public function getSortField()
    {
        if ($this->_sortField === false) {
            return [];
        }

        if ($this->_sortField) {
            // 
            if (is_array($this->_sortField)) {
                return [$this->name => $this->_sortField];
            } 

            return [$this->name => [
                'asc' => [$this->_sortField => SORT_ASC],
                'desc' => [$this->_sortField => SORT_DESC]
            ]];
        }
        
        return [$this->name];
    }