Laravel 的Get参数加入sql语句

//显示清单列表
    public function getIndex($user_id = null)
    {
        //读取当前所有设备
        $checklists = DB::table(‘check_lists‘)
            ->leftJoin(‘users‘, ‘check_lists.user_id‘, ‘=‘, ‘users.id‘)
            ->select(‘check_lists.*‘, ‘users.email as user_name‘)

            ->when(!!$user_id, function($q) use ($user_id){
                return $q->where(‘user_id‘, $user_id);
            })

            ->paginate(10);
        return view(‘admin.checklists.index‘,compact(‘checklists‘));
    }