private function _checkRepositoryProperty()
    {
        if (!$this->repository) {
            if (Lang::has('resource-controller.propertynotset')) {
                $message = trans('resource-controller.propertynotset', ['property' => '$repository']);
            } else {
                $message = '$repository property must be set.';
            }

            throw new ResourceControllerException($message);
        }
    }