be supported for backwards compatibility.

Elgg Event Handlers ¶

Elgg event handlers should have the following prototype:

/**
 * @param string $event       The name of the event
 * @param string $object_type The type of $object (e.g. "user", "group")
 * @param mixed  $object      The object of the event
 *
 * @return bool if false, the handler is requesting to cancel the event
 */
function event_handler($event, $object_type, $object) {
    ...
}

If the handler returns false, the event is cancelled, preventing execution of the other handlers. All other return values are ignored.

Register to handle an Elgg Event ¶

Register your handler to an event using elgg_register_event_handler:

elgg_register_event_handler($event, $object_type, $handler, $priority);

Parameters:

$event The event name.
$object_type The object type (e.g. “user” or “object”) or ‘all’ for all types on which the event is fired.
$handler The callback of the handler function.
$priority The priority - 0 is first and the default is 500.

Object here does not refer to an ElggObject but rather a string describing any object in the framework: system, user, object, relationship, annotation, group.

Example:

// Register the function myPlugin_handle_login() to handle the
// user login event with priority 400.
elgg_register_event_handler('login', 'user', 'myPlugin_handle_login', 400);

Warning

If you handle the “update” event on an object, avoid calling save() in your event handler. For one it’s probably not necessary as the object is saved after the event completes, but also because save() calls another “update” event and makes $object->getOriginalAttributes() no longer available.

Trigger an Elgg Event ¶

You can trigger a custom Elgg event using elgg_trigger_event:

if (elgg_trigger_event($event, $object_type, $object)) {
    // Proceed with doing something.
} else {
    // Event was cancelled. Roll back any progress made before the event.
}

For events with ambiguous states, like logging in a user, you should use Before and After Events by calling elgg_trigger_before_event or elgg_trigger_after_event. This makes it clear for the event handler what state to expect and which events can be cancelled.

// handlers for the user, login:before event know the user isn't logged in yet.
if (!elgg_trigger_before_event('login', 'user', $user)) {
        return false;
}

// handlers for the user, login:after event know the user is logged in.
elgg_trigger_after_event('login', 'user', $user);

Parameters:

$event The event name.
$object_type The object type (e.g. “user” or “object”).
$object The object (e.g. an instance of ElggUser or ElggGroup)

The function will return false if any of the selected handlers returned false and the event is stoppable, otherwise it will return true.

Plugin Hooks ¶

Plugin Hooks provide a way for plugins to collaboratively determine or alter a value. For example, to decide whether a user has permission to edit an entity or to add additional configuration options to a plugin.

A plugin hook has a value passed into the trigger function, and each handler has an opportunity to alter the value before it’s passed to the next handler. After the last handler has completed, the final value is returned by the trigger.

Plugin Hook Handlers ¶

Plugin hook handlers should have the following prototype:

/**
 * @param string $hook    The name of the plugin hook
 * @param string $type    The type of the plugin hook
 * @param mixed  $value   The current value of the plugin hook
 * @param mixed  $params  Data passed from the trigger
 *
 * @return mixed if not null, this will be the new value of the plugin hook
 */
function plugin_hook_handler($hook, $type, $value, $params) {
    ...
}

If the handler returns no value (or null explicitly), the plugin hook value is not altered. Otherwise the return value becomes the new value of the plugin hook. It will then be passed to the next handler as $value.

Register to handle a Plugin Hook ¶

Register your handler to a plugin hook using elgg_register_plugin_hook_handler:

elgg_register_plugin_hook_handler($hook, $type, $handler, $priority);

Parameters:

$hook The name of the plugin hook.
$type The type of the hook or ‘all’ for all types.
$handler The callback of the handler function.
$priority The priority - 0 is first and the default is 500.

Type can vary in meaning. It may mean an Elgg entity type or something specific to the plugin hook name.

Example:

// Register the function myPlugin_hourly_job() to be called with priority 400.
elgg_register_plugin_hook_handler('cron', 'hourly', 'myPlugin_hourly_job', 400);

Trigger a Plugin Hook ¶

You can trigger a custom plugin hook using elgg_trigger_plugin_hook:

// filter $value through the handlers
$value = elgg_trigger_plugin_hook($hook, $type, $params, $value);

Parameters:

$hook The name of the plugin hook.
$type The type of the hook or ‘all’ for all types.
$params Arbitrary data passed from the trigger to the handlers.
$value The initial value of the plugin hook.

Warning

The $params and $value arguments are reversed between the plugin hook handlers and trigger functions!

Unregister Event/Hook Handlers ¶

The functions elgg_unregister_event_handler and elgg_unregister_plugin_hook_handler can be used to remove handlers already registered by another plugin or Elgg core. The parameters are in the same order as the registration functions, except there’s no priority parameter.

elgg_unregister_event_handler('login', 'user', 'myPlugin_handle_login');

Anonymous functions or invokable objects cannot be unregistered, but dynamic method callbacks can be unregistered by giving the static version of the callback:

$obj = new MyPlugin\Handlers();
elgg_register_plugin_hook_handler('foo', 'bar', [$obj, 'handleFoo']);

// ... elsewhere

elgg_unregister_plugin_hook_handler('foo', 'bar', 'MyPlugin\Handlers::handleFoo');

Even though the event handler references a dynamic method call, the code above will successfully remove the handler.

Handler Calling Order ¶

Handlers are called first in order of priority, then registration order.

Note

Before Elgg 2.0, registering with the all keywords caused handlers to be called later, even if they were registered with lower priorities.

Internationalization¶

Elgg 1.0+ departs from previous versions in that it uses a custom text array rather than gettext. This improves system performance and reliability of the translation system.

TODO: more plz

AMD¶

Overview¶

There are two JavaScript system in Elgg: the deprecated 1.8 system, and the newer AMD (Asynchronous Module Definition) compatible system introduced in 1.9.

This discusses the benefits of using AMD in Elgg.

Why AMD?¶

We have been working hard to make Elgg’s JavaScript more maintainable and useful. We made some strides in 1.8 with the introduction of the “elgg” JavaScript object and library, but have quickly realized the approach we were taking was not scalable.

The size of JS on the web is growing quickly, and JS in Elgg is growing too. We want Elgg to be able to offer a solution that makes JS development as productive and maintainable as possible going forward.

The reasons to choose AMD are plenteous and well-documented. Let’s highlight just a few of the most relevant reasons as they relate to Elgg specifically.

1. Simplified dependency management¶

AMD modules load asynchronously and execute as soon as their dependencies are available, so this eliminates the need to specify “priority” and “location” when registering JS libs in Elgg. Also, you don’t need to worry about explicitly loading a module’s dependencies in PHP. The AMD loader (RequireJS in this case) takes care of all that hassle for you. It’s also possible have text dependencies with the RequireJS text plugin, so client-side templating should be a breeze.

2. AMD works in all browsers. Today.¶

Elgg developers are already writing lots of JavaScript. We know you want to write more. We cannot accept waiting 5-10 years for a native JS modules solution to be available in all browsers before we can organize our JavaScript in a maintainable way.

3. You do not need a build step to develop in AMD.¶

We like the edit-refresh cycle of web development. We wanted to make sure everyone developing in Elgg could continue experiencing that joy. Synchronous module formats like Closure or CommonJS just weren’t an option for us. But even though AMD doesn’t require a build step, it is still very build-friendly. Because of the define() wrapper, it’s possible to concatenate multiple modules into a single file and ship them all at once in a production environment. [1]

AMD is a battle-tested and well thought out module loading system for the web today. We’re very thankful for the work that has gone into it, and are excited to offer it as the standard solution for JavaScript development in Elgg starting with Elgg 1.9.

[1]	This is not currently supported by Elgg core, but we’ll be looking into it since reducing round-trips is critical for a good first-view experience, especially on mobile devices.

Security¶

Elgg’s approach to the various security issues common to all web applications.

Tip

To report a potential vulnerability in Elgg, email security@elgg.org.

Contents

Passwords
Sessions
Alternative authentication
HTTPS
XSS
CSRF / XSRF
SQL Injection
Privacy

Passwords ¶

Password validation ¶

The only restriction that Elgg places on a password is that it must be at least 6 characters long by default, though this may be changed in /elgg-config/settings.php. Additional criteria can be added by a plugin by registering for the registeruser:validate:password plugin hook.

Password hashing ¶

Passwords are never stored, only salted hashes produced with bcrypt. This is done via the standard password_hash() function. On older systems, the password-compat polyfill is used, but the algorithm is identical.

Elgg installations created before version 1.10 may have residual “legacy” password hashes created using salted MD5. These are migrated to bcrypt as users log in, and will be completely removed when a system is upgraded to Elgg 3.0. In the meantime we’re happy to assist site owners to manually remove these legacy hashes, though it would force those users to reset their passwords.

Password throttling ¶

Elgg has a password throttling mechanism to make dictionary attacks from the outside very difficult. A user is only allowed 5 login attempts over a 5 minute period.

Password resetting ¶

If a user forgets his password, a new random password can be requested. After the request, an email is sent with a unique URL. When the user visits that URL, a new random password is sent to the user through email.

Sessions ¶

Elgg uses PHP’s session handling with custom handlers. Session data is stored in the database. The session cookie contains the session id that links the user to the browser. The user’s metadata is stored in the session including GUID, username, email address. The session’s lifetime is controlled through the server’s PHP configuration.

Session fixation ¶

Elgg protects against session fixation by regenerating the session id when a user logs in.

Session hijacking ¶

Warning

This section is questionable.

Besides protecting against session fixation attacks, Elgg also has a further check to try to defeat session hijacking if the session identifier is compromised. Elgg stores a hash of the browser’s user agent and a site secret as a session fingerprint. The use of the site secret is rather superfluous but checking the user agent might prevent some session hijacking attempts.

Alternative authentication ¶

Note

This section is very hand-wavy

To replace Elgg’s default user authentication system, a plugin would have to replace the default action with its own through register_action(). It would also have to register its own pam handler using register_pam_handler().

Note

The pam_authenticate() function used to call the different modules has a bug related to the importance variable.

HTTPS ¶

Note

You must enable SSL support on your server for any of these techniques to work.

To make the login form submit over https, turn on login-over-ssl from Elgg’s admin panel.

You can also serve your whole site over SSL by simply changing the site URL to include “https” instead of just “http.”

XSS ¶

Filtering is used in Elgg to make XSS attacks more difficult. The purpose of the filtering is to remove Javascript and other dangerous input from users.

Filtering is performed through the function filter_tags(). This function takes in a string and returns a filtered string. It triggers a validate, input plugin hook.

By default Elgg comes with the htmLawed filtering code as a plugin. Developers can drop in any additional or replacement filtering code as a plugin.

The filter_tags() function is called on any user input as long as the input is obtained through a call to get_input(). If for some reason a developer did not want to perform the default filtering on some user input, the get_input() function has a parameter for turning off filtering.

CSRF / XSRF ¶

Elgg generates security tokens to prevent cross-site request forgery. These are embedded in all forms and state-modifying AJAX requests as long as the correct API is used. Read more in the Forms + Actions developer guide.

SQL Injection ¶

Elgg’s API sanitizes all input before issuing DB queries. Read more in the Database design doc.

Privacy ¶

Elgg uses an ACL system to control which users have access to various pieces of content. Read more in the Database design doc.

Loggable¶

Loggable is an interface inherited by any class that wants events relating to its member objects to be saved to the system log. ElggEntity and ElggExtender both inherit Loggable.

Loggable defines several class methods that are used in saving to the default system log, and can be used to define your own (as well as for other purposes):

getSystemLogID() Return a unique identifier for the object for storage in the system log. This is likely to be the object’s GUID
getClassName() Return the class name of the object
getType() Return the object type
getSubtype() Get the object subtype
getObjectFromID($id) For a given ID, return the object associated with it

Database details¶

The default system log is stored in the system_log database table. It contains the following fields:

id - A unique numeric row ID
object_id - The GUID of the entity being acted upon
object_class - The class of the entity being acted upon (eg ElggObject)
object_type - The type of the entity being acted upon (eg object)
object_subtype - The subtype of the entity being acted upon (eg blog)
event - The event being logged (eg create or update)
performed_by_guid - The GUID of the acting entity (the user performing the action)
owner_guid - The GUID of the user which owns the entity being acted upon
access_id - The access restriction associated with this log entry
time_created - The UNIX epoch timestamp of the time the event took place

Contributor Guides¶

Participate in making Elgg even better.

Elgg is a community-driven project. It relies on the support of volunteers to succeed. Here are some ways you can help:

Translations¶

Translations multiply the impact that Elgg can have by making it accessible to a larger percentage of the world.

The community will always be indebted to those of you who work hard to provide high quality translations for Elgg’s UI and docs.

Transifex¶

All translation for the Elgg project is organized through Transifex.

https://www.transifex.com/organization/elgg

Plugin authors are encouraged to coordinate translations via Transifex as well so the whole community can be unified and make it really easy for translators to contribute to any plugin in the Elgg ecosystem.

Reporting Issues¶

Report bugs and features requests to https://github.com/Elgg/Elgg/issues. See below for guidelines.

DISCLAIMERS¶

SECURITY ISSUES SHOULD BE REPORTED TO security @ elgg . org! Please do not post any security issues on github!!
Support requests belong on the community site. Tickets with support requests will be closed.
We cannot make any guarantees as to when your ticket will be resolved.

Bug reports¶

Before submitting a bug report:

Search for an existing ticket on the issue you’re having. Add any extra info there.
Verify the problem is reproducible
- On the latest version of Elgg
- With all third-party plugins disabled

Good bug report checklist:

Expected behavior and actual behavior
Clear steps to reproduce the problem
The version of Elgg you’re running
Browsers affected by this problem

Feature requests¶

Before submitting a feature request:

Check the community site for a plugin that has the features you need.
Consider if you can develop a plugin that does what you need.
Search through the closed tickets to see if someone else suggested the same feature, but got turned down. You’ll need to be able to explain why your suggestion should be considered this time.

Good feature request checklist:

Detailed explanation of the feature
Real-life use-cases
Proposed API

Writing Code¶

Understand Elgg’s standards and processes to get your changes accepted as quickly as possible.

Contents

License agreement
Pull requests
Testing
Coding best practices
Deprecating APIs

License agreement ¶

By submitting a patch you are agreeing to license the code under a GPLv2 license and MIT license.

Pull requests ¶

Pull requests (PRs) are the best way to get code contributed to Elgg core. The core development team uses them even for the most trivial changes.

For new features, submit a feature request or talk to us first and make sure the core team approves of your direction before spending lots of time on code.

Checklists¶

Use these markdown checklists for new PRs on github to ensure high-quality contributions and help everyone understand the status of open PRs.

Bugfix PRs:

- [ ] Commit messages are in the standard format
- [ ] Includes regression test
- [ ] Includes documentation update (if applicable)
- [ ] Is submitted against the correct branch
- [ ] Has LGTM from at least one core developer

Feature PRs:

- [ ] Commit messages are in the standard format
- [ ] Includes tests
- [ ] Includes documentation
- [ ] Is submitted against the correct branch
- [ ] Has LGTM from at least two core developers

Choosing a branch to submit to¶

The following table assumes the latest stable release is 2.1.

Type of change	Branch to submit against
Security fix	Don’t! Email security@elgg.org for guidance.
Bug fix	1.12 (or 2.1 if the 1.12 fix is too complex)
Performance	2.x
Deprecation	2.x
Minor feature	2.x
Major feature	master
Has any breaking change	master

If you’re not sure which branch to submit against, just ask!

The difference between minor and major feature is subjective and up to the core team.

Commit message format¶

We require a particular format to allow releasing more often, and with improved changelogs and source history. Just follow these steps:

Start with the type by selecting the last category which applies from this list:
- docs - only docs are being updated
- chore - this include refactoring, code style changes, adding missing tests, Travis stuff, etc.
- perf - the primary purpose is to improve performance
- fix - this fixes a bug
- deprecate - the change deprecates any part of the API
- feature - this adds a new user-facing or developer feature
- security - the change affects a security issue in any way. Please do not push this commit to any public repo. Instead contact security@elgg.org.
E.g. if your commit refactors to fix a bug, it’s still a “fix”. If that bug is security-related, however, the type must be “security” and you should email security@elgg.org before proceeding. When in doubt, make your best guess and a reviewer will provide guidance.
In parenthesis, add the component, a short string which describes the subsystem being changed.

Some examples: views, i18n, seo, a11y, cache, db, session, router, <plugin_name>.

Add a colon, a space, and a brief summary of the changes, which will appear in the changelog.

No line may exceed 100 characters in length, so keep your summary concise.

Good summary	Bad summary (problem)
page owners see their own owner blocks on pages	bug fix (vague)
bar view no longer dies if ‘foo’ not set	updates views/default/bar.php so bar view no longer… (redundant info)
narrows river layout to fit iPhone	alters the river layout (vague)
elgg_foo() handles arrays for $bar	in elgg_foo() you can now pass an array for $bar and the function will… (move detail to description)
removes link color from comments header in river	fixes db so that… (redundant info)
requires non-empty title when saving pages	can save pages with no title (confusingly summarizes old behavior)

(recommended) Skip a line and add a description of the changes. Include the motivation for making them, any info about back or forward compatibility, and any rationale of why the change had to be done a certain way. Example:

We speed up the Remember Me table migration by using a single INSERT INTO … SELECT query instead of row-by-row. This migration takes place during the upgrade to 1.9.

Unless your change is trivial/obvious, a description is required.
If the commit resolves a GitHub issue, skip a line and add Fixes # followed by the issue number. E.g. Fixes #1234. You can include multiple issues by separating with commas.

GitHub will auto-close the issue when the commit is merged. If you just want to reference an issue, use Refs # instead.

When done, your commit message will have the format:

type(component): summary

Optional body
Details about the solution.
Opportunity to call out as breaking change.

Closes/Fixes/Refs #123, #456, #789

Here is an example of a good commit message:

perf(upgrade): speeds up migrating remember me codes

We speed up the Remember Me table migration by using a single INSERT INTO ... SELECT query instead of row-by-row.
This migration takes place during the upgrade to 1.9.

Fixes #6204

To validate commit messages locally, make sure .scripts/validate_commit_msg.php is executable, and make a copy or symlink to it in the directory .git/hooks/commit-msg.

chmod u+x .scripts/validate_commit_msg.php
ln -s .scripts/validate_commit_msg.php .git/hooks/commit-msg/validate_commit_msg.php

Rewriting commit messages¶

If your PR does not conform to the standard commit message format, we’ll ask you to rewrite it.

To edit just the last commit:

Amend the commit: git commit --amend (git opens the message in a text editor).
Change the message and save/exit the editor.
Force push your branch: git push -f your_remote your_branch (your PR with be updated).
Rename the PR title to match

Otherwise you may need to perform an interactive rebase:

Rebase the last N commits: git rebase -i HEAD~N where N is a number. (Git will open the git-rebase-todo file for editing)
For the commits that need to change, change pick to r (for reword) and save/exit the editor.
Change the commit message(s), save/exit the editor (git will present a file for each commit that needs rewording).
git push -f your_remote your_branch to force push the branch (updating your PR).
Rename the PR title to match

Testing ¶

Elgg has automated tests for both PHP and JavaScript functionality. All new contributions are required to come with appropriate tests.

General guidelines¶

Break tests up by the behaviors you want to test and use names that describe the behavior. E.g.:

Not so good: One big method testAdd().
Better: Methods testAddingZeroChangesNothing and testAddingNegativeNumberSubtracts

Strive for componentized designs that allow testing in isolation, without large dependency graphs or DB access. Injecting dependencies is key here.

PHP Tests¶

PHPUnit¶

Located in engine/tests/phpunit, this is our preferred test suite. It uses no DB access, and has only superficial access to the entities API.

We encourage you to create components that are testable in this suite if possible.
Consider separating storage from your component so at least business logic can be tested here.
Depend on the Elgg\Filesystem\* classes rather than using PHP filesystem functions.

SimpleTest¶

The rest of the files in engine/tests form our integration suite, for anything that needs access to the DB or entity APIs.

Our long-term goals are to minimize these and convert them to PHPUnit

Testing interactions between services¶

Ideally your tests would construct your own isolated object graphs for direct manipulation, but this isn’t always possible.

If your test relies on Elgg’s Service Provider (_elgg_services() returns a Elgg\Di\ServiceProvider), realize that it maintains a singleton instance for most services it hands out, and many services keep their own local references to these services as well.

Due to these local references, replacing services on the SP within a test often will not have the desired effect. Instead, you may need to use functionality baked into the services themselves:

The events and hooks services have methods backup() and restore().
The logger service has methods disable() and enable().

Jasmine Tests¶

Test files must be named *Test.js and should go in either js/tests/ or next to their source files in views/default/**.js. Karma will automatically pick up on new *Test.js files and run those tests.

Test boilerplate¶

define(function(require) {
        var elgg = require('elgg');

        describe("This new test", function() {
                it("fails automatically", function() {
                        expect(true).toBe(false);
                });
        });
});

Running the tests¶

Elgg uses Karma with Jasmine to run JS unit tests.

You will need to have nodejs and npm installed.

First install all the development dependencies:

npm install

Run through the tests just once and then quit:

npm test

You can also run tests continuously during development so they run on each save:

karma start js/tests/karma.conf.js

Debugging JS tests¶

You can run the test suite inside Chrome dev tools:

npm run chrome

This will output a URL like http://localhost:9876/.

Open the URL in Chrome, and click “Debug”.
Open Chrome dev tools and the Console tab.
Reload the page.

If you alter a test you’ll have to quit Karma with Ctrl-c and restart it.

Coding best practices ¶

Make your code easier to read, easier to maintain, and easier to debug. Consistent use of these guidelines means less guess work for developers, which means happier, more productive developers.

General coding¶

Don’t Repeat Yourself¶

If you are copy-pasting code a significant amount of code, consider whether there’s an opportunity to reduce duplication by introducing a function, an additional argument, a view, or a new component class.

E.g. If you find views that are identical except for a single value, refactor into a single view that takes an option.

Note: In a bugfix release, some duplication is preferrable to refactoring. Fix bugs in the simplest way possible and refactor to reduce duplication in the next minor release branch.

Embrace SOLID and GRASP¶

Use these principles for OO design to solve problems using loosely coupled components, and try to make all components and integration code testable.

Whitespace is free¶

Don’t be afraid to use it to separate blocks of code. Use a single space to separate function params and string concatenation.

Variable names¶

Use self-documenting variable names. $group_guids is better than $array.

Avoid double-negatives. Prefer $enable = true to $disable = false.

Interface names¶

Use the pattern Elgg\{Namespace}\{Name}.

Do not include an I prefix or an Interface suffix.

We do not include any prefix or suffix so that we’re encouraged to:

name implementation classes more descriptively (the “default” name is taken).

type-hint on interfaces, because that is the shortest, easiest thing to do.

Name implementations like Elgg\{Namespace}\{Interface}\{Implementation}.

Functions¶

Where possible, have functions/methods return a single type. Use empty values such as array(), "", or 0 to indicate no results.

Be careful where valid return values (like "0") could be interpreted as empty.

Functions not throwing an exception on error should return false upon failure.

Functions returning only boolean should be prefaced with is_ or has_ (eg, elgg_is_logged_in(), elgg_has_access_to_entity()).

Ternary syntax¶

Acceptable only for single-line, non-embedded statements.

Minimize complexity¶

Minimize nested blocks and distinct execution paths through code. Use Return Early to reduce nesting levels and cognitive load when reading code.

Use comments effectively¶

Good comments describe the “why.” Good code describes the “how.” E.g.:

Bad:

// increment $i only when the entity is marked as active.
foreach ($entities as $entity) {
        if ($entity->active) {
                $i++;
        }
}

Good:

// find the next index for inserting a new active entity.
foreach ($entities as $entity) {
        if ($entity->active) {
                $i++;
        }
}

Always include a comment if it’s not obvious that something must be done in a certain way. Other developers looking at the code should be discouraged from refactoring in a way that would break the code.

// Can't use empty()/boolean: "0" is a valid value
if ($str === '') {
    register_error(elgg_echo('foo:string_cannot_be_empty'));
    forward(REFERER);
}

Commit effectively¶

Err on the side of atomic commits which are highly focused on changing one aspect of the system.
Avoid mixing in unrelated changes or extensive whitespace changes. Commits with many changes are scary and make pull requests difficult to review.
Use visual git tools to craft highly precise and readable diffs.

Include tests¶

When at all possible include unit tests for code you add or alter.

Keep bugfixes simple¶

Avoid the temptation to refactor code for a bugfix release. Doing so tends to introduce regressions, breaking functionality in what should be a stable release.

PHP guidelines¶

These are the required coding standards for Elgg core and all bundled plugins. Plugin developers are strongly encouraged to adopt these standards.

Developers should first read the PSR-2 Coding Standard Guide.

Elgg’s standards extend PSR-2, but differ in the following ways:

Indent using one tab character, not spaces.
Opening braces for classes, methods, and functions must go on the same line.
If a line reaches over 100 characters, consider refactoring (e.g. introduce variables).
Compliance with PSR-1 is encouraged, but not strictly required.

Documentation¶

Include PHPDoc comments on functions and classes (all methods; declared properties when appropriate), including types and descriptions of all parameters.
In lists of @param declarations, the beginnings of variable names and descriptions must line up.
Annotate classes, methods, properties, and functions with @access private unless they are intended for public use, are already of limited visibility, or are within a class already marked as private.
Use // or /* */ when commenting.
Use only // comments inside function/method bodies.

Naming¶

Use underscores to separate words in the names of functions, variables, and properties. Method names are camelCase.
Names of functions for public use must begin with elgg_.
All other function names must begin with _elgg_.
Name globals and constants in ALL_CAPS (ACCESS_FRIENDS, $CONFIG).

Miscellaneous¶

For PHP requirements, see composer.json.

Do not use PHP shortcut tags <? or <%. It is OK to use <?= since it is always enabled as of PHP 5.4.

When creating strings with variables:

use double-quoted strings
wrap variables with braces only when necessary.

Bad (hard to read, misuse of quotes and {}s):

echo 'Hello, '.$name."!  How is your {$time_of_day}?";

Good:

echo "Hello, $name!  How is your $time_of_day?";

Remove trailing whitespace at the end of lines. An easy way to do this before you commit is to run php .scripts/fix_style.php from the installation root.

CSS guidelines¶

Use shorthand where possible¶

Bad:

background-color: #333333;
background-image:  url(...);
background-repeat:  repeat-x;
background-position:  left 10px;
padding: 2px 9px 2px 9px;

Good:

background: #333 url(...) repeat-x left 10px;
padding: 2px 9px;

Use hyphens, not underscores¶

Bad:

.example_class {}

Good:

.example-class {}

One property per line¶

Bad:

color: white;font-size: smaller;

Good:

color: white;
font-size: smaller;

Property declarations¶

These should be spaced like so: property: value;

Bad:

color:value;
color :value;
color : value;

Good:

color: value;

Vendor prefixes¶

Group vendor-prefixes for the same property together

Longest vendor-prefixed version first

Always include non-vendor-prefixed version

Put an extra newline between vendor-prefixed groups and other properties

Bad:

-moz-border-radius: 5px;
border: 1px solid #999999;
-webkit-border-radius: 5px;
width: auto;

Good:

border: 1px solid #999999;

-webkit-border-radius: 5px;
-moz-border-radius: 5px;
border-radius: 5px;

width: auto;

Group subproperties¶

Bad:

background-color: white;
color: #0054A7;
background-position: 2px -257px;

Good:

background-color: white;
background-position: 2px -257px;
color: #0054A7;

Javascript guidelines¶

Same formatting standards as PHP apply.

All functions should be in the elgg namespace.

Function expressions should end with a semi-colon.

elgg.ui.toggles = function(event) {
        event.preventDefault();
        $(target).slideToggle('medium');
};

Deprecating APIs ¶

Occasionally functions and classes must be deprecated in favor of newer replacements. Since 3rd party plugin authors rely on a consistent API, backward compatibility must be maintained, but will not be maintained indefinitely as plugin authors are expected to properly update their plugins. In order to maintain backward compatibility, deprecated APIs will follow these guidelines:

Minor version (1.x) that deprecates an API must include a wrapper function/class (or otherwise appropriate means) to maintain backward compatibility, including any bugs in the original function/class. This compatibility layer uses elgg_deprecated_notice('...', '1.11') to log that the function is deprecated.
The next major revision (2.0) removes the compatibility layer. Any use of the deprecated API should be corrected before this.

Adding a Service to Elgg¶

The services guide has general information about using Elgg services.

To add a new service object to Elgg:

Annotate your class as @access private.
Open the class Elgg\Di\ServiceProvider.
Add a @property-read annotation for your service at the top. This allows IDEs and static code analyzers to understand the type of the property.
To the constructor, add code to tell the service provider what to return. See the class Elgg\Di\DiContainer for more information on how Elgg’s DI container works.

At this point your service will be available from the service provider object, but will not yet be accessible to plugins.

Inject your dependencies¶

Design your class constructor to ask for the necessary dependencies rather than creating them or using _elgg_services(). The service provider’s setFactory() method provides access to the service provider instance in your factory method.

Here’s an example of a foo service factory, injecting the config and db services into the constructor:

// in Elgg\Di\ServiceProvider::__construct()

$this->setFactory('foo', function (ServiceProvider $c) {
    return new Elgg\FooService($c->config, $c->db);
});

The full list of internal services can be seen in the @property-read declarations at the top of Elgg\Di\ServiceProvider.

Warning

Avoid performing work in your service constructor, particularly if it requires database queries. Currently PHPUnit tests cannot perform them.

Making a service part of the public API¶

If your service is meant for use by plugin developers:

Make an interface Elgg\Services\<Name> that contains only those methods needed in the public API.
Have your service class implement that interface.
For methods that are in the interface, move the documentation to the interface. You can simply use {@inheritdoc} in the PHPDocs of the concrete class methods.
Document your service in docs/guides/services.rst (this file).
Open the PHPUnit test Elgg\ApplicationTest and add your service key to the $names array in testServices().
Open the class Elgg\Application.
Add @property-read declaration to document your service, but use your interface as the type, not your service class name.
Add your service key to the array in the $public_services property, e.g. 'foo' => true,

Now your service will be available via property access on the Elgg\Application instance:

// using the public foo service
$three = elgg()->foo->add(1, 2);

Note

For examples, see the config service, including the interface Elgg\Services\Config and the concrete implementation Elgg\Config.

Service Life Cycle and Factories¶

By default, services registered on the service provider are “shared”, meaning the service provider will store the created instance for the rest of the request, and serve that same instance to all who request the property.

If you need developers to be able to construct objects that are pre-wired to Elgg services, you may need to add a public factory method to Elgg\Application. Here’s an example that returns a new instance using internal Elgg services:

public function createFoo($bar) {
    $logger = $this->services->logger;
    $db = $this->services->db;
    return new Elgg\Foo($bar, $logger, $db);
}

Writing Documentation¶

New documentation should fit well with the rest of Elgg’s docs.

Contents

Testing docs locally
Follow the existing document organization
Use “Elgg” in a grammatically correct way
Avoid first person pronouns
Eliminate fluff
Prefer absolute dates over relative ones
Do not remind the reader to contribute

Testing docs locally ¶

Elgg has a grunt script that automatically builds the docs, opens them in a browser window, and automatically reloads as you make changes (the reload takes just a few seconds). You need npm and sphinx installed to be able to use these scripts.

cd path/to/elgg/
npm install
grunt

It’s that easy! Grunt will continue running, watching the docs for changes and automatically rebuilding.

Follow the existing document organization ¶

The current breakdown is not necessarily the One True Way to organize docs, but consistency is better than randomness.

intro/*¶

This is everything that brand new users need to know (installation, features, license, etc.)

admin/*¶

Guides for administrators. Task-oriented.

guides/*¶

API guides for plugin developers. Cookbook-style. Example heavy. Code snippet heavy. Broken down by services (actions, i18n, routing, db, etc.). This should only discuss the public API and its behavior, not implementation details or reasoning.

design/*¶

Design docs for people who want to get a better understanding of how/why core is built the way it is. This should discuss internal implementation details of the various services, what tradeoffs were made, and the reasoning behind the final decision. Should be useful for people who want to contribute and for communication b/w core devs.

contribute/*¶

Contributors guides for the various ways people can participate in the project.

appendix/*¶

More detailed/meta/background information about the project (history, roadmap, etc.)

Use “Elgg” in a grammatically correct way ¶

Elgg is not an acronym, so writing it in all caps (ELGG or E-LGG) is incorrect. Please don’t do this.

In English, Elgg does not take an article when used as a noun. Here are some examples to emulate:

“I’m using Elgg to run my website”
“Install Elgg to get your community online”

When used as an adjective, the article applies to the main noun, so you should use one. For example:

“Go to the Elgg community website to get help.”
“I built an Elgg-based network yesterday”

This advice may not apply in languages other than English.

Avoid first person pronouns ¶

Refer to the reader as “you.” Do not include yourself in the normal narrative.

Before:

When we’re done installing Elgg, we’ll look for some plugins!

After:

When you’re done installing Elgg, look for some plugins!

To refer to yourself (avoid this if possible), use your name and write in the third person. This clarifies to future readers/editors whose opinions are being expressed.

Before:

I think the best way to do X is to use Y.

After:

Evan thinks the best way to do X is to use Y.

Eliminate fluff ¶

Before:

If you want to use a third-party javascript library within the Elgg framework, you should take care to call the elgg_register_js function to register it.

After:

To use a third-party javascript library, call elgg_register_js to register it.

Prefer absolute dates over relative ones ¶

It is not easy to tell when a particular sentence or paragraph was written, so relative dates quickly become meaningless. Absolute dates also give the reader a good indication of whether a project has been abandoned, or whether some advice might be out of date.

Before:

Recently the foo was barred. Soon, the baz will be barred too.

After:

Recently (as of September 2013), the foo was barred. The baz is expected to be barred by October 2013.

Do not remind the reader to contribute ¶

Focus on addressing only the topic at hand. Constant solicitation for free work is annoying and makes the project look needy. If people want to contribute to the project, they can visit the contributor guide.

Internationalizing documentation¶

When you change documentation, remember to update the documentation translation templates before you commit:

cd docs/
make gettext

For more information, see http://sphinx-doc.org/latest/intl.html#translating-with-sphinx-intl

Becoming a Financial Supporter¶

All funds raised via the Elgg supporters network go directly into:

Elgg core development
Infrastructure provision (elgg.org, github, etc.)

It is a great way to help with Elgg development!

Benefits¶

For only $50 per year for individuals or $150 per year for organizations, you can get listed as a supporter on our supporters page. Elgg supporters are listed there unless they request not to be.

Supporters are able to put this official logo on their site if they wish:

Disclaimer¶

We operate a no refund policy on supporter subscriptions. If you would like to withdraw your support, go to PayPal and cancel your subscription. You will not be billed the following year.

Being an Elgg Supporter does not give an individual or organization the right to impersonate, trade as or imply they are connected to the Elgg project. They can, however, mention that they support the Elgg project.

If you have any questions about this disclaimer, email info@elgg.org.

We reserve the right to remove or refuse a listing without any prior warning at our complete discretion. There is no refund policy.

If there is no obvious use of Elgg, your site will be linked to with “nofollow” set.

Sign up¶

If you would like to become an Elgg supporter:

read the disclaimer above

on the supporters page, subscribe via PayPal

send an email to info@elgg.org with:

the date you subscribed

your name (and organization name, if applicable)

your website

your Elgg community profile

Once all the details have been received, we will add you to the appropriate list. Thanks for your support!

Release Process Workflow¶

Release a new version of Elgg.

This is the process the core team follows for making a new Elgg release. We have published this information in the spirit of openness, and to streamline onboarding of new team members.

Contents

Requirements
Update composer dependencies
Merge commits up from lower branches
First new stable minor/major release
Prepare the release
Tag the release
Update the website
Make the announcement

Requirements ¶

SSH access to elgg.org
Commit access to http://github.com/Elgg/Elgg
Admin access to https://elgg.org/
Access to Twitter account
Node.js and NPM installed
Sphinx installed (easy_install sphinx && easy_install sphinx-intl)
Transifex client installed (easy_install transifex-client)
Transifex account with access to Elgg project

Update composer dependencies ¶

Since Elgg 2.3, composer.lock is committed to the repository. Therefore, if any of the composer dependencies require an update, run composer update on the corresponding branch and make a pull request with an updated composer.lock file. This will run the test suite and ensure that new dependencies do not break the build.

Merge commits up from lower branches ¶

Determine the LTS branch (currently 1.12). We need to merge any new commits there up through the other branches.

For each branch¶

Check out the branch, make sure it’s up to date, and make a new work branch with the merge. E.g. here we’re merging 1.12 commits into 2.0:

git checkout 2.0
git pull
git checkout -b merge112
git merge 1.12

Note

If already up-to-date (no commits to merge), we can stop here for this branch.

If there are conflicts, resolve them, git add ., and git merge.

Make a PR for the branch and wait for automated tests and approval by other dev(s).

git push -u my_fork merge112

Once merged, we would repeat the process to merge 2.0 commits into 2.1.

First new stable minor/major release ¶

Update the Support policy to include the new minor/major release date and fill in the blanks for the previous release.

Prepare the release ¶

Bring your local git clone up to date.

Merge latest commits up from lowest supported branch.

Visit https://github.com/Elgg/Elgg/compare/<new>...<old> and submit the PR if there is anything that needs to be merged up.

Install the prerequisites:

npm install elgg-conventional-changelog
easy_install sphinx
easy_install sphinx-intl
easy_install transifex-client

Note

On Windows you need to run these command in a console with admin privileges

Run the release.php script. For example, to release 1.12.5:

git checkout 1.12
php .scripts/release.php 1.12.5

This creates a release-1.12.5 branch in your local repo.

Next, manually browse to the /admin/settings/basic page and verify it loads. If it does not, a language file from Transifex may have a PHP syntax error. Fix the error and amend your commit with the new file:

# only necessary if you fixed a language file
git add .
git commit --amend

Next, submit a PR via GitHub for automated testing and approval by another developer:

git push your-remote-fork release-1.12.5

Tag the release ¶

Once approved and merged, tag the release:

git checkout release-${version}
git tag -a ${version} -m'Elgg ${version}'
git push --tags origin release-${version}

Or create a release on GitHub

Goto releases
Click ‘Draft a new release’
Enter the version
Select the correct branch (eg 1.12 for a 1.12.x release, 2.3 for a 2.3.x release, etc)
Set the release title as ‘Elgg {version}’
Paste the CHANGELOG.md part related to this release in the description

Some final administration

Mark GitHub release milestones as completed
Move unresolved tickets in released milestones to later milestones

Update the website ¶

ssh to elgg.org
Clone https://github.com/Elgg/elgg-scripts

Build zip package¶

Use elgg-scripts/build/elgg-starter-project.sh to generate the .zip file. Run without arguments to see usage.

Note

If this is your first time on the server building a release run composer global require "fxp/composer-asset-plugin:^1.2.0". This will make sure you can download bower-assets during the build process.

    # login as user deploy
    sudo -su deploy

# regular release
./elgg-starter-project.sh master 2.0.4 /var/www/www.elgg.org/download/

# MIT release
./elgg-starter-project.sh master 2.0.4-mit /var/www/www.elgg.org/download/

Verify that vendor/elgg/elgg/composer.json in the zip file has the expected version.
If not, make sure GitHub has the release tag, and that the starter project has a compatible elgg/elgg item in the composer requires list.

Building 1.x zip packages¶

Use elgg-scripts/build/build.sh to generate the .zip file. Run without arguments to see usage.

# regular release
./build.sh 1.12.5 1.12.5 /var/www/www.elgg.org/download/

# MIT release
./build.sh 1.12.5 1.12.5-mit /var/www/www.elgg.org/download/

Update elgg.org download page¶

Clone https://github.com/Elgg/community
Add the new version to classes/Elgg/Releases.php
Commit and push the changes
Update the plugin on www.elgg.org

composer update elgg/community

Update elgg.org¶

Clone https://github.com/Elgg/www.elgg.org
Change the required Elgg version in composer.json
Update vendors

composer update

Commit and push the changes
Pull to live site

cd /var/www/www.elgg.org && sudo su deploy && git pull

Update dependencies

composer install --no-dev --prefer-dist --optimize-autoloader

Go to community admin panel
- Flush APC cache
- Run upgrade

Make the announcement ¶

This should be the very last thing you do.

Open https://github.com/Elgg/Elgg/blob/<tag>/CHANGELOG.md and copy the contents for that version
Sign in at https://elgg.org/blog and compose a new blog with a summary
Copy in the CHANGELOG contents, clear formatting, and manually remove the SVG anchors
Add tags release and elgg2.x where x is whatever branch is being released
Tweet from the elgg Twitter account

Appendix¶

Miscellaneous information about the project.

FAQs and Other Troubleshooting¶

Below are some commonly asked questions about Elgg.

Contents

General
Security
Development

General¶

See also

Getting Help

“Plugin cannot start and has been deactivated” or “This plugin is invalid”¶

This error is usually accompanied by more details explaining why the plugin is invalid. This is usually caused by an incorrectly installed plugin.

If you are installing a plugin called “test”, there will be a test directory under mod. In that test directory there needs to be a start.php file: /mod/test/start.php and a manifest.xml file /mod/test/manifest.xml.

If these files do not exist, it could be caused by:

installing a plugin to the wrong directory
creating a directory under /mod that does not contain a plugin
a bad ftp transfer
unzipping a plugin into an extra directory (myplugin.zip unzips to myplugin/myplugin)

If you are on a Unix-based host and the files exist in the correct directory, check the permissions. Elgg must have read access to the files and read + execute access on the directories.

White Page (WSOD)¶

A blank, white page (often called a “white screen of death”) means there is a PHP syntax error. There are a few possible causes of this:

corrupted file - try transfering the code again to your server
a call to a php module that was not loaded - this can happen after you install a plugin that requires a specific module.
bad plugin - not all plugins have been written to the same quality so you should be careful which ones you install.

To find where the error is occurring, change the .htaccess file to display errors to the browser. Set display_errors to 1 and load the same page again. You should see a PHP error in your browser. Change the setting back once you’ve resolved the problem.

Note

If you are using the Developer’s Tools plugin, go to its settings page and make sure you have “Display fatal PHP errors” enabled.

If the white screen is due to a bad plugin, remove the latest plugins that you have installed by deleting their directories and then reload the page.

Note

You can temporarily disable all plugins by creating an empty file at mod/disabled. You can then disable the offending module via the administrator tools panel.

If you are getting a WSOD when performing an action, like logging in or posting a blog, but there are no error messages, it’s most likely caused by non-printable characters in plugin code. Check the plugin for white spaces/new lines characters after finishing php tag (?>) and remove them.

Page not found¶

If you have recently installed your Elgg site, the most likely cause for a page not found error is that mod_rewrite is not setup correctly on your server. There is information in the Install Troubleshooting page on fixing this. The second most likely cause is that your site url in your database is incorrect.

If you’ve been running your site for a while and suddenly start getting page not found errors, you need to ask yourself what has changed. Have you added any plugins? Did you change your server configuration?

To debug a page not found error:

Confirm that the link leading to the missing page is correct. If not, how is that link being generated?
Confirm that the .htaccess rewrite rules are being picked up.

Login token mismatch¶

If you have to log in twice to your site and the error message after the first attempt says there was a token mismatch error, the URL in Elgg’s settings does not match the URL used to access it. The most common cause for this is adding or removing the “www” when accessing the site. For example, www.elgg.org vs elgg.org. This causes a problem with session handling because of the way that web browsers save cookies.

To fix this, you can add rewrite rules. To redirect from www.elgg.org to elgg.org in Apache, the rules might look like:

RewriteCond %{HTTP_HOST} .
RewriteCond %{HTTP_HOST} !^elgg\.org
RewriteRule (.*) http://elgg.org/$1 [R=301,L]

Redirecting from non-www to www could look like this:

RewriteCond %{HTTP_HOST} ^elgg\.org
RewriteRule ^(.*)$ http://www.elgg.org/$1 [R=301,L]

If you don’t know how to configure rewrite rules, ask your host for more information.

Form is missing token or ts fields¶

All Elgg actions require a security token, and this error occurs when that token is missing. This is either a problem with your server configuration or with a 3rd party plugin.

If you experience this on a new installation, make sure that your server is properly configured and your rewrite rules are correct. If you experience this on an upgrade, make sure you have updated your rewrite rules either in .htaccess (Apache) or in the server configuration.

If you are experiencing this, disable all 3rd party plugins and try again. Very old plugins for Elgg don’t use security tokens. If the problem goes away when plugins are disabled, it’s due to a plugin that should be updated by its author.

Maintenance mode¶

To take your site temporarily offline, go to Administration -> Utilities -> Maintenance Mode. Complete the form and hit save to disable your site for everyone except admin users.

Missing email¶

If your users are reporting that validation emails are not showing up, have them check their spam folder. It is possible that the emails coming from your server are being marked as spam. This depends on many factors such as whether your hosting provider has a problem with spammers, how your PHP mail configuration is set up, what mail transport agent your server is using, or your host limiting the number of email that you can send in an hour.

If no one gets email at all, it is quite likely your server is not configured properly for email. Your server needs a program to send email (called a Mail Transfer Agent - MTA) and PHP must be configured to use the MTA.

To quickly check if PHP and an MTA are correctly configured, create a file on your server with the following content:

<?php
$address = "your_email@your_host.com";

$subject = 'Test email.';

$body = 'If you can read this, your email is working.';

echo "Attempting to email $address...<br />";

if (mail($address, $subject, $body)) {
        echo 'SUCCESS!  PHP successfully delivered email to your MTA.  If you don\'t see the email in your inbox in a few minutes, there is a problem with your MTA.';
} else {
        echo 'ERROR!  PHP could not deliver email to your MTA.  Check that your PHP settings are correct for your MTA and your MTA will deliver email.';
}

Be sure to replace “your_email@your_host.com” with your actual email address. Take care to keep quotes around it! When you access this page through your web browser, it will attempt to send a test email. This test will let you know that PHP and your MTA are correctly configured. If it fails–either you get an error or you never receive the email–you will need to do more investigating and possibly contact your service provider.

Fully configuring an MTA and PHP’s email functionality is beyond the scope of this FAQ and you should search the Internet for more resources on this. Some basic information on php parameters can be found on PHP’s site

Server logs¶

Most likely you are using Apache as your web server. Warnings and errors are written to a log by the web server and can be useful for debugging problems. You will commonly see two types of log files: access logs and error logs. Information from PHP and Elgg is written to the server error log.

Linux – The error log is probably in /var/log/httpd or /var/log/apache2.

Windows - It is probably inside your Apache directory.

Mac OS - The error log is probably in /var/log/apache2/error_log

If you are using shared hosting without ssh access, your hosting provider may provide a mechanism for obtaining access to your server logs. You will need to ask them about this.

How does registration work?¶

With a default setup, this is how registration works:

User fills out registration form and submits it
User account is created and disabled until validated
Email is sent to user with a link to validate the account
When a user clicks on the link, the account is validated
The user can now log in

Failures during this process include the user entering an incorrect email address, the validation email being marked as spam, or a user never bothering to validate the account.

User validation¶

By default, all users who self-register must validate their accounts through email. If a user has problems validating an account, you can validate users manually by going to Administration -> Users -> Unvalidated.

You can remove this requirement by deactivating the User Validation by Email plugin.

Note

Removing validation has some consequences: There is no way to know that a user registered with a working email address, and it may leave you system open to spammers.

Manually add user¶

To manually add a user, under the Administer controls go to Users. There you will see a link title “Add new User”. After you fill out the information and submit the form, the new user will receive an email with username and password and a reminder to change the password.

Note

Elgg does not force the user to change the password.

I’m making or just installed a new theme, but graphics or other elements aren’t working¶

Make sure the theme is at the bottom of the plugin list.

Clear your browser cache and reload the page. To lighten the load on the server, Elgg instructs the browser to rarely load the CSS file. A new theme will completely change the CSS file and a refresh should cause the browser to request the CSS file again.

If you’re building or modifying a theme, make sure you have disabled the simple and system caches. This can be done by enabling the Developer Tools plugin, then browsing to Administration -> Develop -> Settings. Once you’re satisfied with the changes, enable the caches or performance will suffer.

Changing profile fields¶

Within the Administration settings of Elgg is a page for replacing the default profile fields. Elgg by default gives the administrator two choices:

Use the default profile fields
Replace the default with a set of custom profile fields

You cannot add new profile fields to the default ones. Adding a new profile field through the replace profile fields option clears the default ones. Before letting in users, it is best to determine what profile fields you want, what field types they should be, and the order they should appear. You cannot change the field type or order or delete fields after they have been created without wiping the entire profile blank.

More flexibility can be gained through plugins. There is at least two plugins on the community site that enable you to have more control over profile fields. The Profile Manager plugin has become quite popular in the Elgg community. It lets you add new profile fields whenever you want, change the order, group profile fields, and add them to registration.

Changing registration¶

The registration process can be changed through a plugin. Everything about registration can be changed: the look and feel, different registration fields, additional validation of the fields, additional steps and so on. These types of changes require some basic knowledge of HTML, CSS, PHP.

Another option is to use the Profile Manager plugin that lets you add fields to both user profiles and the registration form.

Create the plugin skeleton: Plugin skeleton
Changing registration display: Override the account/forms/register view
Changing the registration action handler: You can write your own action to create the user’s account

How do I change PHP settings using .htaccess?¶

You may want to change php settings in your .htaccess file. This is especially true if your hosting provider does not give you access to the server’s php.ini file. The variables could be related to file upload size limits, security, session length, or any number of other php attributes. For examples of how to do this, see the PHP documentation on this.

HTTPS login turned on accidently¶

If you have turned on HTTPS login but do not have SSL configured, you are now locked out of your Elgg install. To turn off this configuration parameter, you will need to edit your database. Use a tool like phpMyAdmin to view your database. Select the config table and delete the row that has the name https_login.

Using a test site¶

It is recommended to always try out new releases or new plugins on a test site before running them on a production site (a site with actual users). The easiest way to do this is to maintain a separate install of Elgg with dummy accounts. When testing changes it is important to use dummy accounts that are not admins to test what your users will see.

A more realistic test is to mirror the content from your production site to your test site. Following the instructions for duplicating a site. Then make sure you prevent emails from being sent to your users. You could write a small plugin that redirects all email to your own account (be aware of plugins that include their own custom email sending code so you’ll have to modify those plugins). After this is done you can view all of the content to make sure the upgrade or new plugin is functioning as desired and is not breaking anything. If this process sounds overwhelming, please stick with running a simple test site.

500 - Internal Server Error¶

What is it?¶

A 500 - Internal Server Error means the web server experienced a problem serving a request.

See also

The Wikipedia page on HTTP status codes

Possible causes¶

Web server configuration: The most common cause for this is an incorrectly configured server. If you edited the .htaccess file and added something incorrect, Apache will send a 500 error.
Permissions on files: It could also be a permissions problem on a file. Apache needs to be able to read Elgg’s files. Using permissions 755 on directories and 644 on files will allow Apache to read the files.

When I upload a photo or change my profile picture I get a white screen¶

Most likely you don’t have the PHP GD library installed or configured properly. You may need assistance from the administrator of your server.

CSS is missing¶

Wrong URL¶

Sometimes people install Elgg so that the base URL is localhost and then try to view the site using a hostname. In this case, the browser won’t be able to load the CSS file. Try viewing the source of the web page and copying the link for the CSS file. Paste that into your browser. If you get a 404 error, it is likely this is your problem. You will need to change the base URL of your site.

Syntax error¶

Elgg stores its CSS as PHP code to provide flexibility and power. If there is a syntax error, the CSS file served to the browser may be blank. Disabling non-bundled plugins is the recommended first step.

Rewrite rules errors¶

A bad .htaccess file could also result in a 404 error when requesting the CSS file. This could happen when doing an upgrade and forgetting to also upgrade .htaccess.

Should I edit the database manually?¶

Warning

No, you should never manually edit the database!

Will editing the database manually break my site?¶

Yes.

Can I add extra fields to tables in the database?¶

(AKA: I don’t understand the Elgg data model so I’m going to add columns. Will you help?)

No, this is a bad idea. Learn the data model and you will see that unless it’s a very specific and highly customized installation, you can do everything you need within Elgg’s current data model.

I want to remove users. Can’t I just delete them from the elgg_users_entity table?¶

No, it will corrupt your database. Delete them through the site.

I want to remove spam. Can’t I just search and delete it from the elgg_objects_entity table?¶

No, it will corrupt your database. Delete it through the site.

Someone on the community site told me to edit the database manually. Should I?¶

Who was it? Is it someone experienced with Elgg, like one of the core developers or a well-known plugin author? Did he or she give you clear and specific instructions on what to edit? If you don’t know who it is, or if you can’t understand or aren’t comfortable following the instructions, do not edit the database manually.

I know PHP and MySQL and have a legitimate reason to edit the database. Is it okay to manually edit the database?¶

Make sure you understand Elgg’s data model and schema first. Make a backup, edit carefully, then test copiously.

Internet Explorer (IE) login problem¶

Canonical URL¶

IE does not like working with sites that use both http://example.org and http://www.example.org. It stores multiple cookies and this causes problems. Best to only use one base URL. For details on how to do this see Login token mismatch error.

Chrome Frame¶

Using the chrome frame within IE can break the login process.

Emails don’t support non-Latin characters¶

In order to support non-Latin characters, (such as Cyrillic or Chinese) Elgg requires multibyte string support to be compiled into PHP.

On many installs (e.g. Debian & Ubuntu) this is turned on by default. If it is not, you need to turn it on (or recompile PHP to include it). To check whether your server supports multibyte strings, check phpinfo.

Session length¶

Session length is controlled by your php configuration. You will first need to locate your php.ini file. In that file will be several session variables. A complete list and what they do can be found in the php manual.

File is missing an owner¶

There are three causes for this error. You could have an entity in your database that has an owner_guid of 0. This should be extremely rare and may only occur if your database/server crashes during a write operation.

The second cause would be an entity where the owner no longer exists. This could occur if a plugin is turned off that was involved in the creation of the entity and then the owner is deleted but the delete operation failed (because the plugin is turned off). If you can figure out entity is causing this, look in your entities table and change the owner_guid to your own and then you can delete the entity through Elgg.

Warning

Reed the section “Should I edit the database manually?”. Be very carefull when editing the database directly. It can break your site. Always make a backup before doing this.

The third cause is a user not having a username. This also indicates a database problem as this should not be possible. If it does occur, you could see this error when viewing a list of users (such as with the Members plugin). To fix, check your users_entity table for users without a username and if so, create a fake a username for that person. You should probably then delete the user through Elgg.

Fixes¶

Database Validator plugin will check your database for these causes and provide an option to fix them. Be sure to backup the database before you try the fix option.

No images¶

If profile images, group images, or other files have stopped working on your site it is likely due to a misconfiguration, especially if you have migrated to a new server.

These are the most common misconfigurations that cause images and other files to stop working.

Wrong path for data directory¶

Make sure the data directory’s path is correct in the Site Administration admin area. It should have a trailing slash.

Wrong permissions on the data directory¶

Check the permissions for the data directory. The data directory should be readable and writeable by the web server user.

Different timezone¶

Note

This only applies to Elgg versions before 1.9

If you migrated servers or upgraded PHP, check that PHP’s timezone settings are the same between the old and the new. If you cannot or don’t want to change the system-wide php.ini file, you can put the following at the top of settings.php:

date_default_timezone_set('MY_TIME_ZONE');

Where MY_TIME_ZONE is a valid PHP timezone.

Migrated installation with new data directory location¶

If you migrated an installation and need to change your data directory path, be sure to update the SQL for the filestore location as documented in the Duplicate Installation instructions.

Deprecation warnings¶

If you are seeing many deprecation warnings that say things like

Deprecated in 1.7: extend_view() was deprecated by elgg_extend_view()!

then you are using a plugin that was written for an older version of Elgg. This means the plugin is using functions that are scheduled to be removed in a future version of Elgg. You can ask the plugin developer if the plugin will be updated or you can update the plugin yourself. If neither of those are likely to happen, you should not use that plugin.

Javascript not working¶

If the user hover menu stops working or you cannot dismiss system messages, that means JavaScript is broken on your site. This usually due to a plugin having bad JavaScript code. You should find the plugin causing the problem and disable it. You can do this be disabling non-bundled plugins one at a time until the problem goes away. Another approach is disabling all non-bundled plugins and then enabling them one by one until the problem occurs again.

Most web browsers will give you a hint as to what is breaking the JavaScript code. They often have a console for JavaScript errors or an advanced mode for displaying errors. Once you see the error message, you may have an easier time locating the problem.

Security¶

Is upgrade.php a security concern?¶

Upgrade.php is a file used to run code and database upgrades. It is in the root of the directory and doesn’t require a logged in account to access. On a fully upgraded site, running the file will only reset the caches and exit, so this is not a security concern.

If you are still concerned, you can either delete, move, or change permissions on the file until you need to upgrade.

Should I delete install.php?¶

This file is used to install Elgg and doesn’t need to be deleted. The file checks if Elgg is already installed and forwards the user to the front page if it is.

Filtering¶

Filtering is used in Elgg to make XSS attacks more difficult. The purpose of the filtering is to remove Javascript and other dangerous input from users.

Filtering is performed through the function filter_tags(). This function takes in a string and returns a filtered string. It triggers a validate, input plugin hook. By default Elgg comes with the htmLawed filtering code as a plugin. Developers can drop in any additional or replacement filtering code as a plugin.

The filter_tags() function is called on any user input as long as the input is obtained through a call to get_input(). If for some reason a developer did not want to perform the default filtering on some user input, the get_input() function has a parameter for turning off filtering.

Development¶

What should I use to edit php code?¶

There are two main options: text editor or integrated development environment (IDE).

Text Editor¶

If you are new to software development or do not have much experience with IDEs, using a text editor will get you up and running the quickest. At a minimum, you will want one that does syntax highlighting to make the code easier to read. If you think you might submit patches to the bug tracker, you will want to make sure that your text editor does not change line endings. If you are using Windows, Notepad++ is a good choice. If you are on a Mac, TextWrangler is a popular choice. You could also give TextMate a try.

Integrated Development Environment¶

An IDE does just what its name implies: it includes a set of tools that you would normally use separately. Most IDEs will include source code control which will allow you to directly commit and update your code from your cvs repository. It may have an FTP client built into it to make the transfer of files to a remote server easier. It will have syntax checking to catch errors before you try to execute the code on a server.

The two most popular free IDEs for PHP developers are Eclipse and NetBeans. Eclipse has two different plugins for working with PHP code: PDT and PHPEclipse.

I don’t like the wording of something in Elgg. How do I change it?¶

The best way to do this is with a plugin.

Create the plugin skeleton¶

Plugin skeleton

Locate the string that you want to change¶

All the strings that a user sees should be in the /languages directory or in a plugin’s languages directory (/mod/<plugin name>/languages). This is done so that it is easy to change what language Elgg uses. For more information on this see the developer documentation on Internationalization .

To find the string use grep or a text editor that provides searching through files to locate the string. (A good text editor for Windows is Notepad++ ) Let’s say we want to change the string “Add friend” to “Make a new friend”. The grep command to find this string would be grep -r "Add friend" *. Using Notepad++ , you would use the “Find in files” command. You would search for the string, set the filter to *.php, set the directory to the base directory of Elgg, and make sure it searches all subdirectories. You might want to set it to be case sensitive also.

You should locate the string “Add friend” in /languages/en.php. You should see something like this in the file:

'friend:add' => "Add friend",

This means every time Elgg sees friend:add it replaces it with “Add friend”. We want to change the definition of friend:add.

Override the string¶

To override this definition, we will add a languages file to the plugin that we built in the first step.

Create a new directory: /mod/<your plugin name>/languages
Create a file in that directory called en.php
Add these lines to that file

<?php

return array(
   'friend:add' => 'Make a new friend',
);

Make sure that you do not have any spaces or newlines before the <?php.

You’re done now and should be able to enable the plugin and see the change. If you are override the language of a plugin, make sure your plugin is loaded after the one you are trying to modify. The loading order is determined in the Tools Administration page of the admin section. As you find more things that you’d like to change, you can keep adding them to this plugin.

How do I find the code that does x?¶

The best way to find the code that does something that you would like to change is to use grep or a similar search tool. If you do not have grep as a part of your operating system, you will want to install a grep tool or use a text-editor/IDE that has good searching in files. Notepad++ is a good choice for Windows users. Eclipse with PHP and NetBeans are good choices for any platform.

String Example¶

Let’s say that you want to find where the Log In box code is located. A string from the Log In box that should be fairly unique is Remember me. Grep for that string. You will find that it is only used in the en.php file in the /languages directory. There it is used to define the Internationalization string user:persistent. Grep for that string now. You will find it in two places: the same en.php language file and in /views/default/forms/login.php. The latter defines the html code that makes up the Log In box.

Action Example¶

Let’s say that you want to find the code that is run when a user clicks on the Save button when arranging widgets on a profile page. View the Profile page for a test user. Use Firebug to drill down through the html of the page until you come to the action of the edit widgets form. You’ll see the url from the base is action/widgets/move.

Grep on widgets/move and two files are returned. One is the JavaScript code for the widgets : /js/lib/ui.widgets.js. The other one, /engine/lib/widgets.php, is where the action is registered using elgg_register_action('widgets/reorder'). You may not be familiar with that function in which case, you should look it up at the API reference. Do a search on the function and it returns the documentation on the function. This tells you that the action is in the default location since a file location was not specified. The default location for actions is /actions so you will find the file at /actions/widgets/move.php.

Debug mode¶

During the installation process you might have noticed a checkbox that controlled whether debug mode was turned on or off. This setting can also be changed on the Site Administration page. Debug mode writes a lot of extra data to your php log. For example, when running in this mode every query to the database is written to your logs. It may be useful for debugging a problem though it can produce an overwhelming amount of data that may not be related to the problem at all. You may want to experiment with this mode to understand what it does, but make sure you run Elgg in normal mode on a production server.

Warning

Because of the amount of data being logged, don’t enable this on a production server as it can fill up the log files really quick.

What goes into the log in debug mode?¶

All database queries
Database query profiling
Page generation time
Number of queries per page
List of plugin language files
Additional errors/warnings compared to normal mode (it’s very rare for these types of errors to be related to any problem that you might be having)

What does the data look like?¶

[07-Mar-2009 14:27:20] Query cache invalidated
[07-Mar-2009 14:27:20] ** GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggentities where guid=1 and ( (1 = 1)  and enabled='yes') results cached
[07-Mar-2009 14:27:20] SELECT guid from elggsites_entity where guid = 1 results cached
[07-Mar-2009 14:27:20] Query cache invalidated
[07-Mar-2009 14:27:20] ** GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggentities where guid=1 and ( (1 = 1)  and enabled='yes') results cached
[07-Mar-2009 14:27:20] ** GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggentities where guid=1 and ( (1 = 1)  and enabled='yes') results returned from cache
[07-Mar-2009 14:27:20] ** Sub part of GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggsites_entity where guid=1 results cached
[07-Mar-2009 14:27:20] Query cache invalidated
[07-Mar-2009 14:27:20] DEBUG: 2009-03-07 14:27:20 (MST): "Undefined index:  user" in file /var/www/elgg/engine/lib/elgglib.php (line 62)
[07-Mar-2009 14:27:20] DEBUG: 2009-03-07 14:27:20 (MST): "Undefined index:  pass" in file /var/www/elgg/engine/lib/elgglib.php (line 62)
[07-Mar-2009 14:27:20] ***************** DB PROFILING ********************
[07-Mar-2009 14:27:20] 1 times: 'SELECT * from elggdatalists'
[07-Mar-2009 14:27:20] 1 times: 'SELECT * from elggentities where guid=1 and (  (access_id in (2) or (owner_guid = -1) or (access_id = 0 and owner_guid = -1)) and enabled='yes')'
...
[07-Mar-2009 14:27:20] 2 times: 'update elggmetadata set access_id = 2 where entity_guid = 1'
[07-Mar-2009 14:27:20] 1 times: 'UPDATE elggentities set owner_guid='0', access_id='2', container_guid='0', time_updated='1236461868' WHERE guid=1'
[07-Mar-2009 14:27:20] 1 times: 'SELECT guid from elggsites_entity where guid = 1'
[07-Mar-2009 14:27:20] 1 times: 'UPDATE elggsites_entity set name='3124/944', description='', url='http://example.org/' where guid=1'
[07-Mar-2009 14:27:20] 1 times: 'UPDATE elggusers_entity set prev_last_action = last_action, last_action = 1236461868 where guid = 2'
[07-Mar-2009 14:27:20] DB Queries for this page: 56
[07-Mar-2009 14:27:20] ***************************************************
[07-Mar-2009 14:27:20] Page /action/admin/site/update_basic generated in 0.36997294426 seconds

What events are triggered on every page load?¶

There are 5 Elgg events that are triggered on every page load:

boot, system
plugins_boot, system
init, system
pagesetup, system (deprecated)
shutdown, system

The boot, system event is triggered before the plugins get loaded. There does not appear to be any difference between the timing of the next two events: plugins_boot, system and init, system so plugins tend to use init, system. This event is triggered in Elgg\Application::bootCore. The pagesetup, system event is thrown the first time elgg_view() is called. Some pages like the default index.php do not call elgg_view() so it is not triggered for them. The shutdown, system event is triggered after the page has been sent to the requester and is handled through the PHP function register_shutdown_function().

There are other events that are triggered by the Elgg core but they happen occasionally (such as when a user logs in).

What variables are reserved by Elgg?¶

$CONFIG
$vars
$autofeed
$_GET['action'] / $_POST['action']
$viewtype

Copy a plugin¶

There are many questions asked about how to copy a plugin. Let’s say you want to copy the blog plugin in order to run one plugin called blog and another called poetry. This is not difficult but it does require a lot of work. You would need to

change the directory name
change the names of every function (having two functions causes PHP to crash)
change the name of every view (so as not to override the views on the original plugin)
change any data model subtypes
change the language file
change anything else that was specific to the original plugin

Note

If you are trying to clone the groups plugin, you will have the additional difficulty that the group plugin does not set a subtype.

General ¶

See also

Getting Help

“Plugin cannot start and has been deactivated” or “This plugin is invalid”¶

This error is usually accompanied by more details explaining why the plugin is invalid. This is usually caused by an incorrectly installed plugin.

If you are installing a plugin called “test”, there will be a test directory under mod. In that test directory there needs to be a start.php file: /mod/test/start.php and a manifest.xml file /mod/test/manifest.xml.

If these files do not exist, it could be caused by:

installing a plugin to the wrong directory
creating a directory under /mod that does not contain a plugin
a bad ftp transfer
unzipping a plugin into an extra directory (myplugin.zip unzips to myplugin/myplugin)

If you are on a Unix-based host and the files exist in the correct directory, check the permissions. Elgg must have read access to the files and read + execute access on the directories.

White Page (WSOD)¶

A blank, white page (often called a “white screen of death”) means there is a PHP syntax error. There are a few possible causes of this:

corrupted file - try transfering the code again to your server
a call to a php module that was not loaded - this can happen after you install a plugin that requires a specific module.
bad plugin - not all plugins have been written to the same quality so you should be careful which ones you install.

To find where the error is occurring, change the .htaccess file to display errors to the browser. Set display_errors to 1 and load the same page again. You should see a PHP error in your browser. Change the setting back once you’ve resolved the problem.

Note

If you are using the Developer’s Tools plugin, go to its settings page and make sure you have “Display fatal PHP errors” enabled.

If the white screen is due to a bad plugin, remove the latest plugins that you have installed by deleting their directories and then reload the page.

Note

You can temporarily disable all plugins by creating an empty file at mod/disabled. You can then disable the offending module via the administrator tools panel.

If you are getting a WSOD when performing an action, like logging in or posting a blog, but there are no error messages, it’s most likely caused by non-printable characters in plugin code. Check the plugin for white spaces/new lines characters after finishing php tag (?>) and remove them.

Page not found ¶

If you have recently installed your Elgg site, the most likely cause for a page not found error is that mod_rewrite is not setup correctly on your server. There is information in the Install Troubleshooting page on fixing this. The second most likely cause is that your site url in your database is incorrect.

If you’ve been running your site for a while and suddenly start getting page not found errors, you need to ask yourself what has changed. Have you added any plugins? Did you change your server configuration?

To debug a page not found error:

Confirm that the link leading to the missing page is correct. If not, how is that link being generated?
Confirm that the .htaccess rewrite rules are being picked up.

Login token mismatch ¶

If you have to log in twice to your site and the error message after the first attempt says there was a token mismatch error, the URL in Elgg’s settings does not match the URL used to access it. The most common cause for this is adding or removing the “www” when accessing the site. For example, www.elgg.org vs elgg.org. This causes a problem with session handling because of the way that web browsers save cookies.

To fix this, you can add rewrite rules. To redirect from www.elgg.org to elgg.org in Apache, the rules might look like:

RewriteCond %{HTTP_HOST} .
RewriteCond %{HTTP_HOST} !^elgg\.org
RewriteRule (.*) http://elgg.org/$1 [R=301,L]

Redirecting from non-www to www could look like this:

RewriteCond %{HTTP_HOST} ^elgg\.org
RewriteRule ^(.*)$ http://www.elgg.org/$1 [R=301,L]

If you don’t know how to configure rewrite rules, ask your host for more information.

Form is missing token or ts fields ¶

All Elgg actions require a security token, and this error occurs when that token is missing. This is either a problem with your server configuration or with a 3rd party plugin.

If you experience this on a new installation, make sure that your server is properly configured and your rewrite rules are correct. If you experience this on an upgrade, make sure you have updated your rewrite rules either in .htaccess (Apache) or in the server configuration.

If you are experiencing this, disable all 3rd party plugins and try again. Very old plugins for Elgg don’t use security tokens. If the problem goes away when plugins are disabled, it’s due to a plugin that should be updated by its author.

Maintenance mode ¶

To take your site temporarily offline, go to Administration -> Utilities -> Maintenance Mode. Complete the form and hit save to disable your site for everyone except admin users.

Missing email ¶

If your users are reporting that validation emails are not showing up, have them check their spam folder. It is possible that the emails coming from your server are being marked as spam. This depends on many factors such as whether your hosting provider has a problem with spammers, how your PHP mail configuration is set up, what mail transport agent your server is using, or your host limiting the number of email that you can send in an hour.

If no one gets email at all, it is quite likely your server is not configured properly for email. Your server needs a program to send email (called a Mail Transfer Agent - MTA) and PHP must be configured to use the MTA.

To quickly check if PHP and an MTA are correctly configured, create a file on your server with the following content:

<?php
$address = "your_email@your_host.com";

$subject = 'Test email.';

$body = 'If you can read this, your email is working.';

echo "Attempting to email $address...<br />";

if (mail($address, $subject, $body)) {
        echo 'SUCCESS!  PHP successfully delivered email to your MTA.  If you don\'t see the email in your inbox in a few minutes, there is a problem with your MTA.';
} else {
        echo 'ERROR!  PHP could not deliver email to your MTA.  Check that your PHP settings are correct for your MTA and your MTA will deliver email.';
}

Be sure to replace “your_email@your_host.com” with your actual email address. Take care to keep quotes around it! When you access this page through your web browser, it will attempt to send a test email. This test will let you know that PHP and your MTA are correctly configured. If it fails–either you get an error or you never receive the email–you will need to do more investigating and possibly contact your service provider.

Fully configuring an MTA and PHP’s email functionality is beyond the scope of this FAQ and you should search the Internet for more resources on this. Some basic information on php parameters can be found on PHP’s site

Server logs ¶

Most likely you are using Apache as your web server. Warnings and errors are written to a log by the web server and can be useful for debugging problems. You will commonly see two types of log files: access logs and error logs. Information from PHP and Elgg is written to the server error log.

Linux – The error log is probably in /var/log/httpd or /var/log/apache2.

Windows - It is probably inside your Apache directory.

Mac OS - The error log is probably in /var/log/apache2/error_log

If you are using shared hosting without ssh access, your hosting provider may provide a mechanism for obtaining access to your server logs. You will need to ask them about this.

How does registration work?¶

With a default setup, this is how registration works:

User fills out registration form and submits it
User account is created and disabled until validated
Email is sent to user with a link to validate the account
When a user clicks on the link, the account is validated
The user can now log in

Failures during this process include the user entering an incorrect email address, the validation email being marked as spam, or a user never bothering to validate the account.

User validation ¶

By default, all users who self-register must validate their accounts through email. If a user has problems validating an account, you can validate users manually by going to Administration -> Users -> Unvalidated.

You can remove this requirement by deactivating the User Validation by Email plugin.

Note

Removing validation has some consequences: There is no way to know that a user registered with a working email address, and it may leave you system open to spammers.

Manually add user ¶

To manually add a user, under the Administer controls go to Users. There you will see a link title “Add new User”. After you fill out the information and submit the form, the new user will receive an email with username and password and a reminder to change the password.

Note

Elgg does not force the user to change the password.

I’m making or just installed a new theme, but graphics or other elements aren’t working ¶

Make sure the theme is at the bottom of the plugin list.

Clear your browser cache and reload the page. To lighten the load on the server, Elgg instructs the browser to rarely load the CSS file. A new theme will completely change the CSS file and a refresh should cause the browser to request the CSS file again.

If you’re building or modifying a theme, make sure you have disabled the simple and system caches. This can be done by enabling the Developer Tools plugin, then browsing to Administration -> Develop -> Settings. Once you’re satisfied with the changes, enable the caches or performance will suffer.

Changing profile fields ¶

Within the Administration settings of Elgg is a page for replacing the default profile fields. Elgg by default gives the administrator two choices:

Use the default profile fields
Replace the default with a set of custom profile fields

You cannot add new profile fields to the default ones. Adding a new profile field through the replace profile fields option clears the default ones. Before letting in users, it is best to determine what profile fields you want, what field types they should be, and the order they should appear. You cannot change the field type or order or delete fields after they have been created without wiping the entire profile blank.

More flexibility can be gained through plugins. There is at least two plugins on the community site that enable you to have more control over profile fields. The Profile Manager plugin has become quite popular in the Elgg community. It lets you add new profile fields whenever you want, change the order, group profile fields, and add them to registration.

Changing registration ¶

The registration process can be changed through a plugin. Everything about registration can be changed: the look and feel, different registration fields, additional validation of the fields, additional steps and so on. These types of changes require some basic knowledge of HTML, CSS, PHP.

Another option is to use the Profile Manager plugin that lets you add fields to both user profiles and the registration form.

Create the plugin skeleton: Plugin skeleton
Changing registration display: Override the account/forms/register view
Changing the registration action handler: You can write your own action to create the user’s account

How do I change PHP settings using .htaccess?¶

You may want to change php settings in your .htaccess file. This is especially true if your hosting provider does not give you access to the server’s php.ini file. The variables could be related to file upload size limits, security, session length, or any number of other php attributes. For examples of how to do this, see the PHP documentation on this.

HTTPS login turned on accidently ¶

If you have turned on HTTPS login but do not have SSL configured, you are now locked out of your Elgg install. To turn off this configuration parameter, you will need to edit your database. Use a tool like phpMyAdmin to view your database. Select the config table and delete the row that has the name https_login.

Using a test site ¶

It is recommended to always try out new releases or new plugins on a test site before running them on a production site (a site with actual users). The easiest way to do this is to maintain a separate install of Elgg with dummy accounts. When testing changes it is important to use dummy accounts that are not admins to test what your users will see.

A more realistic test is to mirror the content from your production site to your test site. Following the instructions for duplicating a site. Then make sure you prevent emails from being sent to your users. You could write a small plugin that redirects all email to your own account (be aware of plugins that include their own custom email sending code so you’ll have to modify those plugins). After this is done you can view all of the content to make sure the upgrade or new plugin is functioning as desired and is not breaking anything. If this process sounds overwhelming, please stick with running a simple test site.

500 - Internal Server Error ¶

What is it?¶

A 500 - Internal Server Error means the web server experienced a problem serving a request.

See also

The Wikipedia page on HTTP status codes

Possible causes¶

Web server configuration: The most common cause for this is an incorrectly configured server. If you edited the .htaccess file and added something incorrect, Apache will send a 500 error.
Permissions on files: It could also be a permissions problem on a file. Apache needs to be able to read Elgg’s files. Using permissions 755 on directories and 644 on files will allow Apache to read the files.

When I upload a photo or change my profile picture I get a white screen ¶

Most likely you don’t have the PHP GD library installed or configured properly. You may need assistance from the administrator of your server.

CSS is missing ¶

Wrong URL¶

Sometimes people install Elgg so that the base URL is localhost and then try to view the site using a hostname. In this case, the browser won’t be able to load the CSS file. Try viewing the source of the web page and copying the link for the CSS file. Paste that into your browser. If you get a 404 error, it is likely this is your problem. You will need to change the base URL of your site.

Syntax error¶

Elgg stores its CSS as PHP code to provide flexibility and power. If there is a syntax error, the CSS file served to the browser may be blank. Disabling non-bundled plugins is the recommended first step.

Rewrite rules errors¶

A bad .htaccess file could also result in a 404 error when requesting the CSS file. This could happen when doing an upgrade and forgetting to also upgrade .htaccess.

Should I edit the database manually?¶

Warning

No, you should never manually edit the database!

Will editing the database manually break my site?¶

Yes.

Can I add extra fields to tables in the database?¶

(AKA: I don’t understand the Elgg data model so I’m going to add columns. Will you help?)

No, this is a bad idea. Learn the data model and you will see that unless it’s a very specific and highly customized installation, you can do everything you need within Elgg’s current data model.

I want to remove users. Can’t I just delete them from the elgg_users_entity table?¶

No, it will corrupt your database. Delete them through the site.

I want to remove spam. Can’t I just search and delete it from the elgg_objects_entity table?¶

No, it will corrupt your database. Delete it through the site.

Someone on the community site told me to edit the database manually. Should I?¶

Who was it? Is it someone experienced with Elgg, like one of the core developers or a well-known plugin author? Did he or she give you clear and specific instructions on what to edit? If you don’t know who it is, or if you can’t understand or aren’t comfortable following the instructions, do not edit the database manually.

I know PHP and MySQL and have a legitimate reason to edit the database. Is it okay to manually edit the database?¶

Make sure you understand Elgg’s data model and schema first. Make a backup, edit carefully, then test copiously.

Internet Explorer (IE) login problem ¶

Canonical URL¶

IE does not like working with sites that use both http://example.org and http://www.example.org. It stores multiple cookies and this causes problems. Best to only use one base URL. For details on how to do this see Login token mismatch error.

Chrome Frame¶

Using the chrome frame within IE can break the login process.

Emails don’t support non-Latin characters ¶

In order to support non-Latin characters, (such as Cyrillic or Chinese) Elgg requires multibyte string support to be compiled into PHP.

On many installs (e.g. Debian & Ubuntu) this is turned on by default. If it is not, you need to turn it on (or recompile PHP to include it). To check whether your server supports multibyte strings, check phpinfo.

Session length ¶

Session length is controlled by your php configuration. You will first need to locate your php.ini file. In that file will be several session variables. A complete list and what they do can be found in the php manual.

File is missing an owner ¶

There are three causes for this error. You could have an entity in your database that has an owner_guid of 0. This should be extremely rare and may only occur if your database/server crashes during a write operation.

The second cause would be an entity where the owner no longer exists. This could occur if a plugin is turned off that was involved in the creation of the entity and then the owner is deleted but the delete operation failed (because the plugin is turned off). If you can figure out entity is causing this, look in your entities table and change the owner_guid to your own and then you can delete the entity through Elgg.

Warning

Reed the section “Should I edit the database manually?”. Be very carefull when editing the database directly. It can break your site. Always make a backup before doing this.

The third cause is a user not having a username. This also indicates a database problem as this should not be possible. If it does occur, you could see this error when viewing a list of users (such as with the Members plugin). To fix, check your users_entity table for users without a username and if so, create a fake a username for that person. You should probably then delete the user through Elgg.

Fixes¶

Database Validator plugin will check your database for these causes and provide an option to fix them. Be sure to backup the database before you try the fix option.

No images ¶

If profile images, group images, or other files have stopped working on your site it is likely due to a misconfiguration, especially if you have migrated to a new server.

These are the most common misconfigurations that cause images and other files to stop working.

Wrong path for data directory¶

Make sure the data directory’s path is correct in the Site Administration admin area. It should have a trailing slash.

Wrong permissions on the data directory¶

Check the permissions for the data directory. The data directory should be readable and writeable by the web server user.

Different timezone¶

Note

This only applies to Elgg versions before 1.9

If you migrated servers or upgraded PHP, check that PHP’s timezone settings are the same between the old and the new. If you cannot or don’t want to change the system-wide php.ini file, you can put the following at the top of settings.php:

date_default_timezone_set('MY_TIME_ZONE');

Where MY_TIME_ZONE is a valid PHP timezone.

Migrated installation with new data directory location¶

If you migrated an installation and need to change your data directory path, be sure to update the SQL for the filestore location as documented in the Duplicate Installation instructions.

Deprecation warnings ¶

If you are seeing many deprecation warnings that say things like

Deprecated in 1.7: extend_view() was deprecated by elgg_extend_view()!

then you are using a plugin that was written for an older version of Elgg. This means the plugin is using functions that are scheduled to be removed in a future version of Elgg. You can ask the plugin developer if the plugin will be updated or you can update the plugin yourself. If neither of those are likely to happen, you should not use that plugin.

Javascript not working ¶

If the user hover menu stops working or you cannot dismiss system messages, that means JavaScript is broken on your site. This usually due to a plugin having bad JavaScript code. You should find the plugin causing the problem and disable it. You can do this be disabling non-bundled plugins one at a time until the problem goes away. Another approach is disabling all non-bundled plugins and then enabling them one by one until the problem occurs again.

Most web browsers will give you a hint as to what is breaking the JavaScript code. They often have a console for JavaScript errors or an advanced mode for displaying errors. Once you see the error message, you may have an easier time locating the problem.

Security ¶

Is upgrade.php a security concern?¶

Upgrade.php is a file used to run code and database upgrades. It is in the root of the directory and doesn’t require a logged in account to access. On a fully upgraded site, running the file will only reset the caches and exit, so this is not a security concern.

If you are still concerned, you can either delete, move, or change permissions on the file until you need to upgrade.

Should I delete install.php?¶

This file is used to install Elgg and doesn’t need to be deleted. The file checks if Elgg is already installed and forwards the user to the front page if it is.

Filtering ¶

Filtering is used in Elgg to make XSS attacks more difficult. The purpose of the filtering is to remove Javascript and other dangerous input from users.

Filtering is performed through the function filter_tags(). This function takes in a string and returns a filtered string. It triggers a validate, input plugin hook. By default Elgg comes with the htmLawed filtering code as a plugin. Developers can drop in any additional or replacement filtering code as a plugin.

The filter_tags() function is called on any user input as long as the input is obtained through a call to get_input(). If for some reason a developer did not want to perform the default filtering on some user input, the get_input() function has a parameter for turning off filtering.

Development ¶

What should I use to edit php code?¶

There are two main options: text editor or integrated development environment (IDE).

Text Editor¶

If you are new to software development or do not have much experience with IDEs, using a text editor will get you up and running the quickest. At a minimum, you will want one that does syntax highlighting to make the code easier to read. If you think you might submit patches to the bug tracker, you will want to make sure that your text editor does not change line endings. If you are using Windows, Notepad++ is a good choice. If you are on a Mac, TextWrangler is a popular choice. You could also give TextMate a try.

Integrated Development Environment¶

An IDE does just what its name implies: it includes a set of tools that you would normally use separately. Most IDEs will include source code control which will allow you to directly commit and update your code from your cvs repository. It may have an FTP client built into it to make the transfer of files to a remote server easier. It will have syntax checking to catch errors before you try to execute the code on a server.

The two most popular free IDEs for PHP developers are Eclipse and NetBeans. Eclipse has two different plugins for working with PHP code: PDT and PHPEclipse.

I don’t like the wording of something in Elgg. How do I change it?¶

The best way to do this is with a plugin.

Create the plugin skeleton¶

Plugin skeleton

Locate the string that you want to change¶

All the strings that a user sees should be in the /languages directory or in a plugin’s languages directory (/mod/<plugin name>/languages). This is done so that it is easy to change what language Elgg uses. For more information on this see the developer documentation on Internationalization .

To find the string use grep or a text editor that provides searching through files to locate the string. (A good text editor for Windows is Notepad++ ) Let’s say we want to change the string “Add friend” to “Make a new friend”. The grep command to find this string would be grep -r "Add friend" *. Using Notepad++ , you would use the “Find in files” command. You would search for the string, set the filter to *.php, set the directory to the base directory of Elgg, and make sure it searches all subdirectories. You might want to set it to be case sensitive also.

You should locate the string “Add friend” in /languages/en.php. You should see something like this in the file:

'friend:add' => "Add friend",

This means every time Elgg sees friend:add it replaces it with “Add friend”. We want to change the definition of friend:add.

Override the string¶

To override this definition, we will add a languages file to the plugin that we built in the first step.

Create a new directory: /mod/<your plugin name>/languages
Create a file in that directory called en.php
Add these lines to that file

<?php

return array(
   'friend:add' => 'Make a new friend',
);

Make sure that you do not have any spaces or newlines before the <?php.

You’re done now and should be able to enable the plugin and see the change. If you are override the language of a plugin, make sure your plugin is loaded after the one you are trying to modify. The loading order is determined in the Tools Administration page of the admin section. As you find more things that you’d like to change, you can keep adding them to this plugin.

How do I find the code that does x?¶

The best way to find the code that does something that you would like to change is to use grep or a similar search tool. If you do not have grep as a part of your operating system, you will want to install a grep tool or use a text-editor/IDE that has good searching in files. Notepad++ is a good choice for Windows users. Eclipse with PHP and NetBeans are good choices for any platform.

String Example¶

Let’s say that you want to find where the Log In box code is located. A string from the Log In box that should be fairly unique is Remember me. Grep for that string. You will find that it is only used in the en.php file in the /languages directory. There it is used to define the Internationalization string user:persistent. Grep for that string now. You will find it in two places: the same en.php language file and in /views/default/forms/login.php. The latter defines the html code that makes up the Log In box.

Action Example¶

Let’s say that you want to find the code that is run when a user clicks on the Save button when arranging widgets on a profile page. View the Profile page for a test user. Use Firebug to drill down through the html of the page until you come to the action of the edit widgets form. You’ll see the url from the base is action/widgets/move.

Grep on widgets/move and two files are returned. One is the JavaScript code for the widgets : /js/lib/ui.widgets.js. The other one, /engine/lib/widgets.php, is where the action is registered using elgg_register_action('widgets/reorder'). You may not be familiar with that function in which case, you should look it up at the API reference. Do a search on the function and it returns the documentation on the function. This tells you that the action is in the default location since a file location was not specified. The default location for actions is /actions so you will find the file at /actions/widgets/move.php.

Debug mode ¶

During the installation process you might have noticed a checkbox that controlled whether debug mode was turned on or off. This setting can also be changed on the Site Administration page. Debug mode writes a lot of extra data to your php log. For example, when running in this mode every query to the database is written to your logs. It may be useful for debugging a problem though it can produce an overwhelming amount of data that may not be related to the problem at all. You may want to experiment with this mode to understand what it does, but make sure you run Elgg in normal mode on a production server.

Warning

Because of the amount of data being logged, don’t enable this on a production server as it can fill up the log files really quick.

What goes into the log in debug mode?¶

All database queries
Database query profiling
Page generation time
Number of queries per page
List of plugin language files
Additional errors/warnings compared to normal mode (it’s very rare for these types of errors to be related to any problem that you might be having)

What does the data look like?¶

[07-Mar-2009 14:27:20] Query cache invalidated
[07-Mar-2009 14:27:20] ** GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggentities where guid=1 and ( (1 = 1)  and enabled='yes') results cached
[07-Mar-2009 14:27:20] SELECT guid from elggsites_entity where guid = 1 results cached
[07-Mar-2009 14:27:20] Query cache invalidated
[07-Mar-2009 14:27:20] ** GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggentities where guid=1 and ( (1 = 1)  and enabled='yes') results cached
[07-Mar-2009 14:27:20] ** GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggentities where guid=1 and ( (1 = 1)  and enabled='yes') results returned from cache
[07-Mar-2009 14:27:20] ** Sub part of GUID:1 loaded from DB
[07-Mar-2009 14:27:20] SELECT * from elggsites_entity where guid=1 results cached
[07-Mar-2009 14:27:20] Query cache invalidated
[07-Mar-2009 14:27:20] DEBUG: 2009-03-07 14:27:20 (MST): "Undefined index:  user" in file /var/www/elgg/engine/lib/elgglib.php (line 62)
[07-Mar-2009 14:27:20] DEBUG: 2009-03-07 14:27:20 (MST): "Undefined index:  pass" in file /var/www/elgg/engine/lib/elgglib.php (line 62)
[07-Mar-2009 14:27:20] ***************** DB PROFILING ********************
[07-Mar-2009 14:27:20] 1 times: 'SELECT * from elggdatalists'
[07-Mar-2009 14:27:20] 1 times: 'SELECT * from elggentities where guid=1 and (  (access_id in (2) or (owner_guid = -1) or (access_id = 0 and owner_guid = -1)) and enabled='yes')'
...
[07-Mar-2009 14:27:20] 2 times: 'update elggmetadata set access_id = 2 where entity_guid = 1'
[07-Mar-2009 14:27:20] 1 times: 'UPDATE elggentities set owner_guid='0', access_id='2', container_guid='0', time_updated='1236461868' WHERE guid=1'
[07-Mar-2009 14:27:20] 1 times: 'SELECT guid from elggsites_entity where guid = 1'
[07-Mar-2009 14:27:20] 1 times: 'UPDATE elggsites_entity set name='3124/944', description='', url='http://example.org/' where guid=1'
[07-Mar-2009 14:27:20] 1 times: 'UPDATE elggusers_entity set prev_last_action = last_action, last_action = 1236461868 where guid = 2'
[07-Mar-2009 14:27:20] DB Queries for this page: 56
[07-Mar-2009 14:27:20] ***************************************************
[07-Mar-2009 14:27:20] Page /action/admin/site/update_basic generated in 0.36997294426 seconds

What events are triggered on every page load?¶

There are 5 Elgg events that are triggered on every page load:

boot, system
plugins_boot, system
init, system
pagesetup, system (deprecated)
shutdown, system

The boot, system event is triggered before the plugins get loaded. There does not appear to be any difference between the timing of the next two events: plugins_boot, system and init, system so plugins tend to use init, system. This event is triggered in Elgg\Application::bootCore. The pagesetup, system event is thrown the first time elgg_view() is called. Some pages like the default index.php do not call elgg_view() so it is not triggered for them. The shutdown, system event is triggered after the page has been sent to the requester and is handled through the PHP function register_shutdown_function().

There are other events that are triggered by the Elgg core but they happen occasionally (such as when a user logs in).

What variables are reserved by Elgg?¶

$CONFIG
$vars
$autofeed
$_GET['action'] / $_POST['action']
$viewtype

Copy a plugin ¶

There are many questions asked about how to copy a plugin. Let’s say you want to copy the blog plugin in order to run one plugin called blog and another called poetry. This is not difficult but it does require a lot of work. You would need to

change the directory name
change the names of every function (having two functions causes PHP to crash)
change the name of every view (so as not to override the views on the original plugin)
change any data model subtypes
change the language file
change anything else that was specific to the original plugin

Note

If you are trying to clone the groups plugin, you will have the additional difficulty that the group plugin does not set a subtype.

Roadmap¶

What direction is the project going? What exciting new features are coming soon?

We do not publish detailed roadmaps, but it’s possible to get a sense for our general direction by utilizing the following resources:

Our feedback and planning group is used to host early discussion about what will be worked on next.
Our Github milestones represent a general direction for the future releases of Elgg. This is the closest thing to a traditional roadmap that we have.
Github pull requests will give you a good idea of what’s currently being developed, but nothing is sure until the PR is actually checked in.
We use the developer blog to post announcements of features that have recently been checked in to our development branch, which gives the surest indication of what features will be available in the next release.

Values¶

We have several overarching goals/values that affect the direction of Elgg. Enhancements generally must promote these values in order to be accepted.

Accessibility¶

Elgg-based sites should be usable by anyone anywhere. That means we’ll always strive to make Elgg:

Device-agnostic – mobile, tablet, desktop, etc. friendly

Language-agnostic – i18n, RTL, etc.

Capability-agnostic – touch, keyboard, screen-reader friendly

Testability¶

We want to make manual testing unnecessary for core developers, plugin authors, and site administrators by promoting and enabling fast, automated testing at every level of the Elgg stack.

We think APIs are broken if they require plugin authors to write untestable code. We know there are a lot of violations of this principle in core currently and are working to fix it.

We look forward to a world where the core developers do not need to do any manual testing to verify the correctness of code contributed to Elgg. Similarly, we envision a world where site administrators can upgrade and install new plugins with confidence that everything works well together.

TODO: other goals/values?

FAQ¶

When will feature X be implemented?¶

We cannot promise when features will get implemented because new features are checked into Elgg only when someone is motivated enough to implement the feature and submit a pull request. The best we can do is tell you to look out for what features existing developers have expressed interest in working on.

The best way to ensure a feature gets implemented is to discuss it with the core team and implement it yourself. See our Contributor Guides guide if you’re interested. We love new contributors!

Do not rely on future enhancements if you’re on the fence as to whether to use Elgg. Evaluate it given the current feature set. Upcoming features will almost certainly not materialize within your timeline.

When is version X.Y.Z going to be released?¶

The next version will be released when the core team feels it’s ready and has time to cut the release. http://github.com/Elgg/Elgg/issues/milestones will give you some rough ideas of timeline.

Release Policy¶

What to expect when upgrading Elgg.

We adhere to semantic versioning.

Follow the blog to stay up to date on the latest releases.

Patch/Bugfix Releases (2.1.x)¶

Every two weeks.

Bugfix releases are made regularly to make sure Elgg stays stable, secure, and bug-free. The higher the third digit, the more tested and stable the release is.

Since bugfix release focus on fixing bugs and not making major changes, themes and plugins should work from bugfix release to bugfix release.

Minor/Feature Releases (2.x.0)¶

Every three months.

Whenever we introduce new features, we’ll bump the middle version number. These releases aren’t as mature as bugfix release, but are considered stable and useable.

We make every effort to be backward compatible in these releases, so plugins should work from minor release to minor release.

However, plugins might need to be updated to make use of the new features.

Major/Breaking Releases (x.0.0)¶

Every year.

Inevitably, improving Elgg requires breaking changes and a new major release is made. These releases are opportunities for the core team to make strategic, breaking changes to the underlying platform. Themes and plugins from older versions are not expected to work without modification on different major releases.

We may remove deprecated APIs, but we will not remove APIs without first deprecating them.

Elgg’s dependencies may be upgraded by their major version or removed entirely. We will not remove any dependences before a major release, but we do not “deprecate” dependencies or issue any warnings before removing them.

Your package, plugin, or app should declare its own dependencies directly so that this does not cause a problem.

Alphas, Betas, and Release Candidates¶

Before major releases (and sometimes before feature releases), the core team will offer a pre-release version of Elgg to get some real-world testing and feedback on the release. These are meant for testing only and should not be used on a live site.

SemVer 2.0 does not define a particular meaning for pre-releases, but we approach alpha, beta, and rc releases with these general guidelines:

An -alpha.X pre-release means that there are still breaking changes planned, but the feature set of the release is frozen. No new features or breaking changes can be proposed for that release.

A -beta.X pre-release means that there are no known breaking changes left to be included, but there are known regressions or critical bugs left to fix.

An -rc.X pre-release means that there are no known regressions or critical bugs left to be fixed. This version could become the final stable version of Elgg if no new blockers are reported.

Support policy¶

As of Elgg 2.0, each minor release receives bug and security fixes only until the next minor release.

Long Term Support Releases¶

Within each major version, the last minor release is designated for long term support (“LTS”) and will receive bug fixes until the 2nd following major version release, and security fixes until the 3rd following major version release.

E.g. 1.12 is the last minor release within 1.x. It will receive bug fixes until 3.0 is released and security fixes until 4.0 is released.

When bugs are found, a good faith effort will be made to patch the LTS release, but not all fixes will be back-ported. E.g. some fixes may depend on new APIs, break backwards compatibility, or require significant refactoring. If a fix risks stability of the LTS branch, it will not be included.

See also

Release Policy

Below is a table outlining the specifics for each release (future dates are tentative):

Version	First stable release	Bug fixes through	Security fixes through
1.12 LTS	July 2015	Until 3.0	Until 4.0
2.0	December 2015	March 2016
2.1	March 2016	June 2016
2.2	June 2016	November 2016
2.3 LTS	November 2016	Until 4.0	Until 5.0
3.0	December 2016
4.0	December 2017

History¶

The name comes from a town in Switzerland. It also means “elk” or “moose” in Danish.

Elgg’s initial funding was by a company called Curverider Ltd, which was started by David Tosh and Ben Werdmuller. In 2010, Curverider was acquired by Thematic Networks and control of the open-source project was turned over to The Elgg Foundation. Today, Elgg is a community-driven open source project and has a variety of contributors and supporters.