public function serialize(AbstractQueryRequest $request) {
        $parameters = parent::serialize($request);

        // serializing column names
        if (isset($request->columns)) {
            ArrayHelper::merge(
                $parameters,
                $this->serializeValue(
                    DataQueryControllerUIParameterNames::COLUMNS,
                    DataQueryControllerUIRequestPreparer::prepareColumns($request->columns)));
        }

        return $parameters;
    }
 public function serialize(AbstractQueryRequest $request) {
     return parent::serialize($request);
 }