Issue #2775479 by Wim Leers, klausi, dawehner: Try to remove the "map HEAD to...

Issue #2775479 by Wim Leers, klausi, dawehner: Try to remove the "map HEAD to GET" logic in \Drupal\rest\RequestHandler::handle()

core/modules/rest/src/RequestHandler.php

@@ -61,22 +61,20 @@ public static function create(ContainerInterface $container) {
    *   The response object.
    */
   public function handle(RouteMatchInterface $route_match, Request $request) {
-    $method = strtolower($request->getMethod());
-
     // Symfony is built to transparently map HEAD requests to a GET request. In
     // the case of the REST module's RequestHandler though, we essentially have
     // our own light-weight routing system on top of the Drupal/symfony routing
-    // system. So, we have to do the same as what the UrlMatcher does: map HEAD
-    // requests to the logic for GET. This also guarantees response headers for
-    // HEAD requests are identical to those for GET requests, because we just
-    // return a GET response. Response::prepare() will transform it to a HEAD
-    // response at the very last moment.
+    // system. So, we have to respect the decision that the routing system made:
+    // we look not at the request method, but at the route's method. All REST
+    // routes are guaranteed to have _method set.
+    // Response::prepare() will transform it to a HEAD response at the very last
+    // moment.
     // @see https://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9.4
     // @see \Symfony\Component\Routing\Matcher\UrlMatcher::matchCollection()
     // @see \Symfony\Component\HttpFoundation\Response::prepare()
-    if ($method === 'head') {
-      $method = 'get';
-    }
+    $method = strtolower($route_match->getRouteObject()->getMethods()[0]);
+    assert(count($route_match->getRouteObject()->getMethods()) === 1);
+
 
     $resource_config_id = $route_match->getRouteObject()->getDefault('_rest_resource_config');
     /** @var \Drupal\rest\RestResourceConfigInterface $resource_config */

core/modules/rest/tests/src/Kernel/RequestHandlerTest.php

@@ -49,7 +49,7 @@ public function setUp() {
    */
   public function testHandle() {
     $request = new Request();
-    $route_match = new RouteMatch('test', new Route('/rest/test', ['_rest_resource_config' => 'restplugin'], ['_format' => 'json']));
+    $route_match = new RouteMatch('test', (new Route('/rest/test', ['_rest_resource_config' => 'restplugin'], ['_format' => 'json']))->setMethods(['GET']));
 
     $resource = $this->prophesize(StubRequestHandlerResourcePlugin::class);
     $resource->get(NULL, $request)
@@ -76,7 +76,7 @@ public function testHandle() {
     $this->assertEquals($response, $handler_response);
 
     // We will call the patch method this time.
-    $route_match = new RouteMatch('test', new Route('/rest/test', ['_rest_resource_config' => 'restplugin'], ['_content_type_format' => 'json']));
+    $route_match = new RouteMatch('test', (new Route('/rest/test', ['_rest_resource_config' => 'restplugin'], ['_content_type_format' => 'json']))->setMethods(['PATCH']));
     $request->setMethod('PATCH');
     $response = new ResourceResponse([]);
     $resource->patch(NULL, $request)