class EntityFetchByField

class EntityFetchByField extends RulesActionBase implements ContainerFactoryPluginInterface {
  
  /**
   * The entity type manager.
   *
   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
   */
  protected $entityTypeManager;
  
  /**
   * Constructs a EntityFetchByField object.
   *
   * @param array $configuration
   *   A configuration array containing information about the plugin instance.
   * @param string $plugin_id
   *   The plugin ID for the plugin instance.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity type manager service.
   */
  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager) {
    parent::__construct($configuration, $plugin_id, $plugin_definition);
    $this->entityTypeManager = $entity_type_manager;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static($configuration, $plugin_id, $plugin_definition, $container->get('entity_type.manager'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function refineContextDefinitions(array $selected_data) {
    if ($type = $this->getContextValue('type')) {
      $this->pluginDefinition['provides']['entity_fetched']
        ->setDataType("entity:{$type}");
    }
  }
  
  /**
   * Executes the action with the given context.
   *
   * @param string $type
   *   The entity type id.
   * @param string $field_name
   *   Name of the field by which the entity is to be selected.
   * @param mixed $field_value
   *   The field value of the entity to be fetched.
   * @param int $limit
   *   Limit on the maximum number of fetched entities.
   */
  protected function doExecute($type, $field_name, $field_value, $limit = NULL) {
    $storage = $this->entityTypeManager
      ->getStorage($type);
    // When retrieving entities, if $limit is not set there is no need to use
    // the query object directly.
    if (is_null($limit)) {
      $entities = $storage->loadByProperties([
        $field_name => $field_value,
      ]);
    }
    else {
      $query = $storage->getQuery();
      $entity_ids = $query->accessCheck(TRUE)
        ->condition($field_name, $field_value, '=')
        ->range(0, $limit)
        ->execute();
      $entities = $storage->loadMultiple($entity_ids);
    }
    // Set provided value.
    // @todo Ensure that the provided context has the correct entity type.
    $this->setProvidedValue('entity_fetched', $entities);
  }

}