Chris@0: <?php
Chris@0: 
Chris@0: namespace Drupal\Core\EventSubscriber;
Chris@0: 
Chris@0: use Drupal\Core\Ajax\AjaxResponse;
Chris@0: use Drupal\Core\Cache\CacheableDependencyInterface;
Chris@0: use Drupal\Core\Cache\CacheableResponseInterface;
Chris@0: use Drupal\Core\Render\AttachmentsInterface;
Chris@0: use Drupal\Core\Render\BubbleableMetadata;
Chris@0: use Drupal\Core\Render\RenderContext;
Chris@0: use Drupal\Core\Render\RendererInterface;
Chris@0: use Symfony\Component\EventDispatcher\EventSubscriberInterface;
Chris@17: use Symfony\Component\HttpKernel\Controller\ArgumentResolverInterface;
Chris@0: use Symfony\Component\HttpKernel\Event\FilterControllerEvent;
Chris@0: use Symfony\Component\HttpKernel\KernelEvents;
Chris@0: 
Chris@0: /**
Chris@0:  * Subscriber that wraps controllers, to handle early rendering.
Chris@0:  *
Chris@0:  * When controllers call drupal_render() (RendererInterface::render()) outside
Chris@0:  * of a render context, we call that "early rendering". Controllers should
Chris@0:  * return only render arrays, but we cannot prevent controllers from doing early
Chris@0:  * rendering. The problem with early rendering is that the bubbleable metadata
Chris@0:  * (cacheability & attachments) are lost.
Chris@0:  *
Chris@0:  * This can lead to broken pages (missing assets), stale pages (missing cache
Chris@0:  * tags causing a page not to be invalidated) or even security problems (missing
Chris@0:  * cache contexts causing a cached page not to be varied sufficiently).
Chris@0:  *
Chris@0:  * This event subscriber wraps all controller executions in a closure that sets
Chris@0:  * up a render context. Consequently, any early rendering will have their
Chris@0:  * bubbleable metadata (assets & cacheability) stored on that render context.
Chris@0:  *
Chris@0:  * If the render context is empty, then the controller either did not do any
Chris@0:  * rendering at all, or used the RendererInterface::renderRoot() or
Chris@0:  * ::renderPlain() methods. In that case, no bubbleable metadata is lost.
Chris@0:  *
Chris@0:  * If the render context is not empty, then the controller did use
Chris@0:  * drupal_render(), and bubbleable metadata was collected. This bubbleable
Chris@0:  * metadata is then merged onto the render array.
Chris@0:  *
Chris@0:  * In other words: this just exists to ease the transition to Drupal 8: it
Chris@0:  * allows controllers that return render arrays (the majority) and
Chris@0:  * \Drupal\Core\Ajax\AjaxResponse\AjaxResponse objects (a sizable minority that
Chris@0:  * often involve a fair amount of rendering) to still do early rendering. But
Chris@0:  * controllers that return any other kind of response are already expected to
Chris@0:  * do the right thing, so if early rendering is detected in such a case, an
Chris@0:  * exception is thrown.
Chris@0:  *
Chris@0:  * @see \Drupal\Core\Render\RendererInterface
Chris@0:  * @see \Drupal\Core\Render\Renderer
Chris@0:  *
Chris@0:  * @todo Remove in Drupal 9.0.0, by disallowing early rendering.
Chris@0:  */
Chris@0: class EarlyRenderingControllerWrapperSubscriber implements EventSubscriberInterface {
Chris@0: 
Chris@0:   /**
Chris@17:    * The argument resolver.
Chris@0:    *
Chris@17:    * @var \Symfony\Component\HttpKernel\Controller\ArgumentResolverInterface
Chris@0:    */
Chris@17:   protected $argumentResolver;
Chris@0: 
Chris@0:   /**
Chris@0:    * The renderer.
Chris@0:    *
Chris@0:    * @var \Drupal\Core\Render\RendererInterface
Chris@0:    */
Chris@0:   protected $renderer;
Chris@0: 
Chris@0:   /**
Chris@0:    * Constructs a new EarlyRenderingControllerWrapperSubscriber instance.
Chris@0:    *
Chris@17:    * @param \Symfony\Component\HttpKernel\Controller\ArgumentResolverInterface $argument_resolver
Chris@17:    *   The argument resolver.
Chris@0:    * @param \Drupal\Core\Render\RendererInterface $renderer
Chris@0:    *   The renderer.
Chris@0:    */
Chris@17:   public function __construct(ArgumentResolverInterface $argument_resolver, RendererInterface $renderer) {
Chris@17:     $this->argumentResolver = $argument_resolver;
Chris@0:     $this->renderer = $renderer;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Ensures bubbleable metadata from early rendering is not lost.
Chris@0:    *
Chris@0:    * @param \Symfony\Component\HttpKernel\Event\FilterControllerEvent $event
Chris@0:    *   The controller event.
Chris@0:    */
Chris@0:   public function onController(FilterControllerEvent $event) {
Chris@0:     $controller = $event->getController();
Chris@0: 
Chris@0:     // See \Symfony\Component\HttpKernel\HttpKernel::handleRaw().
Chris@17:     $arguments = $this->argumentResolver->getArguments($event->getRequest(), $controller);
Chris@0: 
Chris@0:     $event->setController(function () use ($controller, $arguments) {
Chris@0:       return $this->wrapControllerExecutionInRenderContext($controller, $arguments);
Chris@0:     });
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * Wraps a controller execution in a render context.
Chris@0:    *
Chris@0:    * @param callable $controller
Chris@0:    *   The controller to execute.
Chris@0:    * @param array $arguments
Chris@0:    *   The arguments to pass to the controller.
Chris@0:    *
Chris@0:    * @return mixed
Chris@0:    *   The return value of the controller.
Chris@0:    *
Chris@0:    * @throws \LogicException
Chris@0:    *   When early rendering has occurred in a controller that returned a
Chris@0:    *   Response or domain object that cares about attachments or cacheability.
Chris@0:    *
Chris@0:    * @see \Symfony\Component\HttpKernel\HttpKernel::handleRaw()
Chris@0:    */
Chris@0:   protected function wrapControllerExecutionInRenderContext($controller, array $arguments) {
Chris@0:     $context = new RenderContext();
Chris@0: 
Chris@0:     $response = $this->renderer->executeInRenderContext($context, function () use ($controller, $arguments) {
Chris@0:       // Now call the actual controller, just like HttpKernel does.
Chris@0:       return call_user_func_array($controller, $arguments);
Chris@0:     });
Chris@0: 
Chris@0:     // If early rendering happened, i.e. if code in the controller called
Chris@0:     // drupal_render() outside of a render context, then the bubbleable metadata
Chris@0:     // for that is stored in the current render context.
Chris@0:     if (!$context->isEmpty()) {
Chris@0:       /** @var \Drupal\Core\Render\BubbleableMetadata $early_rendering_bubbleable_metadata */
Chris@0:       $early_rendering_bubbleable_metadata = $context->pop();
Chris@0: 
Chris@0:       // If a render array or AjaxResponse is returned by the controller, merge
Chris@0:       // the "lost" bubbleable metadata.
Chris@0:       if (is_array($response)) {
Chris@0:         BubbleableMetadata::createFromRenderArray($response)
Chris@0:           ->merge($early_rendering_bubbleable_metadata)
Chris@0:           ->applyTo($response);
Chris@0:       }
Chris@0:       elseif ($response instanceof AjaxResponse) {
Chris@0:         $response->addAttachments($early_rendering_bubbleable_metadata->getAttachments());
Chris@0:         // @todo Make AjaxResponse cacheable in
Chris@0:         //   https://www.drupal.org/node/956186. Meanwhile, allow contrib
Chris@0:         //   subclasses to be.
Chris@0:         if ($response instanceof CacheableResponseInterface) {
Chris@0:           $response->addCacheableDependency($early_rendering_bubbleable_metadata);
Chris@0:         }
Chris@0:       }
Chris@0:       // If a non-Ajax Response or domain object is returned and it cares about
Chris@0:       // attachments or cacheability, then throw an exception: early rendering
Chris@0:       // is not permitted in that case. It is the developer's responsibility
Chris@0:       // to not use early rendering.
Chris@0:       elseif ($response instanceof AttachmentsInterface || $response instanceof CacheableResponseInterface || $response instanceof CacheableDependencyInterface) {
Chris@0:         throw new \LogicException(sprintf('The controller result claims to be providing relevant cache metadata, but leaked metadata was detected. Please ensure you are not rendering content too early. Returned object class: %s.', get_class($response)));
Chris@0:       }
Chris@0:       else {
Chris@0:         // A Response or domain object is returned that does not care about
Chris@0:         // attachments nor cacheability; for instance, a RedirectResponse. It is
Chris@0:         // safe to discard any early rendering metadata.
Chris@0:       }
Chris@0:     }
Chris@0: 
Chris@0:     return $response;
Chris@0:   }
Chris@0: 
Chris@0:   /**
Chris@0:    * {@inheritdoc}
Chris@0:    */
Chris@0:   public static function getSubscribedEvents() {
Chris@0:     $events[KernelEvents::CONTROLLER][] = ['onController'];
Chris@0: 
Chris@0:     return $events;
Chris@0:   }
Chris@0: 
Chris@0: }