aleph1.co.uk Git - yaffs-website/blob - web/core/lib/Drupal/Core/EventSubscriber/ClientErrorResponseSubscriber.php

   1 <?php
   2
   3 namespace Drupal\Core\EventSubscriber;
   4
   5 use Drupal\Core\Cache\CacheableMetadata;
   6 use Drupal\Core\Cache\CacheableResponseInterface;
   7 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
   8 use Symfony\Component\HttpKernel\KernelEvents;
   9 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
  10
  11 /**
  12  * Response subscriber to set the '4xx-response' cache tag on 4xx responses.
  13  */
  14 class ClientErrorResponseSubscriber implements EventSubscriberInterface {
  15
  16   /**
  17    * Sets the '4xx-response' cache tag on 4xx responses.
  18    *
  19    * @param \Symfony\Component\HttpKernel\Event\FilterResponseEvent $event
  20    *   The event to process.
  21    */
  22   public function onRespond(FilterResponseEvent $event) {
  23     if (!$event->isMasterRequest()) {
  24       return;
  25     }
  26
  27     $response = $event->getResponse();
  28     if (!$response instanceof CacheableResponseInterface) {
  29       return;
  30     }
  31
  32     if ($response->isClientError()) {
  33       $http_4xx_response_cacheability = new CacheableMetadata();
  34       $http_4xx_response_cacheability->setCacheTags(['4xx-response']);
  35       $response->addCacheableDependency($http_4xx_response_cacheability);
  36     }
  37   }
  38
  39   /**
  40    * {@inheritdoc}
  41    */
  42   public static function getSubscribedEvents() {
  43     // Priority 10, so that it runs before FinishResponseSubscriber, which will
  44     // expose the cacheability metadata in the form of headers.
  45     $events[KernelEvents::RESPONSE][] = ['onRespond', 10];
  46     return $events;
  47   }
  48
  49 }