How Symfony transformed Drupal

As Symfony is based on OOP and modern PHP standards (PSR, namespace, autoloading...), Drupal has abandoned its old procedural model for clearer, more organized classes. This makes Drupal much more flexible, testable and maintainable. The core of Drupal has become more modular and interoperable.

The routing system is much more powerful and easier to read. It allows you to link a URL to a controller while managing permissions and response format.

Example of a route :

my_module.index:

path: '/my-path

defaults:

_controller: '\Drupal\my_module\Controller\MyController::index'

requirements:

_permission: 'access content' 
 

Symfony works with service containers. Classes depend on each other throughdependency injection.

Services can then be injected into controllers, forms, plugins and so on. This makes the code much more modular and testable.

Functionalities no longer have to be stored in Drupal's ancestral.module file, but can be organized in services. Any Design Pattern can be used as required.

Dependency injection makes code more maintainable, modular and extensible. Code is easier for developers to read, since dependencies are visible right from the constructor. You don't have to worry about object lifecycles, the Symfony container takes care of that.

Example of instantiating a service in a file: my_module.services.yml

services:

my_module.my_service:

class: Drupal\my_module\Service\MyService

arguments: ['@logger.factory']

Example of service implementation in a class:

public function __construct(

public readonly MyService $myService

) {}

Thanks to Symfony, Drupal has rethought its entity management system using certain Doctrine components. Drupal doesn't useORM because its entities are dynamic and not rigidly mapped to classes/tables, and some entities are not in databases but rather YAML configurations. However, it has its own mini-ORM using EntityAPI. Drupal therefore offers a version inspired by the modern ideas of Doctrine, but with its own twist:

$node = $this->entityTypeManager

->getStorage('node')->load(42);

$title = $node->getTitle();

Or query via EntityQuery :

$nids = $this->entityTypeManager

->getQuery

->condition('status', 1)

->execute();