thinkphp5.1 paginate分页方法 修改data里面的值

$resource = Db::table($sql)->paginate(10)->each(function ($item) {
    if(empty($item['cover']) && $item['related_id'] != 0){
        $tmpResource = ResourceModel::where('id',$item['related_id'])->field('cover')->find();
        $item['cover'] = $tmpResource['cover'];
    }
    return $item;
});