Meta link headers (Islandora#81)

* Adding rel=alternate link headers for metadata REST endpoints * Missed a few spots in tests still bootstrapping their own REST config.
nigelgbanks · Mar 20, 2018 · 6e4815e · 6e4815e
1 parent e62f754
commit 6e4815e
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Showing 9 changed files with 389 additions and 128 deletions.
diff --git a/islandora.services.yml b/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:

diff --git a/src/EventSubscriber/LinkHeaderSubscriber.php b/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 @@
  */
 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 @@ protected function getObject(Response $response, $object_type) {
     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.
    *

diff --git a/src/EventSubscriber/MediaLinkHeaderSubscriber.php b/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 @@
  */
 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;
   }
 
 }
diff --git a/src/EventSubscriber/NodeLinkHeaderSubscriber.php b/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);
   }