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Object Oriented Programming
PHP Namespaces
Dependency Injection
Symfony
Annotations
Plugins
Services
Other resources
Creating modules
Getting Started - Background & Prerequisites
Naming and placing your Drupal module
Let Drupal know about your module with an .info.yml file
Include default configuration in your Drupal module
Defining and using your own configuration in Drupal
Create a custom page
Creating custom blocks
Creating custom field types, widgets, and formatters
Subscribe to and dispatch events
Building a Views display style plugin for Drupal
Adding stylesheets (CSS) and JavaScript (JS) to a Drupal module
Step by step tutorial "Lorem Ipsum"
Step by step tutorial: Hello World
Understanding hooks
Getting Started - Background & Prerequisites
Last
updated
on
8 November 2024
This documentation is
deprecated
Drupal leverages a number of advanced PHP language features and sophisticated 3rd party libraries in order to present external developers with the most advanced API of any CMS available. While experienced Drupal 7 developers may see some significant changes, much of the basic structure will remain familiar.
If any of the material presented while going through the D8 module developer's walk-through is new to you, then the material below may help. However, a comprehensive knowledge is not necessary to proceed to the
D8 module walkthrough
Object Oriented Programming
OOP, while initially daunting, is now well established as a best practice.
For a general overview of PHP best practices, read through
phptherightway.com
. Drupal doesn't make use of all the different tools and techniques documented there but it does serve as a great introduction to PHP and the language's many features.
Brush up on your OOP knowledge by reading the official PHP documentation on
Classes and Objects
as well as some of these other good primers:
PHP OOP in Full Effect
Object-oriented programming
(on Wikipedia)
Object-Oriented PHP for Beginners
(at tuts+)
Object Oriented Concepts
(at tutorialspoint.com)
Object Oriented Programming in PHP
(at youtube.com)
Foundations of Programming: Object Oriented Design
(at lynda.com)
Must know 12 PHP OOP concepts
OOP Track on SymfonyCasts
(formerly KNP university)
Drupal 8 also makes use of some common design patterns and you'll want to make sure you have a basic understanding of these:
The Factory Pattern
, and
Late static bindings
Software design pattern
(on Wikipedia)
Foundations of Programming: Design Patterns
(at lynda.com)
@todo: add more links to documentation about the patterns we use ...
PHP Namespaces
If you're unfamiliar with the concept of namespacing in PHP, try some of these articles:
How to use PHP namespaces
PHP: Namespaces
a video on PHP namespaces
PHP Namespaces Explained
(by Dayle Rees)
Namespacing in PHP
(at tuts+)
In most cases, the Drupal code is namespaced based on the module that code belongs to.
Example: namespace for the block.module
namespace Drupal\block;
@todo: explain why sometimes it's Drupal\ and sometimes it's Drupal\\[Controller|Form|Plugin|etc.] and how I should know which to use ...
Read more about the
Drupal namespace standards
. More on
PSR-4 usage in Drupal here
. Correctly configured coding software should be able to pick up on PHP namespaces and provide help and autocompletions.
Dependency Injection
Although dependency injection is really just another OOP design pattern, we call it out here because Drupal 8 makes heavy use of the concept and it is important to have a baseline understanding in order to access and make use of many of the core APIs.
Read up on
dependency injection on PHP the right way
, as well as the additional articles linked on that page. Especially
this article
because Drupal makes heavy use of the Symfony service container referenced.
See also:
Services and dependency injection in Drupal 8
Dependency injection
(on Wikipedia)
Symfony
Symfony is a PHP framework that Drupal borrows from in order to reduce code duplication across various PHP projects. Much of the code that Drupal 8 uses to handle routing, sessions and the services container, amongst other things, is borrowed from Symfony 2 (and as Drupal 8 developed, moved into Symfony 3). If you want to know more about why this decision was made, check out
this presentation
by core-committer alexpott for some background.
Check out the
Symfony book
and brush up on your Symfony knowledge. While not all of it is required to understand Drupal, knowing how Symfony works will make you both a better Drupal developer and a better PHP developer. You might also be interested in the
Symfony Glossary
Check out core/composer.lock to see the Symfony libraries. As of Drupal
8.6.15
, these are the Symfony PHP and closely related libraries:
...
"symfony/class-loader": "~3.4.0",
"symfony/console": "~3.4.0",
"symfony/dependency-injection": "~3.4.26",
"symfony/event-dispatcher": "~3.4.0",
"symfony/http-foundation": "~3.4.26",
"symfony/http-kernel": "~3.4.14",
"symfony/routing": "~3.4.0",
"symfony/serializer": "~3.4.0",
"symfony/translation": "~3.4.0",
"symfony/validator": "~3.4.0",
"symfony/process": "~3.4.0",
"symfony/polyfill-iconv": "^1.0",
"symfony/yaml": "~3.4.5",
"twig/twig": "^1.38.2",
"doctrine/common": "^2.5",
"doctrine/annotations": "^1.2",
...
Annotations
Drupal 8 makes use of PHP annotations – @docblock comments added to your code using a special syntax – for plugin discovery and to provide additional context/meta-data for code that's being executed. Annotations are read using the
Doctrine annotation parser (v.1.6.)
then turned into information that Drupal can use to better understand what your code is doing.
Read more about the use of
annotations for plugin discovery
See a list of
all the different annotation types
in Drupal 8.
See also:
PHPDoc
(on Wikipedia)
Plugins
Plugins provide small pieces of functionality in such a way that they can be easily swapped out for another plugin. Plugins that perform similar functionality are of the same plugin type. For example, 'Field widget' is a plugin type, and each different field widget (eg. text field, textarea, date, etc.) is implemented with a plugin.
Read more about the
Plugin API in Drupal 8
Services
In Drupal 8 speak, a service is any object managed by the services container. The concept of services was introduced to decouple reusable functionality and makes these services pluggable and replaceable by registering them with a service container of
dependency injection
, which they heavily relate to.
See also:
Service Container For Drupal Geeks
(on YouTube)
Other resources
Below is a list of additional resources to help ensure that you hit the ground running with Drupal 8.
Tags
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