Creating automatic Node titles with custom Events in Drupal 10

Introduction

In this tutorial, we'll learn how to create an automatic node title using a custom event and event subscriber in Drupal 9. This can be helpful when you want to generate titles for specific content types programmatically.

Prerequisites

• Basic understanding of Drupal 9 module development
• A running Drupal 9 instance for testing

Step 1: Create a custom module

First, create a custom module if you haven't already. For this example, let's name the module auto_title.

Step 2: Create a custom event

Inside the src/Event folder of your custom module, create a new PHP file called AutoTitleEvent.php. Add the following code to define your custom event:

namespace Drupal\auto_title\Event;

use Drupal\node\NodeInterface;
use Symfony\Contracts\EventDispatcher\Event;

class AutoTitleEvent extends Event {

  const AUTO_TITLE = 'auto_title.auto_title_event';

  protected $node;

  public function __construct(NodeInterface $node) {
    $this->node = $node;
  }

  public function getNode() {
    return $this->node;
  }

}

Step 3: Create an event subscriber

In the src/EventSubscriber folder of your custom module, create a new PHP file called AutoTitleSubscriber.php. Add the following code to define the event subscriber:

namespace Drupal\auto_title\EventSubscriber;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Drupal\auto_title\Event\AutoTitleEvent;

class AutoTitleSubscriber implements EventSubscriberInterface {

  public static function getSubscribedEvents() {
    $events[AutoTitleEvent::AUTO_TITLE][] = 'onAutoTitle';
    return $events;
  }

  public function onAutoTitle(AutoTitleEvent $event) {
    $node = $event->getNode();
    if ($node->bundle() == 'your_content_type') {
      // Generate your custom title here.
      $title = 'Custom Title - ' . date('Y-m-d H:i:s');

      // Set the node title.
      $node->setTitle($title);
    }
  }
}

Replace 'your_content_type' with the machine name of the content type you want to target.

Step 4: Register the event subscriber

In your custom module's auto_title.services.yml file, register the event subscriber:

services:
  auto_title.auto_title_subscriber:
    class: Drupal\auto_title\EventSubscriber\AutoTitleSubscriber
    tags:
      - { name: event_subscriber }

Step 5: Dispatch the custom event

Implement hook_entity_presave in your custom module's .module file and dispatch the custom event:

use Drupal\auto_title\Event\AutoTitleEvent;

/**
 * Implements hook_entity_presave().
 */
function auto_title_entity_presave(Drupal\Core\Entity\EntityInterface $entity) {
  if ($entity->getEntityTypeId() == 'node') {
    $event_dispatcher = \Drupal::service('event_dispatcher');
    $auto_title_event = new AutoTitleEvent($entity);
    $event_dispatcher->dispatch($auto_title_event, AutoTitleEvent::AUTO_TITLE);
  }
}

Step 6: Clear the cache

After making changes to your custom module, clear the cache to ensure your changes take effect:

drush cr

By following these steps, you've created a custom event and an event subscriber to automatically set the node