From cb27f971633297921a904ab53a63ea6c8c492736 Mon Sep 17 00:00:00 2001
From: damienmckenna <damienmckenna@108450.no-reply.drupal.org>
Date: Mon, 5 Dec 2016 15:30:02 +0100
Subject: [PATCH] Issue #2674882 by DamienMcKenna, miro_dietiker,
 greggmarshall, Grimreaper: Add Multiversion compatibility to Entity Reference
 Revisions (for Paragraphs, etc)

---
 entity_reference_revisions.module                | 11 ++++
 src/EntityReferenceRevisionsMultiversionItem.php | 68 ++++++++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 src/EntityReferenceRevisionsMultiversionItem.php

diff --git a/entity_reference_revisions.module b/entity_reference_revisions.module
index ba9ac49..b7b258f 100644
--- a/entity_reference_revisions.module
+++ b/entity_reference_revisions.module
@@ -218,3 +218,14 @@ function entity_reference_revisions_form_field_ui_field_storage_add_form_alter(a
   unset($form['add']['new_storage_type']['#options'][(string) t('Reference revisions')]['entity_reference_revisions']);
   $form['add']['new_storage_type']['#options'][(string) t('Reference revisions')]['entity_reference_revisions'] = t('Other…');
 }
+
+/**
+ * Implements hook_field_info_alter().
+ */
+function entity_reference_revisions_field_info_alter(&$info) {
+  if (\Drupal::moduleHandler()->moduleExists('multiversion')) {
+    if (isset($info['entity_reference_revisions'])) {
+      $info['entity_reference_revisions']['class'] = '\Drupal\entity_reference_revisions\EntityReferenceRevisionsMultiversionItem';
+    }
+  }
+}
diff --git a/src/EntityReferenceRevisionsMultiversionItem.php b/src/EntityReferenceRevisionsMultiversionItem.php
new file mode 100644
index 0000000..32f8124
--- /dev/null
+++ b/src/EntityReferenceRevisionsMultiversionItem.php
@@ -0,0 +1,68 @@
+<?php
+
+namespace Drupal\entity_reference_revisions;
+
+use Drupal\entity_reference_revisions\Plugin\Field\FieldType\EntityReferenceRevisionsItem;
+
+/**
+ * Add compatibility with the multiversion module.
+ *
+ * Allow to handle the behavior of the multiversion module with entity reference
+ * revisions field.
+ */
+class EntityReferenceRevisionsMultiversionItem extends EntityReferenceRevisionsItem {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function preSave() {
+    if ($this->hasNewEntity()) {
+      // As part of a bulk or replication operation there might be multiple
+      // parent entities wanting to auto-create the same reference. So at this
+      // point this entity might already be saved, so look it up by UUID and map
+      // it correctly.
+      // @see \Drupal\relaxed\BulkDocs\BulkDocs::save()
+      if ($this->entity->isNew()) {
+        $uuid = $this->entity->uuid();
+        $uuid_index = \Drupal::service('multiversion.entity_index.factory')
+          ->get('multiversion.entity_index.uuid');
+        if ($uuid && $record = $uuid_index->get($uuid)) {
+          /** @var \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager */
+          $entity_type_manager = \Drupal::service('entity_type.manager');
+          $entity_type_id = $this->entity->getEntityTypeId();
+
+          // Now decide what revision to use.
+          $id_key = $entity_type_manager
+            ->getDefinition($entity_type_id)
+            ->getKey('id');
+          $revision_key = $entity_type_manager
+            ->getDefinition($entity_type_id)
+            ->getKey('revision');
+
+          // If the referenced entity is a stub, but an entity already was
+          // created, then load and use that entity instead without saving.
+          if ($this->entity->_rev->is_stub && is_numeric($record['entity_id'])) {
+            $this->entity = $entity_type_manager
+              ->getStorage($entity_type_id)
+              ->loadRevision($record['revision_id']);
+          }
+          // If the referenced entity is not a stub then map it with the correct
+          // ID from the existing record and save it.
+          elseif (!$this->entity->_rev->is_stub) {
+            $this->entity->{$id_key}->value = $record['entity_id'];
+            $this->entity->{$revision_key}->value = $record['revision_id'];
+            $this->entity->enforceIsNew(FALSE);
+            $this->entity->save();
+          }
+        }
+        // Just save the entity if no previous record exists.
+        else {
+          $this->entity->save();
+        }
+      }
+    }
+
+    parent::preSave();
+  }
+
+}
-- 
1.9.1