序列化器验证 - TypeError ...“UniqueTogetherValidator”对象不可迭代

Question

我有一个名为“following”的模型，一个用户可以使用 Django rest 框架来关注另一个用户。我正在尝试实施验证，以便您不能两次关注某人，并尝试使用内置的 UniqueTogetherValidator。

这是我的models.py的相关部分

class Following(models.Model):
    user = models.ForeignKey('User', related_name='user', on_delete=models.CASCADE)
    follower = models.ForeignKey('User', related_name='follower', on_delete=models.CASCADE)

还有serializers.py：

class FollowingSerializer(serializers.HyperlinkedModelSerializer):
    user = serializers.CharField(source='user.username')
    follower = serializers.CharField(source='follower.username')

    class Meta:
        model = Following
        fields = ['user', 'follower']

        validators = UniqueTogetherValidator(
            queryset = Following.objects.all(),
            fields = ['user', 'follower'],
            message = "You are already following that person!"
        )

我有一些现有数据：

HTTP 200 OK
Allow: GET, POST, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "count": 2,
    "next": null,
    "previous": null,
    "results": [
        {
            "user": "mike",
            "follower": "chelsea"
        },
        {
            "user": "mike",
            "follower": "chloe"
        }
    ]
}

当我尝试使用 API 接口添加任何新的以下对象时，我收到此错误：

TypeError at /followings/
'UniqueTogetherValidator' object is not iterable
Request Method: POST
Request URL:    http://127.0.0.1:8000/followings/
Django Version: 3.0.5
Exception Type: TypeError
Exception Value:    
'UniqueTogetherValidator' object is not iterable
...

我哪里做错了？提前致谢！

Answer 1

正如https://www.django-rest-framework.org/api-guide/validators/#uniquetogethervalidator 中提到的，Meta 下的validators 变量应该是一个列表，

你的代码应该是

class FollowingSerializer(serializers.HyperlinkedModelSerializer):
user = serializers.CharField(source='user.username')
follower = serializers.CharField(source='follower.username')

class Meta:
    model = Following
    fields = ['user', 'follower']

    validators = [
        UniqueTogetherValidator(
            queryset = Following.objects.all(),
            fields = ['user', 'follower'],
            message = "You are already following that person!"
        )
    ]