private function getNotification($id)
    {
        /** @var Notification $notification */
        $class = $this->notificationClass;
        $notification = $class::findOne($id);
        if (!$notification) {
            throw new HttpException(404, "Unknown notification");
        }

        if ($notification->user_id != $this->user_id) {
            throw new HttpException(500, "Not your notification");
        }

        return $notification;
    }