public function setSearchType($search_type)
    {
        switch ($search_type) {
            case self::RECORD_RECORD:
            default:
                $this->search_type = self::RECORD_RECORD;
                break;
            case self::RECORD_GROUPING:
            case self::RECORD_STORY:
                $this->search_type = self::RECORD_GROUPING;
                break;
        }

        return $this;
    }