laravel 多条件搜索

$model = new Article_list();

    $res = $request->only(['label_id','brand_id','course_id','phone']);

    if (!empty($res)){

        if ($res['phone']){
            $model = $model->where('phone','like','%'.$res['phone'].'%');
        }
        if ($res['label_id']){

            $model = $model->where('label_id','=',$res['label_id']);

        }if ($res['brand_id']){

            $model = $model->where('brand_id','=',$res['brand_id']);

        }
        if ($res['course_id']){

            $model = $model->where('course_id','=',$res['course_id']);

        }
    }
     


    $count=$model->count();//总数目
    $Category= $this->tree();
   
    

    $data=$this->page($page,$count);
     $data['pagesize']='20';

  $users=$model->offset(($data['currentPage']-1)*$data['pagesize'])->limit($data['pagesize'])->orderBy('article_id','DESC')->get();