Issue #3414661: Serial not generating on entity save in certain contexts

Closes #3414661

serial.module

@@ -5,6 +5,8 @@
  * The Serial module main file.
  */
 
+use Drupal\Core\Entity\ContentEntityTypeInterface;
+use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
 use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\Core\Url;
@@ -89,6 +91,56 @@ function serial_clone_node_alter(Node &$node, $context) {
   }
 }
 
+/**
+ * Implements hook_entity_insert().
+ *
+ * Generate serial value for other contexts
+ * such as hook_form_alter(), feeds import etc.
+ */
+function serial_entity_insert(EntityInterface $entity) {
+  /** @var \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager */
+  $entity_type_manager = \Drupal::entityTypeManager();
+
+  /** @var \Drupal\Core\Entity\ContentEntityTypeInterface $content_entity_type */
+  $content_entity_type = $entity_type_manager
+    ->getDefinition($entity->getEntityTypeId());
+
+  // Check if definition belongs to
+  // \Drupal\Core\Entity\ContentEntityTypeInterface.
+  // Skip generation of serial if not.
+  if (!$content_entity_type instanceof ContentEntityTypeInterface) {
+    return;
+  }
+
+  // Load the field definitions.
+  $field_definitions = \Drupal::service('entity_field.manager')
+    ->getFieldDefinitions($entity->getEntityTypeId(), $entity->bundle());
+
+  // Loop through field definitions to look for serial field, and pre-populate
+  // serial value if empty.
+  foreach ($field_definitions as $field_name => $field_definition) {
+    if (!empty($field_definition->getTargetBundle())
+      && $field_definition->getType() === SerialStorageInterface::SERIAL_FIELD_TYPE
+      && $entity->$field_name->isEmpty()) {
+      /** @var \Drupal\serial\SerialStorageInterface $serial_storage */
+      $serial_value = \Drupal::service('serial.sql_storage')
+        ->generateValue($field_definition, $entity, TRUE);
+
+      // Get the starting value from the storage settings.
+      $start_value = $field_definition->getSetting('start_value');
+
+      // Subtract one as it is already added serial storage.
+      $serial = ($serial_value + $start_value) - 1;
+
+      // Set serial.
+      $entity->set($field_name, $serial);
+
+      // Save entity.
+      $entity->save();
+    }
+  }
+}
+
 /**
  * Implements hook_theme().
  */