Issue #2233157 by blueminds, Jalandhar: Make the comment entity_id be a reference field.

core/modules/comment/lib/Drupal/comment/Entity/Comment.php

@@ -216,7 +216,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setDescription(t('The parent comment ID if this is a reply to a comment.'))
       ->setSetting('target_type', 'comment');
 
-    $fields['entity_id'] = FieldDefinition::create('integer')
+    $fields['entity_id'] = FieldDefinition::create('entity_reference')
       ->setLabel(t('Entity ID'))
       ->setDescription(t('The ID of the entity of which this comment is a reply.'))
       ->setRequired(TRUE);
@@ -302,6 +302,16 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     return $fields;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function bundleFieldDefinitions(EntityTypeInterface $entity_type, $bundle, array $base_field_definitions) {
+    list($target_type) = explode('__', $bundle, 2);
+    $fields['entity_id'] = clone $base_field_definitions['entity_id'];
+    $fields['entity_id']->setSetting('target_type', $target_type);
+    return $fields;
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -321,16 +331,14 @@ public function getParentComment() {
    * {@inheritdoc}
    */
   public function getCommentedEntity() {
-    $entity_id = $this->getCommentedEntityId();
-    $entity_type = $this->getCommentedEntityTypeId();
-    return entity_load($entity_type, $entity_id);
+    return $this->get('entity_id')->entity;
   }
 
   /**
    * {@inheritdoc}
    */
   public function getCommentedEntityId() {
-    return $this->get('entity_id')->value;
+    return $this->get('entity_id')->target_id;
   }
 
   /**

core/modules/comment/lib/Drupal/comment/Tests/CommentValidationTest.php

@@ -39,6 +39,7 @@ public static function getInfo() {
   public function setUp() {
     parent::setUp();
     $this->installSchema('node', array('node', 'node_field_data', 'node_field_revision', 'node_revision'));
+    $this->installSchema('comment', array('comment_entity_statistics'));
   }
 
   /**

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

@@ -17,7 +17,7 @@ class EntityTest extends NormalizerTestBase {
    *
    * @var array
    */
-  public static $modules = array('node', 'taxonomy');
+  public static $modules = array('node', 'taxonomy', 'comment');
 
   /**
    * {@inheritdoc}
@@ -39,6 +39,7 @@ function setUp() {
     \Drupal::service('router.builder')->rebuild();
     $this->installSchema('system', array('sequences'));
     $this->installSchema('node', array('node', 'node_field_data', 'node_revision', 'node_field_revision'));
+    $this->installSchema('comment', array('comment', 'comment_entity_statistics'));
     $this->installSchema('user', array('users_roles'));
     $this->installSchema('taxonomy', array('taxonomy_term_data', 'taxonomy_term_hierarchy'));
   }
@@ -118,4 +119,59 @@ public function testTerm() {
     }
   }
 
+  /**
+   * Tests the normalization of comments.
+   */
+  public function testComment() {
+    $node_type = entity_create('node_type', array('type' => 'example_type'));
+    $node_type->save();
+
+    $user = entity_create('user', array('name' => $this->randomName()));
+    $user->save();
+
+    $node = entity_create('node', array(
+      'title' => $this->randomName(),
+      'uid' => $user->id(),
+      'type' => $node_type->id(),
+      'status' => NODE_PUBLISHED,
+      'promote' => 1,
+      'sticky' => 0,
+      'body' => array(
+        'value' => $this->randomName(),
+        'format' => $this->randomName(),
+      )
+    ));
+    $node->save();
+
+    $this->container->get('comment.manager')->addDefaultField('node', 'example_type');
+
+    $comment = entity_create('comment', array(
+      'uid' => $user->id(),
+      'subject' => $this->randomName(),
+      'comment_body' => $this->randomName(),
+      'entity_id' => $node->id(),
+      'entity_type' => 'node',
+      'field_name' => 'comment'
+    ));
+    $comment->save();
+
+    $original_values = $comment->toArray();
+    unset($original_values['cid']);
+
+    $normalized = $this->serializer->normalize($comment, $this->format);
+    $denormalized_comment = $this->serializer->denormalize($normalized, 'Drupal\comment\Entity\Comment', $this->format);
+
+    // Verify that the ID and revision ID were skipped by the normalizer.
+    $this->assertEqual(NULL, $denormalized_comment->id());
+
+    // Loop over the remaining fields and verify that they are identical.
+    foreach ($original_values as $field_name => $field_values) {
+      // The target field comes with revision id which is not set.
+      if (array_key_exists('revision_id', $field_values[0])) {
+        unset($field_values[0]['revision_id']);
+      }
+      $this->assertEqual($field_values, $denormalized_comment->get($field_name)->getValue());
+    }
+  }
+
 }