Embed Paragraph Content in Normalized Parent Entities (REST) issue fix- 2848878.

src/Normalizer/EntityReferenceRevisionItemNormalizer.php

@@ -2,6 +2,8 @@
 
 namespace Drupal\entity_reference_revisions\Normalizer;
 
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\entity_reference_revisions\EntityNeedsSaveInterface;
 use Drupal\entity_reference_revisions\Plugin\Field\FieldType\EntityReferenceRevisionsItem;
 use Drupal\hal\Normalizer\EntityReferenceItemNormalizer;
 
@@ -17,10 +19,45 @@ class EntityReferenceRevisionItemNormalizer extends EntityReferenceItemNormalize
    */
   protected $supportedInterfaceOrClass = EntityReferenceRevisionsItem::class;
 
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * Set the entity type manager.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   */
+  public function setEntityTypeManager(EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
   /**
    * {@inheritdoc}
    */
   protected function constructValue($data, $context) {
+    $field_item = $context['target_instance'];
+    /** @var \Drupal\entity_reference_revisions\Plugin\Field\FieldType\EntityReferenceRevisionsItem $field_item */
+    $field_definition = $field_item->getFieldDefinition();
+    $target_type_id = $field_definition->getSetting('target_type');
+    $target_type = $this->entityTypeManager->getDefinition($target_type_id);
+
+    // If the target type has a revision parent type field and that field is
+    // part of data, this is a composite normalization.
+    $parent_type_field = $target_type->get('entity_revision_parent_type_field');
+    if ($parent_type_field && isset($data[$parent_type_field])) {
+
+      // Denormalize the embedded entity, if it implements the
+      // EntityNeedsSaveInterface interface, ensure that it will be saved.
+      if ($target_entity = $this->serializer->denormalize($data, $target_type->getClass(), 'hal_json')) {
+        return ['entity' => $target_entity];
+      }
+    }
+
     $value = parent::constructValue($data, $context);
     if ($value) {
       $value['target_revision_id'] = $data['target_revision_id'];
@@ -33,10 +70,35 @@ class EntityReferenceRevisionItemNormalizer extends EntityReferenceItemNormalize
    */
   public function normalize($field_item, $format = NULL, array $context = array()) {
     $data = parent::normalize($field_item, $format, $context);
-    $field_name = $field_item->getParent()->getName();
+    /** @var \Drupal\entity_reference_revisions\Plugin\Field\FieldType\EntityReferenceRevisionsItem $field_item */
+    $target_entity = $field_item->get('entity')->getValue();
     $entity = $field_item->getEntity();
+    $field_name = $field_item->getParent()->getName();
     $field_uri = $this->linkManager->getRelationUri($entity->getEntityTypeId(), $entity->bundle(), $field_name, $context);
-    $data['_embedded'][$field_uri][0]['target_revision_id'] = $field_item->target_revision_id;
+
+    if ($target_entity->getEntityType()->get('entity_revision_parent_id_field')) {
+      $embedded_context = $context;
+      $embedded_context['included_fields'] = NULL;
+      $embedded = $this->serializer->normalize($target_entity, $format, $embedded_context);
+
+      // Restore lang key if it was set by our parent.
+      if (isset($data['_links'][$field_uri][0]['lang'])) {
+        $embedded['lang'] = $data['_links'][$field_uri][0]['lang'];
+      }
+
+      // Remove empty links.
+      if (empty($data['_links'][$field_uri][0]['href'])) {
+        unset($data['_links'][$field_uri]);
+      }
+      if (empty($embedded['_links']['self']['href'])) {
+        unset($embedded['_links']['self']);
+      }
+
+      $data['_embedded'][$field_uri][0] = $embedded;
+    }
+    else {
+      $data['_embedded'][$field_uri][0]['target_revision_id'] = $field_item->target_revision_id;
+    }
     return $data;
   }