private function setOrderBy()
    {
        if (isset($this->requestParams['order']) && count($this->requestParams['order'])) {
            $counter = count($this->requestParams['order']);

            for ($i = 0; $i < $counter; ++$i) {
                $columnIdx = (integer) $this->requestParams['order'][$i]['column'];
                $requestColumn = $this->requestParams['columns'][$columnIdx];

                if ('true' == $requestColumn['orderable']) {
                    $this->qb->addOrderBy(
                        $this->orderColumns[$columnIdx],
                        $this->requestParams['order'][$i]['dir']
                    );
                }
            }
        }

        return $this;
    }