laravel框架之无限极分类

<?php
namespace App\models\wxj;
use Illuminate\Support\Facades\DB;
use Session;

class Wxjlx
{
    public function r(){
      $sql=DB::table('wxjlx')->get();
      $result=self::fl($sql,$pid=0);
            return $result;
    }

    public function fl($data,$pid,$le=0){
        static $array=array();
        foreach ($data as $v){
            if($v->pid==$pid){
                $v->le=$le;
                $array[]=$v;
                self::fl($data,$v->id,$le+1);
            }
        }
        return $array;
    }

}