Drupal Event Subscribers
Example (Best Practice)
// src/EventSubscriber/MyEventSubscriber.php
namespace Drupal\my_module\EventSubscriber;
use Drupal\Core\Session\AccountProxyInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\Event\RequestEvent;
use Symfony\Component\HttpKernel\KernelEvents;
final class MyEventSubscriber implements EventSubscriberInterface {
public function __construct(
private readonly AccountProxyInterface $currentUser,
) {}
public static function getSubscribedEvents(): array {
return [
// Note: Higher priority runs earlier. Default is 0.
KernelEvents::REQUEST => ['onRequest', 100],
];
}
public function onRequest(RequestEvent $event): void {
if (!$event->isMainRequest()) {
return;
}
if (!$this->currentUser->isAuthenticated()) {
return;
}
// Example: log or modify behavior for authenticated users.
}
}
Register in services.yml
services:
my_module.my_event_subscriber:
class: Drupal\my_module\EventSubscriber\MyEventSubscriber
arguments: ['@current_user']
tags:
- { name: event_subscriber }
Common Events
| Event | Constant | When |
|---|
| Request | KernelEvents::REQUEST | Every request |
| Response | KernelEvents::RESPONSE | Before response sent |
| Terminate | KernelEvents::TERMINATE | After response sent |
| Exception | KernelEvents::EXCEPTION | On uncaught exception |
Generate with Drush
drush generate event-subscriber --answers='{
"module": "my_module",
"class": "MyEventSubscriber",
"event": "kernel.request"
}'
