code: public function setSortBy($sortKeys){
  
  		if($sortKeys==null){
  			$sortKeys=[];
  		}
  
  		if(!is_array($sortKeys)){
  			$sortKeys=[$sortKeys];
  		}
  		$this->sortKeys=$sortKeys;
  	}
docs: Set sortable column by Keys
  
  @param mixed $sortKeys sort by list of id