Plugin skeleton

The following is the standard for plugin structure in Elgg as of Elgg 1.8. Plugins written for Elgg 1.7 and down are strongly encouraged to use this structure as well, though some of the benefits are not as apparent as when used in 1.8.

Example Structure

The following is an example of a plugin with standard structure. For further explanation of this structure, see the details in the following sections. Your plugin may not need all the files listed

The following files for plugin example would go in /mod/example/

actions/
    example/
        action.php
    other_action.php
classes/
    ExampleClass.php
graphics/
    example.png
js/
    example.js
languages/
    en.php
lib/
    example.php
pages/
    example/
        all.php
        owner.php
vendors/
    example_3rd_party_lib/
views/
    default/
        example/
            css.php
        forms/
            example/
                action.php
                other_action.php
        js/
            example.php
        object/
             example.php
            example/
                context1.php
                context2.php
        plugins/
            example/
                settings.php
                usersettings.php
        widgets/
            example_widget/
                content.php
                edit.php
activate.php
deactivate.php
CHANGES.txt
COPYRIGHT.txt
INSTALL.txt
LICENSE.txt
manifest.xml
README.txt
start.php

Required Files

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

Therefore the following is the minimally compliant structure:

mod/example/
    start.php
    manifest.xml

Actions

Plugins should place scripts for actions an actions/ directory, and furthermore should use the name of the action to determine the location within that directory.

For example, the action my/example/action would go in my_plugin/actions/my/example/action.php. This makes it very obvious which script is associated with which action.

Similarly, the body of the form that submits to this action should be located in forms/my/example/action.php. Not only does this make the connection b/w action handler, form code, and action name obvious, but it allows you to use the new (as of Elgg 1.8) elgg_view_form() function easily.

Text Files

Plugins may provide various *.txt as additional documentation for the plugin. These files must be in Markdown syntax and will generate links on the plugin management sections.

README.txt
should provide additional information about the plugin of an unspecified nature
COPYRIGHT.txt
If included, must provide an explanation of the plugin’s copyright, besides what is included in manifest.xml
LICENSE.txt
If included, must provide the text of the license that the plugin is released under.
INSTALL.txt
If included, must provide additional instructions for installing the plugin if the process is sufficiently complicated (e.g. if it requires installing third party libraries on the host machine, or requires acquiring an API key from a third party).
CHANGES.txt
If included, must provide a list of changes for their plugin, grouped by version number, with the most recent version at the top.

Plugins may include additional *.txt files besides these, but no interface is given for reading them.

Pages

Plugins should put page-generating scripts in a pages/ directory inside their plugin root. Furthermore, plugins should put page-generating scripts under a directory named for their handler. For example, the script for page yoursite.com/my_handler/view/1234 should be located at mod/my_plugin/pages/my_handler/view.php.

In the past, these scripts were included directly in the plugin root. Plugins should not do this anymore, and if any core plugins are found to do this, that is a bug if not present solely for the sake of backwards compatibility.

Note

The reason we encourage this structure is

  • To form a logical relationship between urls and scripts, so that people examining the code can have an idea of what it does just by examining the structure.
  • To clean up the root plugin directory, which historically has quickly gotten cluttered with the page handling scripts.

Classes

All classes that your plugin defines should be included in a classes/ directory. This directory has special meaning to Elgg. Classes placed in this directory are autoloaded on demand, and do not need to be included explicitly.

Warning

Each file must have exactly one class defined inside it. The file name must match the name of the one class that the file defines (except for the ”.php” suffix).

Note

Files with a ”.class.php” extension will not be recognized by Elgg.

Vendors

Included third-party libraries of any kind should be included in the vendors/ folder in the plugin root. Though this folder has no special significance to the Elgg engine, this has historically been the location where Elgg core stores its third-party libraries, so we encourage the same format for the sake of consistency and familiarity.

Lib

Procedural code defined by your plugin should be placed in the lib/ directory. Though this folder has no special significance to the Elgg engine, this has historically been the location where Elgg core stores its procedural code, so we encourage the same format for the sake of consistency and familiarity.

Views

In order to override core views, a plugin’s views must be placed in a views/. This directory has special meaning to Elgg as views defined here automatically override Elgg core’s version of those views. For more info, see Views.

Javascript

Javascript that will be included on every page should be put in the plugin/js view and your plugin should extend js/elgg with this view. Javascript that does not need to be included on every page should be put in a static javascript file under the js/ directory. For more information on Javascript in Elgg, see JavaScript.

activate.php and deactivate.php

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