Meta link headers (#81)

* Adding rel=alternate link headers for metadata REST endpoints

* Missed a few spots in tests still bootstrapping their own REST config.

islandora.services.yml

@@ -20,12 +20,12 @@ services:
       - { name: event_subscriber }
   islandora.media_link_header_subscriber:
     class: Drupal\islandora\EventSubscriber\MediaLinkHeaderSubscriber
-    arguments: ['@entity_field.manager', '@current_route_match', '@entity_type.manager']
+    arguments: ['@entity_type.manager', '@entity_field.manager', '@current_route_match', '@access_manager', '@current_user']
     tags:
       - { name: event_subscriber }
   islandora.node_link_header_subscriber:
     class: Drupal\islandora\EventSubscriber\NodeLinkHeaderSubscriber
-    arguments: ['@entity_field.manager', '@current_route_match']
+    arguments: ['@entity_type.manager', '@entity_field.manager', '@current_route_match', '@access_manager', '@current_user']
     tags:
       - { name: event_subscriber }
   islandora.versioncounter:

src/EventSubscriber/LinkHeaderSubscriber.php

@@ -2,8 +2,13 @@
 
 namespace Drupal\islandora\EventSubscriber;
 
+use Drupal\Core\Access\AccessManagerInterface;
 use Drupal\Core\Entity\EntityFieldManager;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityTypeManager;
 use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\Url;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
@@ -16,6 +21,13 @@ use Symfony\Component\HttpKernel\KernelEvents;
  */
 abstract class LinkHeaderSubscriber implements EventSubscriberInterface {
 
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManager
+   */
+  protected $entityTypeManager;
+
   /**
    * The entity field manager.
    *
@@ -33,17 +45,45 @@ abstract class LinkHeaderSubscriber implements EventSubscriberInterface {
   /**
    * Constructor.
    *
+   * The access manager.
+   *
+   * @var \Drupal\Core\Access\AccessManagerInterface
+   */
+  protected $accessManager;
+
+  /**
+   * Current user.
+   *
+   * @var \Drupal\Core\Session\AccountInterface
+   */
+  protected $account;
+
+  /**
+   * Constructor.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManager $entity_type_manager
+   *   The entity type manager.
    * @param \Drupal\Core\Entity\EntityFieldManager $entity_field_manager
    *   The entity field manager.
    * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
    *   The route match object.
+   * @param \Drupal\Core\Access\AccessManagerInterface $access_manager
+   *   The access manager.
+   * @param \Drupal\Core\Session\AccountInterface $account
+   *   The current user.
    */
   public function __construct(
+    EntityTypeManager $entity_type_manager,
     EntityFieldManager $entity_field_manager,
-    RouteMatchInterface $route_match
+    RouteMatchInterface $route_match,
+    AccessManagerInterface $access_manager,
+    AccountInterface $account
   ) {
+    $this->entityTypeManager = $entity_type_manager;
     $this->entityFieldManager = $entity_field_manager;
     $this->routeMatch = $route_match;
+    $this->accessManager = $access_manager;
+    $this->account = $account;
   }
 
   /**
@@ -113,6 +153,109 @@ abstract class LinkHeaderSubscriber implements EventSubscriberInterface {
     return $object;
   }
 
+  /**
+   * Generates link headers for each referenced entity.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   Entity that has reference fields.
+   *
+   * @return string[]
+   *   Array of link headers
+   */
+  protected function generateEntityReferenceLinks(EntityInterface $entity) {
+    // Use the node to add link headers for each entity reference.
+    $entity_type = $entity->getEntityType()->id();
+    $bundle = $entity->bundle();
+
+    // Get all fields for the entity.
+    $fields = $this->entityFieldManager->getFieldDefinitions($entity_type, $bundle);
+
+    // Strip out everything but entity references that are not base fields.
+    $entity_reference_fields = array_filter($fields, function ($field) {
+      return $field->getFieldStorageDefinition()->isBaseField() == FALSE && $field->getType() == "entity_reference";
+    });
+
+    // Collect links for referenced entities.
+    $links = [];
+    foreach ($entity_reference_fields as $field_name => $field_definition) {
+      foreach ($entity->get($field_name)->referencedEntities() as $referencedEntity) {
+        // Headers are subject to an access check.
+        if ($referencedEntity->access('view')) {
+          $entity_url = $referencedEntity->url('canonical', ['absolute' => TRUE]);
+          $field_label = $field_definition->label();
+          $links[] = "<$entity_url>; rel=\"related\"; title=\"$field_label\"";
+        }
+      }
+    }
+
+    return $links;
+  }
+
+  /**
+   * Generates link headers for REST endpoints.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   Entity that has reference fields.
+   *
+   * @return string[]
+   *   Array of link headers
+   */
+  protected function generateRestLinks(EntityInterface $entity) {
+    $rest_resource_config_storage = $this->entityTypeManager->getStorage('rest_resource_config');
+    $entity_type = $entity->getEntityType()->id();
+    $rest_resource_config = $rest_resource_config_storage->load("entity.$entity_type");
+
+    $links = [];
+    $route_name = $this->routeMatch->getRouteName();
+
+    if ($rest_resource_config) {
+      $configuration = $rest_resource_config->get('configuration');
+
+      foreach ($configuration['GET']['supported_formats'] as $format) {
+        switch ($format) {
+          case 'json':
+            $mime = 'application/json';
+            break;
+
+          case 'jsonld':
+            $mime = 'application/ld+json';
+            break;
+
+          case 'hal_json':
+            $mime = 'application/hal+json';
+            break;
+
+          case 'xml':
+            $mime = 'application/xml';
+            break;
+
+          default:
+            continue;
+        }
+
+        $meta_route_name = "rest.entity.$entity_type.GET.$format";
+
+        if ($route_name == $meta_route_name) {
+          continue;
+        }
+
+        $route_params = [$entity_type => $entity->id()];
+
+        if (!$this->accessManager->checkNamedRoute($meta_route_name, $route_params, $this->account)) {
+          continue;
+        }
+
+        $meta_url = Url::fromRoute($meta_route_name, $route_params)
+          ->setAbsolute()
+          ->toString();
+
+        $links[] = "<$meta_url?_format=$format>; rel=\"alternate\"; type=\"$mime\"";
+      }
+    }
+
+    return $links;
+  }
+
   /**
    * Adds resource-specific link headers to appropriate responses.
    *

src/EventSubscriber/MediaLinkHeaderSubscriber.php

@@ -2,11 +2,8 @@
 
 namespace Drupal\islandora\EventSubscriber;
 
-use Drupal\Core\Entity\EntityFieldManager;
-use Drupal\Core\Entity\EntityTypeManagerInterface;
-use Drupal\Core\Entity\FieldableEntityInterface;
-use Drupal\Core\Routing\RouteMatchInterface;
 use Drupal\Core\Url;
+use Drupal\media_entity\MediaInterface;
 use Symfony\Component\EventDispatcher\EventSubscriberInterface;
 use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
 
@@ -17,80 +14,77 @@ use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
  */
 class MediaLinkHeaderSubscriber extends LinkHeaderSubscriber implements EventSubscriberInterface {
 
-  /**
-   * Media storage interface.
-   *
-   * @var \Drupal\Core\Entity\EntityStorageInterface
-   */
-  protected $mediaBundleStorage;
-
-  /**
-   * MediaLinkHeaderSubscriber constructor.
-   *
-   * @param \Drupal\Core\Entity\EntityFieldManager $entity_field_manager
-   *   The entity field manager.
-   * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
-   *   The route match object.
-   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
-   *   The entity type manager.
-   */
-  public function __construct(
-    EntityFieldManager $entity_field_manager,
-    RouteMatchInterface $route_match,
-    EntityTypeManagerInterface $entity_type_manager) {
-    $this->mediaBundleStorage = $entity_type_manager->getStorage('media_bundle');
-    parent::__construct($entity_field_manager, $route_match);
-  }
-
   /**
    * {@inheritdoc}
    */
   public function onResponse(FilterResponseEvent $event) {
     $response = $event->getResponse();
 
-    $entity = $this->getObject($response, 'media');
+    $media = $this->getObject($response, 'media');
 
-    if ($entity === FALSE) {
+    if ($media === FALSE) {
       return;
     }
 
-    $media_bundle = $this->mediaBundleStorage->load($entity->bundle());
+    $links = array_merge(
+      $this->generateEntityReferenceLinks($media),
+      $this->generateRestLinks($media),
+      $this->generateMediaLinks($media)
+    );
+
+    // Add the link headers to the response.
+    if (empty($links)) {
+      return;
+    }
+
+    $response->headers->set('Link', $links, FALSE);
+  }
+
+  /**
+   * Generates link headers for the described file and source update routes.
+   *
+   * @param \Drupal\media_entity\MediaInterface $media
+   *   Media to generate link headers.
+   *
+   * @return string[]
+   *   Array of link headers
+   */
+  protected function generateMediaLinks(MediaInterface $media) {
+    $media_bundle = $this->entityTypeManager->getStorage('media_bundle')->load($media->bundle());
 
     $type_configuration = $media_bundle->getTypeConfiguration();
 
+    $links = [];
+
+    $update_route_name = 'islandora.media_source_update';
+    $update_route_params = ['media' => $media->id()];
+    if ($this->accessManager->checkNamedRoute($update_route_name, $update_route_params, $this->account)) {
+      $edit_media_url = Url::fromRoute($update_route_name, $update_route_params)
+        ->setAbsolute()
+        ->toString();
+      $links[] = "<$edit_media_url>; rel=\"edit-media\"";
+    }
+
     if (!isset($type_configuration['source_field'])) {
-      return;
+      return $links;
     }
     $source_field = $type_configuration['source_field'];
 
     if (empty($source_field) ||
-      !$entity instanceof FieldableEntityInterface ||
-      !$entity->hasField($source_field)
+        !$media->hasField($source_field)
     ) {
-      return;
+      return $links;
     }
 
     // Collect file links for the media.
-    $links = [];
-    foreach ($entity->get($source_field)->referencedEntities() as $referencedEntity) {
-      if ($entity->access('view')) {
+    foreach ($media->get($source_field)->referencedEntities() as $referencedEntity) {
+      if ($referencedEntity->access('view')) {
         $file_url = $referencedEntity->url('canonical', ['absolute' => TRUE]);
-        $edit_media_url = Url::fromRoute('islandora.media_source_update', ['media' => $referencedEntity->id()])
-          ->setAbsolute()
-          ->toString();
         $links[] = "<$file_url>; rel=\"describes\"; type=\"{$referencedEntity->getMimeType()}\"";
-        $links[] = "<$edit_media_url>; rel=\"edit-media\"";
       }
     }
 
-    // Exit early if there aren't any.
-    if (empty($links)) {
-      return;
-    }
-
-    // Add the link headers to the response.
-    $response->headers->set('Link', $links, FALSE);
-
+    return $links;
   }
 
 }

src/EventSubscriber/NodeLinkHeaderSubscriber.php

@@ -21,42 +21,22 @@ class NodeLinkHeaderSubscriber extends LinkHeaderSubscriber implements EventSubs
   public function onResponse(FilterResponseEvent $event) {
     $response = $event->getResponse();
 
-    $entity = $this->getObject($response, 'node');
+    $node = $this->getObject($response, 'node');
 
-    if ($entity === FALSE) {
+    if ($node === FALSE) {
       return;
     }
 
-    // Use the node to add link headers for each entity reference.
-    $bundle = $entity->bundle();
-
-    // Get all fields for the entity.
-    $fields = $this->entityFieldManager->getFieldDefinitions('node', $bundle);
-
-    // Strip out everything but entity references that are not base fields.
-    $entity_reference_fields = array_filter($fields, function ($field) {
-      return $field->getFieldStorageDefinition()->isBaseField() == FALSE && $field->getType() == "entity_reference";
-    });
-
-    // Collect links for referenced entities.
-    $links = [];
-    foreach ($entity_reference_fields as $field_name => $field_definition) {
-      foreach ($entity->get($field_name)->referencedEntities() as $referencedEntity) {
-        // Headers are subject to an access check.
-        if ($referencedEntity->access('view')) {
-          $entity_url = $referencedEntity->url('canonical', ['absolute' => TRUE]);
-          $field_label = $field_definition->label();
-          $links[] = "<$entity_url>; rel=\"related\"; title=\"$field_label\"";
-        }
-      }
-    }
+    $links = array_merge(
+      $this->generateEntityReferenceLinks($node),
+      $this->generateRestLinks($node)
+    );
 
-    // Exit early if there aren't any.
+    // Add the link headers to the response.
     if (empty($links)) {
       return;
     }
 
-    // Add the link headers to the response.
     $response->headers->set('Link', $links, FALSE);
   }
 

tests/src/Functional/IslandoraFunctionalTestBase.php

@@ -4,6 +4,8 @@ namespace Drupal\Tests\islandora\Functional;
 
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Url;
+use Drupal\rest\Entity\RestResourceConfig;
+use Drupal\rest\RestResourceConfigInterface;
 use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\TestFileCreationTrait;
 
@@ -38,6 +40,144 @@ class IslandoraFunctionalTestBase extends BrowserTestBase {
     $this->container->get('entity_type.manager')->getStorage('context')->load('media')->delete();
     $this->container->get('entity_type.manager')->getStorage('context')->load('file')->delete();
 
+    // Set up basic REST config.
+    // Delete the node rest config that's bootstrapped with Drupal.
+    $this->container->get('entity_type.manager')->getStorage('rest_resource_config')->load('entity.node')->delete();
+
+    // Create our own for Nodes, Media, and Files.
+    $this->container->get('entity_type.manager')->getStorage('rest_resource_config')->create([
+      'id' => 'entity.node',
+      'granularity' => RestResourceConfigInterface::METHOD_GRANULARITY,
+      'configuration' => [
+        'GET' => [
+          'supported_auth' => [
+            'cookie',
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+            'jsonld',
+          ],
+        ],
+        'POST' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+        'DELETE' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+        'PATCH' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+      ],
+    ])->save();
+    $this->container->get('entity_type.manager')->getStorage('rest_resource_config')->create([
+      'id' => 'entity.media',
+      'granularity' => RestResourceConfigInterface::METHOD_GRANULARITY,
+      'configuration' => [
+        'GET' => [
+          'supported_auth' => [
+            'cookie',
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+            'jsonld',
+          ],
+        ],
+        'POST' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+        'DELETE' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+        'PATCH' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+      ],
+    ])->save();
+    RestResourceConfig::create([
+      'id' => 'entity.file',
+      'granularity' => RestResourceConfigInterface::METHOD_GRANULARITY,
+      'configuration' => [
+        'GET' => [
+          'supported_auth' => [
+            'cookie',
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+            'jsonld',
+          ],
+        ],
+        'POST' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+        'DELETE' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+        'PATCH' => [
+          'supported_auth' => [
+            'basic_auth',
+            'jwt_auth',
+          ],
+          'supported_formats' => [
+            'json',
+          ],
+        ],
+      ],
+    ])->save();
+
     // Create a test content type.
     $test_type = $this->container->get('entity_type.manager')->getStorage('node_type')->create([
       'type' => 'test_type',

tests/src/Functional/MappingUriPredicateReactionTest.php

@@ -33,25 +33,6 @@ class MappingUriPredicateReactionTest extends IslandoraFunctionalTestBase {
       ])
       ->save();
 
-    $resourceConfigStorage = $this->container
-      ->get('entity_type.manager')
-      ->getStorage('rest_resource_config');
-    // There is already a setting for entity.node, so delete it.
-    $resourceConfigStorage
-      ->delete($resourceConfigStorage
-        ->loadMultiple(['entity.node']));
-    // Create it new.
-    $resourceConfigStorage->create([
-      'id' => 'entity.node',
-      'granularity' => 'resource',
-      'configuration' => [
-        'methods' => ['GET'],
-        'authentication' => ['basic_auth', 'cookie'],
-        'formats' => ['jsonld'],
-      ],
-      'status' => TRUE,
-    ])->save(TRUE);
-
     $this->container->get('router.builder')->rebuildIfNeeded();
   }
 

tests/src/Functional/MediaLinkHeaderTest.php

@@ -33,6 +33,21 @@ class MediaLinkHeaderTest extends IslandoraFunctionalTestBase {
       $this->validateLinkHeaderWithUrl('edit-media', $urls['file']['rest'], '', '') == 1,
       "Malformed 'edit-media' link header"
     );
+
+    // Check for links to REST endpoints for metadata.
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', $urls['media'] . "?_format=json", NULL, 'application/json') == 1,
+      "Media must have link header pointing to json REST endpoint."
+    );
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', $urls['media'] . "?_format=jsonld", NULL, 'application/ld+json') == 1,
+      "Media must have link header pointing to jsonld REST endpoint."
+    );
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', $urls['media'] . "?_format=xml", NULL, 'application/xml') == 0,
+      "Media must not have link header pointing to disabled xml REST endpoint."
+    );
+
   }
 
 }

tests/src/Functional/MediaSourceUpdateTest.php

@@ -11,27 +11,6 @@ use Drupal\Core\Url;
  */
 class MediaSourceUpdateTest extends IslandoraFunctionalTestBase {
 
-  /**
-   * {@inheritdoc}
-   */
-  public function setUp() {
-    parent::setUp();
-
-    $media_rest_resource = $this->container->get('entity_type.manager')->getStorage('rest_resource_config')->create([
-      'id' => 'entity.media',
-      'granularity' => 'resource',
-      'configuration' => [
-        'methods' => ['GET'],
-        'authentication' => ['basic_auth'],
-        'formats' => ['json'],
-      ],
-      'status' => TRUE,
-    ]);
-    $media_rest_resource->save(TRUE);
-
-    $this->container->get('router.builder')->rebuildIfNeeded();
-  }
-
   /**
    * @covers \Drupal\islandora\Controller\MediaSourceController::put
    */

tests/src/Functional/NodeLinkHeaderTest.php

@@ -10,7 +10,7 @@ use Drupal\Tests\media_entity\Functional\MediaEntityFunctionalTestTrait;
  *
  * @group islandora
  */
-class RelatedLinkHeaderTest extends IslandoraFunctionalTestBase {
+class NodeLinkHeaderTest extends IslandoraFunctionalTestBase {
 
   use EntityReferenceTestTrait;
   use MediaEntityFunctionalTestTrait;
@@ -92,23 +92,23 @@ class RelatedLinkHeaderTest extends IslandoraFunctionalTestBase {
   /**
    * @covers \Drupal\islandora\EventSubscriber\NodeLinkHeaderSubscriber::onResponse
    */
-  public function testRelatedLinkHeader() {
+  public function testNodeLinkHeaders() {
     // Create a test user that can see media.
     $account = $this->drupalCreateUser([
       'view media',
     ]);
     $this->drupalLogin($account);
 
-    // Visit the other, there should not be a header since it does not even
-    // have the field.
+    // Visit the other, there should not be a related header since it does not
+    // even have the field.
     $this->drupalGet('node/' . $this->other->id());
     $this->assertTrue(
       $this->doesNotHaveLinkHeader('related'),
       "Node that does not have entity reference field must not return related link header."
     );
 
-    // Visit the referenced node, there should not be a header since its
-    // entity reference field is empty.
+    // Visit the referenced node, there should not be a related header since
+    // its entity reference field is empty.
     $this->drupalGet('node/' . $this->referenced->id());
     $this->assertTrue(
       $this->doesNotHaveLinkHeader('related'),
@@ -127,12 +127,41 @@ class RelatedLinkHeaderTest extends IslandoraFunctionalTestBase {
       "Malformed related link header"
     );
 
+    // Check for links to REST endpoints for metadata.
+    $entity_url = $this->referencer->toUrl('canonical', ['absolute' => TRUE])
+      ->toString();
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', "$entity_url?_format=json", NULL, 'application/json') == 1,
+      "Node must have link header pointing to json REST endpoint."
+    );
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', "$entity_url?_format=jsonld", NULL, 'application/ld+json') == 1,
+      "Node must have link header pointing to jsonld REST endpoint."
+    );
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', "$entity_url?_format=xml", NULL, 'application/xml') == 0,
+      "Node must not have link header pointing to disabled xml REST endpoint."
+    );
+
+    // Check that the current representation is not advertised when visitng
+    // a REST endpoint (e.g. the json link header doesn't appear when you're
+    // visiting the ?_format=json endpoint).
+    $this->drupalGet('node/' . $this->referencer->id(), ['query' => ['_format' => 'json']]);
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', "$entity_url?_format=json", NULL, 'application/json') == 0,
+      "Node must not have link header pointing to json REST endpoint when vising the json REST endpoint."
+    );
+    $this->assertTrue(
+      $this->validateLinkHeaderWithUrl('alternate', "$entity_url?_format=jsonld", NULL, 'application/ld+json') == 1,
+      "Node must have link header pointing to jsonld REST endpoint when visiting the json REST endpoint."
+    );
+
     // Log in as anonymous.
     $account = $this->drupalCreateUser();
     $this->drupalLogin($account);
 
     // Visit the referencer. It should return a rel="related" link header
-    // for both the referenced node and media entity.
+    // for both the referenced node bun not the media entity b/c permissions.
     $this->drupalGet('node/' . $this->referencer->id());
     $this->assertTrue(
       $this->validateLinkHeaderWithEntity('related', $this->referenced, 'Referenced Entity') == 1,