Issue #1880424 by linclark, effulgentsia: Handle entity references on import.

core/modules/hal/hal.services.yml

@@ -5,6 +5,7 @@ services:
       - { name: normalizer, priority: 10 }
     calls:
       - [setLinkManager, ['@rest.link_manager']]
+      - [setEntityResolver, ['@serializer.entity_resolver']]
   serializer.normalizer.field_item.hal:
     class: Drupal\hal\Normalizer\FieldItemNormalizer
     tags:

core/modules/hal/lib/Drupal/hal/Normalizer/EntityNormalizer.php

@@ -80,7 +80,6 @@ public function denormalize($data, $class, $format = NULL, array $context = arra
     $typed_data_ids = $this->getTypedDataIds($data['_links']['type']);
     $entity = entity_create($typed_data_ids['entity_type'], array('langcode' => $langcode, 'type' => $typed_data_ids['bundle']));
 
-    // @todo Handle data in _links and _embedded, http://drupal.org/node/1880424
     // Get links and remove from data array.
     $links = $data['_links'];
     unset($data['_links']);
@@ -91,6 +90,15 @@ public function denormalize($data, $class, $format = NULL, array $context = arra
       unset($data['_embedded']);
     }
 
+    // Flatten the embedded values.
+    foreach ($embedded as $relation => $field) {
+      $field_ids = $this->linkManager->getRelationInternalIds($relation);
+      if (!empty($field_ids)) {
+        $field_name = $field_ids['field_name'];
+        $data[$field_name] = $field;
+      }
+    }
+
     // Iterate through remaining items in data array. These should all
     // correspond to fields.
     foreach ($data as $field_name => $field_data) {
@@ -166,5 +174,4 @@ protected function getTypedDataIds($types) {
 
     return $typed_data_ids;
   }
-
 }

core/modules/hal/lib/Drupal/hal/Normalizer/EntityReferenceItemNormalizer.php

@@ -7,10 +7,12 @@
 
 namespace Drupal\hal\Normalizer;
 
+use Drupal\serialization\EntityResolver\UuidReferenceInterface;
+
 /**
  * Converts the Drupal entity reference item object to HAL array structure.
  */
-class EntityReferenceItemNormalizer extends FieldItemNormalizer {
+class EntityReferenceItemNormalizer extends FieldItemNormalizer implements UuidReferenceInterface {
 
   /**
    * The interface or class that this Normalizer supports.
@@ -58,10 +60,29 @@ public function normalize($field_item, $format = NULL, array $context = array())
   }
 
   /**
-   * Implements \Symfony\Component\Serializer\Normalizer\DenormalizerInterface::denormalize()
+   * Overrides \Drupal\hal\Normalizer\FieldItemNormalizer::constructValue().
    */
-  public function denormalize($data, $class, $format = NULL, array $context = array()) {
-    // @todo Implement this in http://drupal.org/node/1880424
+  protected function constructValue($data, $context) {
+    $field_item = $context['target_instance'];
+    $field_definition = $field_item->getDefinition();
+    $target_type = $field_definition['settings']['target_type'];
+    if ($id = $this->entityResolver->resolve($this, $data, $target_type)) {
+      return array('target_id' => $id);
+    }
+    return NULL;
+  }
+
+  /**
+   * Implements \Drupal\serialization\EntityResolver\UuidReferenceInterface::getUuid().
+   */
+  public function getUuid($data) {
+    if (isset($data['uuid'])) {
+      $uuid = $data['uuid'];
+      if (is_array($uuid)) {
+        $uuid = reset($uuid);
+      }
+      return $uuid;
+    }
   }
 
 }

core/modules/hal/lib/Drupal/hal/Normalizer/FieldItemNormalizer.php

@@ -63,10 +63,25 @@ public function denormalize($data, $class, $format = NULL, array $context = arra
       }
     }
 
-    $field_item->setValue($data);
+    $field_item->setValue($this->constructValue($data, $context));
     return $field_item;
   }
 
+  /**
+   * Build the field item value using the incoming data.
+   *
+   * @param $data
+   *   The incoming data for this field item.
+   * @param $context
+   *   The context passed into the Normalizer.
+   *
+   * @return mixed
+   *   The value to use in Entity::setValue().
+   */
+  protected function constructValue($data, $context) {
+    return $data;
+  }
+
   /**
    * Get a translated version of the field item instance.
    *

core/modules/hal/lib/Drupal/hal/Normalizer/NormalizerBase.php

@@ -7,6 +7,7 @@
 
 namespace Drupal\hal\Normalizer;
 
+use Drupal\serialization\EntityResolver\EntityResolverInterface;
 use Drupal\serialization\Normalizer\NormalizerBase as SerializationNormalizerBase;
 use Symfony\Component\Serializer\Normalizer\DenormalizerInterface;
 
@@ -22,6 +23,13 @@ abstract class NormalizerBase extends SerializationNormalizerBase implements Den
    */
   protected $formats = array('hal_json');
 
+  /**
+   * The entity resolver.
+   *
+   * @var \Drupal\serialization\EntityResolver\EntityResolverInterface
+   */
+  protected $entityResolver;
+
   /**
    * The hypermedia link manager.
    *
@@ -64,4 +72,15 @@ public function setLinkManager($link_manager) {
     $this->linkManager = $link_manager;
   }
 
+  /**
+   * Sets the entity resolver.
+   *
+   * The entity resolver is used to
+   *
+   * @param \Drupal\serialization\EntityResolver\EntityResolverInterface $entity_resolver
+   */
+  public function setEntityResolver(EntityResolverInterface $entity_resolver) {
+    $this->entityResolver = $entity_resolver;
+  }
+
 }

core/modules/hal/lib/Drupal/hal/Tests/NormalizerTestBase.php

@@ -128,7 +128,7 @@ function setUp() {
       new FieldItemNormalizer(),
       new FieldNormalizer(),
     );
-    $link_manager = new LinkManager(new TypeLinkManager(new MemoryBackend('cache')), new RelationLinkManager());
+    $link_manager = new LinkManager(new TypeLinkManager(new MemoryBackend('cache')), new RelationLinkManager(new MemoryBackend('cache')));
     foreach ($normalizers as $normalizer) {
       $normalizer->setLinkManager($link_manager);
     }

core/modules/rest/lib/Drupal/rest/LinkManager/LinkManager.php

@@ -55,4 +55,11 @@ public function getTypeInternalIds($type_uri) {
   public function getRelationUri($entity_type, $bundle, $field_name) {
     return $this->relationLinkManager->getRelationUri($entity_type, $bundle, $field_name);
   }
+
+  /**
+   * Implements \Drupal\rest\LinkManager\RelationLinkManagerInterface::getRelationInternalIds().
+   */
+  public function getRelationInternalIds($relation_uri) {
+    return $this->relationLinkManager->getRelationInternalIds($relation_uri);
+  }
 }

core/modules/rest/lib/Drupal/rest/LinkManager/RelationLinkManager.php

@@ -7,24 +7,87 @@
 
 namespace Drupal\rest\LinkManager;
 
+use Drupal\Core\Cache\CacheBackendInterface;
+
 class RelationLinkManager implements RelationLinkManagerInterface{
 
   /**
-   * Get a relation link for the field.
-   *
-   * @param string $entity_type
-   *   The bundle's entity type.
-   * @param string $bundle
-   *   The name of the bundle.
-   * @param string $field_name
-   *   The name of the field.
+   * @var \Drupal\Core\Cache\CacheBackendInterface;
+   */
+  protected $cache;
+
+  /**
+   * Constructor.
    *
-   * @return array
-   *   The URI that identifies this field.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache
+   *   The cache of relation URIs and their associated Typed Data IDs.
+   */
+  public function __construct(CacheBackendInterface $cache) {
+    $this->cache = $cache;
+  }
+
+  /**
+   * Implements \Drupal\rest\LinkManager\RelationLinkManagerInterface::getRelationUri().
    */
   public function getRelationUri($entity_type, $bundle, $field_name) {
     // @todo Make the base path configurable.
     return url("rest/relation/$entity_type/$bundle/$field_name", array('absolute' => TRUE));
   }
 
+  /**
+   * Implements \Drupal\rest\LinkManager\RelationLinkManagerInterface::getRelationInternalIds().
+   */
+  public function getRelationInternalIds($relation_uri) {
+    $relations = $this->getRelations();
+    if (isset($relations[$relation_uri])) {
+      return $relations[$relation_uri];
+    }
+    return FALSE;
+  }
+
+  /**
+   * Get the array of relation links.
+   *
+   * Any field can be handled as a relation simply by changing how it is
+   * normalized. Therefore, there is no prior knowledge that can be used here
+   * to determine which fields to assign relation URIs. Instead, each field,
+   * even primitives, are given a relation URI. It is up to the caller to
+   * determine which URIs to use.
+   *
+   * @return array
+   *   An array of typed data ids (entity_type, bundle, and field name) keyed
+   *   by corresponding relation URI.
+   */
+  public function getRelations() {
+    $cid = 'rest:links:relations';
+    $cache = $this->cache->get($cid);
+    if (!$cache) {
+      $this->writeCache();
+      $cache = $this->cache->get($cid);
+    }
+    return $cache->data;
+  }
+
+  /**
+   * Writes the cache of relation links.
+   */
+  protected function writeCache() {
+    $data = array();
+
+    foreach (field_info_fields() as $field_info) {
+      foreach ($field_info['bundles'] as $entity_type => $bundles) {
+        foreach ($bundles as $bundle) {
+          $relation_uri = $this->getRelationUri($entity_type, $bundle, $field_info['field_name']);
+          $data[$relation_uri] = array(
+            'entity_type' => $entity_type,
+            'bundle' => $bundle,
+            'field_name' => $field_info['field_name'],
+          );
+        }
+      }
+    }
+    // These URIs only change when field info changes, so cache it permanently
+    // and only clear it when field_info is cleared.
+    $this->cache->set('rest:links:relations', $data, CacheBackendInterface::CACHE_PERMANENT, array('field_info' => TRUE));
+  }
 }

core/modules/rest/rest.services.yml

@@ -19,3 +19,4 @@ services:
     arguments: ['@cache.cache']
   rest.link_manager.relation:
     class: Drupal\rest\LinkManager\RelationLinkManager
+    arguments: ['@cache.cache']

core/modules/serialization/lib/Drupal/serialization/EntityResolver/ChainEntityResolver.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\serialization\EntityResolver\ChainEntityResolver
+ */
+
+namespace Drupal\serialization\EntityResolver;
+
+use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
+
+/**
+ * Resolver delegating the entity resolution to a chain of resolvers.
+ */
+class ChainEntityResolver implements EntityResolverInterface {
+
+  /**
+   * The concrete resolvers.
+   *
+   * @var array
+   */
+  protected $resolvers;
+
+  /**
+   * Constructor.
+   *
+   * @param array $resolvers
+   *   The array of concrete resolvers.
+   */
+  public function __construct(array $resolvers = array()) {
+    $this->resolvers = $resolvers;
+  }
+
+  /**
+   * Implements \Drupal\serialization\EntityResolver\EntityResolverInterface::resolve().
+   */
+  public function resolve(NormalizerInterface $normalizer, $data, $entity_type) {
+    foreach ($this->resolvers as $resolver) {
+      if ($resolved = $resolver->resolve($normalizer, $data, $entity_type)) {
+        return $resolved;
+      }
+    }
+    return NULL;
+  }
+
+}

core/modules/serialization/lib/Drupal/serialization/EntityResolver/EntityResolverInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\serialization\EntityResolver\EntityResolverInterface
+ */
+
+namespace Drupal\serialization\EntityResolver;
+
+use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
+
+interface EntityResolverInterface {
+
+  /**
+   * Returns the local ID of an entity referenced by serialized data.
+   *
+   * Drupal entities are loaded by and internally referenced by a local ID.
+   * Because different websites can use the same local ID to refer to different
+   * entities (e.g., node "1" can be a different node on foo.com and bar.com, or
+   * on example.com and staging.example.com), it is generally unsuitable for use
+   * in hypermedia data exchanges. Instead, UUIDs, URIs, or other globally
+   * unique IDs are preferred.
+   *
+   * This function takes a $data array representing partially deserialized data
+   * for an entity reference, and resolves it to a local entity ID. For example,
+   * depending on the data specification being used, $data might contain a
+   * 'uuid' key, a 'uri' key, a 'href' key, or some other data identifying the
+   * entity, and it is up to the implementor of this interface to resolve that
+   * appropriately for the specification being used.
+   *
+   * @param \Symfony\Component\Serializer\Normalizer\NormalizerInterface $normalizer
+   *   The Normalizer which is handling the data.
+   * @param array $data
+   *   The data passed into the calling Normalizer.
+   * @param string $entity_type
+   *   The type of entity being resolved; e.g., 'node' or 'user'.
+   *
+   * @return string|NULL
+   *   Returns the local entity ID, if found. Otherwise, returns NULL.
+   */
+  public function resolve(NormalizerInterface $normalizer, $data, $entity_type);
+
+}

core/modules/serialization/lib/Drupal/serialization/EntityResolver/UuidReferenceInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\serialization\EntityResolver\UuidReferenceInterface
+ */
+
+namespace Drupal\serialization\EntityResolver;
+
+/**
+ * Interface for extracting UUID from entity reference data when denormalizing.
+ */
+interface UuidReferenceInterface {
+
+  /**
+   * Get the uuid from the data array.
+   *
+   * @param array $data
+   *   The data, as was passed into the Normalizer.
+   *
+   * @return string
+   *   A UUID.
+   */
+  public function getUuid($data);
+
+}

core/modules/serialization/lib/Drupal/serialization/EntityResolver/UuidResolver.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\serialization\EntityResolver\UuidResolver
+ */
+
+namespace Drupal\serialization\EntityResolver;
+
+use Symfony\Component\Serializer\Normalizer\NormalizerInterface;
+
+/**
+ * Resolves entities from data that contains an entity UUID.
+ */
+class UuidResolver implements EntityResolverInterface {
+
+  /**
+   * Implements \Drupal\serialization\EntityResolver\EntityResolverInterface::resolve().
+   */
+  public function resolve(NormalizerInterface $normalizer, $data, $entity_type) {
+    // The normalizer is what knows the specification of the data being
+    // deserialized. If it can return a UUID from that data, and if there's an
+    // entity with that UUID, then return its ID.
+    if (($normalizer instanceof UuidReferenceInterface) && $uuid = $normalizer->getUuid($data)) {
+      if ($entity = entity_load_by_uuid($entity_type, $uuid)) {
+        return $entity->id();
+      }
+    }
+    return NULL;
+  }
+
+}

core/modules/serialization/lib/Drupal/serialization/RegisterEntityResolversCompilerPass.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\serialization\RegisterEntityResolversCompilerPass.
+ */
+
+namespace Drupal\serialization;
+
+use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
+
+/**
+ * Adds services tagged 'normalizer' and 'encoder' to the Serializer.
+ */
+class RegisterEntityResolversCompilerPass implements CompilerPassInterface {
+
+  /**
+   * Adds services to the Serializer.
+   *
+   * @param \Symfony\Component\DependencyInjection\ContainerBuilder $container
+   *   The container to process.
+   */
+  public function process(ContainerBuilder $container) {
+    $definition = $container->getDefinition('serializer.entity_resolver');
+
+    // Retrieve registered Normalizers and Encoders from the container.
+    foreach ($container->findTaggedServiceIds('entity_resolver') as $id => $attributes) {
+      $priority = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
+      $resolvers[$priority][] = new Reference($id);
+    }
+
+    // Add the registered concrete EntityResolvers to the ChainEntityResolver.
+    if (!empty($resolvers)) {
+      $definition->replaceArgument(0, $this->sort($resolvers));
+    }
+  }
+
+  /**
+   * Sorts by priority.
+   *
+   * Order services from highest priority number to lowest (reverse sorting).
+   *
+   * @param array $services
+   *   A nested array keyed on priority number. For each priority number, the
+   *   value is an array of Symfony\Component\DependencyInjection\Reference
+   *   objects, each a reference to a normalizer or encoder service.
+   *
+   * @return array
+   *   A flattened array of Reference objects from $services, ordered from high
+   *   to low priority.
+   */
+  protected function sort($services) {
+    $sorted = array();
+    krsort($services);
+
+    // Flatten the array.
+    foreach ($services as $a) {
+      $sorted = array_merge($sorted, $a);
+    }
+
+    return $sorted;
+  }
+}

core/modules/serialization/lib/Drupal/serialization/SerializationBundle.php

@@ -21,5 +21,7 @@ class SerializationBundle extends Bundle {
   public function build(ContainerBuilder $container) {
     // Add a compiler pass for adding Normalizers and Encoders to Serializer.
     $container->addCompilerPass(new RegisterSerializationClassesCompilerPass());
+    // Add a compiler pass for adding concrete Resolvers to chain Resolver.
+    $container->addCompilerPass(new RegisterEntityResolversCompilerPass());
   }
 }

core/modules/serialization/lib/Drupal/serialization/Tests/EntityResolverTest.php

+<?php
+/**
+ * @file
+ * Contains \Drupal\serialization\Tests\EntityResolverTest.
+ */
+
+namespace Drupal\serialization\Tests;
+
+class EntityResolverTest extends NormalizerTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('entity_reference', 'hal', 'rest');
+
+  /**
+   * The format being tested.
+   *
+   * @var string
+   */
+  protected $format = 'hal_json';
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Entity resolver tests',
+      'description' => 'Tests that entities references can be resolved.',
+      'group' => 'Serialization',
+    );
+  }
+
+  protected function setUp() {
+    parent::setUp();
+
+    // Create the test field.
+    $field = array(
+      'settings' => array(
+        'target_type' => 'entity_test_mulrev',
+      ),
+      'field_name' => 'field_test_entity_reference',
+      'type' => 'entity_reference',
+    );
+    field_create_field($field);
+
+    // Create the test field instance.
+    $instance = array(
+      'entity_type' => 'entity_test_mulrev',
+      'field_name' => 'field_test_entity_reference',
+      'bundle' => 'entity_test_mulrev',
+    );
+    field_create_instance($instance);
+  }
+
+  /**
+   * Test that fields referencing UUIDs can be denormalized.
+   */
+  function testUuidEntityResolver() {
+    // Create an entity to get the UUID from.
+    $entity = entity_create('entity_test_mulrev', array('type' => 'entity_test_mulrev'));
+    $entity->set('name', 'foobar');
+    $entity->set('field_test_entity_reference', array(array('target_id' => 1)));
+    $entity->save();
+
+    $field_uri = url('rest/relation/entity_test_mulrev/entity_test_mulrev/field_test_entity_reference', array('absolute' => TRUE));
+
+    $data = array(
+      '_links' => array(
+        'type' => array(
+          'href' => url('rest/type/entity_test_mulrev/entity_test_mulrev', array('absolute' => TRUE)),
+        ),
+        $field_uri => array(
+          array(
+            'href' => url('entity/entity_test_mulrev/' . $entity->id()),
+          ),
+        ),
+      ),
+      '_embedded' => array(
+        $field_uri => array(
+          array(
+            '_links' => array(
+              'self' => url('entity/entity_test_mulrev/' . $entity->id()),
+            ),