Development:Developer documentation

This Developer section of Moodle Docs is aimed at developers who contribute to the Moodle code, plugins, themes, and so on.

If you manage a Moodle site, Administrator documentation may suit your needs better.
If you teach using Moodle, try Teacher documentation.

Note: New developer documentation pages should be added to the Development namespace by typing Development: before the new page name i.e. [[Development:New page name]]. If you are a developer, you probably want to change your preferences to include the Development namespace in searches.

A page may be added to the Developer category by adding the template {{CategoryDeveloper}} to the bottom of the page. - If required, you can use [[Category:Developer|Sort key]] to provide a sort key other than the default page name.

How Moodle development works

The overview of the Moodle development process explains how Moodle development occurs and how people become Moodle developers. Current plans are listed on the Roadmap.

You can also enrol in one of the Moodle Developer Courses.

Guidelines

The following guidelines are crucial reading for anyone wanting to contribute to the Moodle code base:

Coding guidelines have to be followed by all Moodle developers
Moodle architecture gives an overview of how the Moodle code works
Development:Process explains how changes are incorporated into Moodle
Tracker explains the Moodle Tracker for keeping track of bugs, issues, feature requests etc
Working with the Community explains how to engage with the dev community and discuss changes
Unit tests explains how to run the unit tests, and how to write new test cases.
Profiling PHP how to analyse your code to find out why it is slow.
Development:Fast portable SQL shows SQL techniques that are fast, efficient, and known to work on all supported DBs.
Development:Development hints and tips a (developing) list of general wisdom to help with your Moodle projects.

Documentation for core components

This section is for documentation of specific components of the existing core Moodle code. Discussion of components that are under discussion or in development can be found in the developer notes or on the roadmap.

The documents below give a general overview. For detailed function-by-function documentation, see the phpDocumentor documentation that is automatically generated from the comments in the code.

And don't forget that the most up-to-date and detailed description of how the code works is the code itself, and you can browse the code online using PHPXref.

Core components

Database abstraction layer @ v1.7
Roles and Capabilities system @ v1.7 for controlling who can do what
Forms library @ v1.8 for creating accessible and secure HTML forms that let users edit things
File API @ v2.0 for managing files stored by Moodle
The database schema
What happens when you require config.php
lib/moodlelib.php
lib/weblib.php for outputting stuff

Core libraries with a more specific uses

Authentication API
Cookieless Sessions
Email processing
Environment checking before install, check the user's server to ensure Moodle will work there.
Groups system
Gradebook
Moodle Network
Question engine
Stats package
Migration to UTF-8 @ v1.6
YUI JavaScript library - YUI was selected as the official AJAX library for Moodle.
lib/graphlib
Admin settings

Modules included in the standard distribution

How you can contribute

Make a new plugin

The M in Moodle stands for modular, and the easiest, most maintainable way to add new functionality to Moodle is by using one of the many plugin APIs. There are many types of plugin you can write:

Activity modules, see also Development:NEWMODULE Documentation (work in progress)
- and Sub-Plugins (2.0 Onwards)
Admin reports
Assignment types
Authentication plugins
Blocks
Content editors (2.0 onwards)
Course formats
Course reports
Course importers (2.0 onwards)
Database fields
Database presets
Enrolment plugins
Filters
Gradebook report
Gradebook export
Gradebook import
Message senders (2.0 onwards)
Mnet services
Plagiarism detection plugins (2.0 onwards)
Portfolio plugins (2.0 onwards)
Question types
Question import/export formats
Quiz reports
Repository plugins (2.0 onwards)
Resource types
Search engine adapters
Themes which are different in Moodle 2.0, and earlier versions.
User profile fields
Web services (2.0 onwards)
Workshop allocators (2.0 onwards)
Workshop forms (2.0 onwards)
Workshop evaluators (2.0 onwards)

General information that applies to all types of plugins

Please see the Guidelines for contributed code for an overview of how to contribute to the Moodle code.

Sometimes it is not possible to write a proper plugin for what you want to do, in which case you may have to resort to using the local customisations hook.

Change core code

Some types of change can only be made by editing the core Moodle code. Such changes are much harder to maintain than plugins. If you want your core change to be considered for inclusion in the official Moodle release, you need to create an issue in the tracker, and attach your change as a patch. It is also a good idea to discuss your ideas in the forums first. See Development:Overview#Major_Development for more details.

Ways to contribute that do not involve PHP programming

Plans for the future

Ideas for and details of planned future features of Moodle are initially discussed on the forums in the Using Moodle course at moodle.org. That developer discussions are intermixed with user discussions in the same forums may seem strange at first but is one of the reasons for the success of Moodle. It is important that both end-users and developers discuss the future features together.

Once ideas begin to crystallize on the forums they can be summarized in this wiki, either as part of the roadmap or in the form of developer notes. These pages then form the basis for further discussion in the forums.

Resources

Developer FAQ - frequently asked questions, especially useful for newcomers to Moodle
Finding your way into the Moodle code - also aimed at newcomers
Moodle tracker - bug reports, feature requests and other tracked issues
- Firefox tracker search - How to setup a firefox quicksearch to easily navigate to moodle bugs
- Firefox Search Plugins - Find tracked issues even more easily
Unmerged files - changes on the stable branch in CVS that have not been merged to HEAD
Browse the code online:
- the code with a complete change history from CVS
- the code, with links generated by PHPXref
Moodle PHP doc reference - compiled nightly from the comment attached to each class and function in the code.
Database Schema - for recent releases
Development news and discussion section of Using Moodle course
- especially the General developer forum
- cool tricks you can use in the moodle.org forums

Tools

Some tools people use when working on Moodle code:

IDEs

Setting up NetBeans for Moodle development - NetBeans for PHP is a great out-of-the-box editor.
Setting up Eclipse for Moodle development - Eclipse is a great editor to use for php development, if you can work out how to set it up.
Setting up Vim for Moodle development
Aptana Studio 2

Browser add-ons

Firebug, see Firebug for details.
Web developer extension
ViewSourceWith - The main goal is to view page source with external applications, but you can do a lot of other things as well.

Miscellaneous

Ctags - Using a tags file to navigate code
W3C HTML validator - Moodle has built in support to make using it easier.
Windows Installer - Windows Installer documentation for developer.

Documentation