解决thinkphp5.0中通过paginate查询出来的数据加不了自定义字段的问题

        $res = db("admin")->alias("a")->join("auth_group_access g","a.id=g.uid")->paginate(2);
        $tempArr = $res->all();
        foreach ($tempArr as $k => $v){
            $groupName = db("auth_group")->field("title")->where("id",$v['group_id'])->find();
            $v['groupName'] = $groupName['title'];
            $res[$k] = $v;
        }