Laravel关联模型中过滤结果为空的结果集(has和with区别)

首先看代码：

$userCoupons = UserCoupons::with(['coupon' => function($query) use($groupId){
    return $query->select('id', 'group_id', 'cover', 'group_number', 'group_cover')->where([
        'group_id' => $groupId,
    ]);
}])
// 更多查询省略...$userCoupons = UserCoupons::with(['cou