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<?php
namespace Drupal\rest\EventSubscriber;
use Drupal\Core\Cache\CacheableMetadata;
use Drupal\Core\Cache\CacheableResponse;
use Drupal\Core\Cache\CacheableResponseInterface;
use Drupal\Core\Render\RendererInterface;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\rest\ResourceResponseInterface;
use Drupal\serialization\Normalizer\CacheableNormalizerInterface;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\Event\ResponseEvent;
use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Serializer\SerializerInterface;
/**
* Response subscriber that serializes and removes ResourceResponses' data.
*/
class ResourceResponseSubscriber implements EventSubscriberInterface {
/**
* The serializer.
*
* @var \Symfony\Component\Serializer\SerializerInterface
*/
protected $serializer;
/**
* The renderer.
*
* @var \Drupal\Core\Render\RendererInterface
*/
protected $renderer;
/**
* The current route match.
*
* @var \Drupal\Core\Routing\RouteMatchInterface
*/
protected $routeMatch;
/**
* Constructs a ResourceResponseSubscriber object.
*
* @param \Symfony\Component\Serializer\SerializerInterface $serializer
* The serializer.
* @param \Drupal\Core\Render\RendererInterface $renderer
* The renderer.
* @param \Drupal\Core\Routing\RouteMatchInterface $route_match
* The current route match.
*/
public function __construct(SerializerInterface $serializer, RendererInterface $renderer, RouteMatchInterface $route_match) {
$this->serializer = $serializer;
$this->renderer = $renderer;
$this->routeMatch = $route_match;
}
/**
* Serializes ResourceResponse responses' data, and removes that data.
*
* @param \Symfony\Component\HttpKernel\Event\ResponseEvent $event
* The event to process.
*/
public function onResponse(ResponseEvent $event) {
$response = $event->getResponse();
if (!$response instanceof ResourceResponseInterface) {
return;
}
$request = $event->getRequest();
$format = $this->getResponseFormat($this->routeMatch, $request);
$this->renderResponseBody($request, $response, $this->serializer, $format);
$event->setResponse($this->flattenResponse($response));
}
/**
* Determines the format to respond in.
*
* Respects the requested format if one is specified. However, it is common to
* forget to specify a response format in case of a POST or PATCH. Rather than
* simply throwing an error, we apply the robustness principle: when POSTing
* or PATCHing using a certain format, you probably expect a response in that
* same format.
*
* @param \Drupal\Core\Routing\RouteMatchInterface $route_match
* The current route match.
* @param \Symfony\Component\HttpFoundation\Request $request
* The current request.
*
* @return string
* The response format.
*/
public function getResponseFormat(RouteMatchInterface $route_match, Request $request) {
$route = $route_match->getRouteObject();
$acceptable_response_formats = $route->hasRequirement('_format') ? explode('|', $route->getRequirement('_format')) : [];
$acceptable_request_formats = $route->hasRequirement('_content_type_format') ? explode('|', $route->getRequirement('_content_type_format')) : [];
$acceptable_formats = $request->isMethodCacheable() ? $acceptable_response_formats : $acceptable_request_formats;
$requested_format = $request->getRequestFormat();
$content_type_format = $request->getContentTypeFormat();
// If an acceptable response format is requested, then use that. Otherwise,
// including and particularly when the client forgot to specify a response
// format, then use heuristics to select the format that is most likely
// expected.
if (in_array($requested_format, $acceptable_response_formats, TRUE)) {
return $requested_format;
}
// If a request body is present, then use the format corresponding to the
// request body's Content-Type for the response, if it's an acceptable
// format for the request.
if (!empty($request->getContent()) && in_array($content_type_format, $acceptable_request_formats, TRUE)) {
return $content_type_format;
}
// Otherwise, use the first acceptable format.
if (!empty($acceptable_formats)) {
return $acceptable_formats[0];
}
// Sometimes, there are no acceptable formats.
return NULL;
}
/**
* Renders a resource response body.
*
* During serialization, encoders and normalizers are able to explicitly
* bubble cacheability metadata via the 'cacheability' key-value pair in the
* received context. This bubbled cacheability metadata will be applied to the
* the response.
*
* @param \Symfony\Component\HttpFoundation\Request $request
* The request object.
* @param \Drupal\rest\ResourceResponseInterface $response
* The response from the REST resource.
* @param \Symfony\Component\Serializer\SerializerInterface $serializer
* The serializer to use.
* @param string|null $format
* The response format, or NULL in case the response does not need a format.
*
* @todo Add test coverage for language negotiation contexts in
* https://www.drupal.org/node/2135829.
*/
protected function renderResponseBody(Request $request, ResourceResponseInterface $response, SerializerInterface $serializer, $format) {
$data = $response->getResponseData();
// If there is data to send, serialize and set it as the response body.
if ($data !== NULL) {
$serialization_context = [
'request' => $request,
CacheableNormalizerInterface::SERIALIZATION_CONTEXT_CACHEABILITY => new CacheableMetadata(),
];
$output = $serializer->serialize($data, $format, $serialization_context);
if ($response instanceof CacheableResponseInterface) {
$response->addCacheableDependency($serialization_context[CacheableNormalizerInterface::SERIALIZATION_CONTEXT_CACHEABILITY]);
}
$response->setContent($output);
$response->headers->set('Content-Type', $request->getMimeType($format));
}
}
/**
* Flattens a fully rendered resource response.
*
* Ensures that complex data structures in ResourceResponse::getResponseData()
* are not serialized. Not doing this means that caching this response object
* requires unserializing the PHP data when reading this response object from
* cache, which can be very costly, and is unnecessary.
*
* @param \Drupal\rest\ResourceResponseInterface $response
* A fully rendered resource response.
*
* @return \Drupal\Core\Cache\CacheableResponse|\Symfony\Component\HttpFoundation\Response
* The flattened response.
*/
protected function flattenResponse(ResourceResponseInterface $response) {
$final_response = ($response instanceof CacheableResponseInterface) ? new CacheableResponse() : new Response();
$final_response->setContent($response->getContent());
$final_response->setStatusCode($response->getStatusCode());
$final_response->setProtocolVersion($response->getProtocolVersion());
if ($response->getCharset()) {
$final_response->setCharset($response->getCharset());
}
$final_response->headers = clone $response->headers;
if ($final_response instanceof CacheableResponseInterface) {
$final_response->addCacheableDependency($response->getCacheableMetadata());
}
return $final_response;
}
/**
* {@inheritdoc}
*/
public static function getSubscribedEvents(): array {
// Run before
// \Drupal\dynamic_page_cache\EventSubscriber\DynamicPageCacheSubscriber
// (priority 7), so that Dynamic Page Cache can cache flattened responses.
$events[KernelEvents::RESPONSE][] = ['onResponse', 128];
return $events;
}
}
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