[Drupal] Service dependency injection in a plugin type class

The code

<?php

namespace Drupal\my_module\Controller;

use Drupal\Core\Controller\ControllerBase;
use Drupal\Core\Entity\EntityTypeManager;    // Example service class to load and use
use Drupal\Core\Entity\Query\QueryFactory;   // Another example service class to load and use
use Symfony\Component\DependencyInjection\ContainerInterface;

class MyModuleController extends ControllerBase {

  /**
   * @var QueryFactory
   */
  protected $queryFactory;

  /**
   * @var EntityTypeManager
   */
  protected $entityTypeManager;

  public static function create(ContainerInterface $container) {
    // Get your services here.
    return new static(
        $container->get('entity.query'), $container->get('entity_type.manager')
    );
  }

  public function __construct(QueryFactory $query_factory, EntityTypeManager $entity_type_manager) {
    // Reference your services here for future use
    $this->queryFactory = $query_factory;
    $this->entityTypeManager = $entity_type_manager;
  }

  public function content() {
    // Do Controller stuff...
    $ids = $this->queryFactory->get('node')->condition('type', 'article')->pager(15)->execute();
    $entities = $this->entityTypeManager->getStorage('node')->loadMultiple($ids);

    // etc...
  }

}

<?php

namespace Drupal\my_module\Controller;

use Drupal\Core\Controller\ControllerBase;

use Drupal\Core\Entity\EntityTypeManager; // Example service class to load and use

use Drupal\Core\Entity\Query\QueryFactory; // Another example service class to load and use

use Symfony\Component\DependencyInjection\ContainerInterface;

class MyModuleController extends ControllerBase {

/**

* @var QueryFactory

protected $queryFactory;

/**

* @var EntityTypeManager

protected $entityTypeManager;

public static function create(ContainerInterface $container) {

// Get your services here.

return new static(

$container->get('entity.query'), $container->get('entity_type.manager')

);

}

public function __construct(QueryFactory $query_factory, EntityTypeManager $entity_type_manager) {

// Reference your services here for future use

$this->queryFactory = $query_factory;

$this->entityTypeManager = $entity_type_manager;

}

public function content() {

// Do Controller stuff...

$ids = $this->queryFactory->get('node')->condition('type', 'article')->pager(15)->execute();

$entities = $this->entityTypeManager->getStorage('node')->loadMultiple($ids);

// etc...

}

Additional Information

Unlike service type class service dependency injection, there may be no need to implement an interface to be able to load the needed services, such as extending from ControllerBase. So if you are extending from a class which already has the dependency injection implementation, you can just override the create and __construct methods. Don’t forget to call parent methods if needed.
Think of the create method as the model used by the __construct of your class.
The create signature needs to respect the one of the implemented interface (use your IDE to check against the original declaration).
Originally made and tested on Drupal 8.2.x.
A convenient list of core services can be found here: https://api.drupal.org/api/drupal/core%21core.services.yml/8.2.x (don’t forget to select the Drupal version if you are not on 8.2.x).
Some classes such as ones extending BlockBase will need to implement interfaces to access this pattern:

class SomeCustomBlock extends BlockBase implements ContainerFactoryPluginInterface { ... }

1

class SomeCustomBlock extends BlockBase implements ContainerFactoryPluginInterface { ... }

The code

Additional Information

Published by Dakwamine