python - 如何使用 Django REST 序列化程序对保留键进行验证？

Question

这可能是一个简单的问题，需要眨眼解决方法。但我无法完成它。我现在正在创建 webhook 端点。并停留在 serializer 类我的类无法使用 from 作为类属性

Python 3.6.4
Django==1.11.9
djangorest==3.7.7

@pytest.fixture
def like_object():
    """LIKE object response from Facebook"""
    return {
        "object": "page",
        "entry": [{
            "changes": [{
                "field": "feed",
                "value": {
                    "item": "reaction",
                    "verb": "add",
                    "reaction_type": "like",
                    "created_time": 1516183830,
                    "post_id": "1331351323541869_1844740022202994",
                    "from": {
                        "name": "Elcoie Sieve",
                        "id": "1639217166122728"
                    },
                    "parent_id": "1331351323541869_1844740022202994"
                }
            }],
            "time": 1516183830, "id": "1331351323541869"
        }]
    }

序列化器.py

class FacebookReactionSerializer(serializers.Serializer):
    """
    value serializer the inner most of the payload
    """
    item = serializers.CharField()
    verb = serializers.CharField()
    reaction_type = serializers.CharField()
    created_time = serializers.IntegerField(
        validators=[MinValueValidator(0), MaxValueValidator(4086831600)]
    )  # Limit the maximum epoch to 2099 July 4th 7:00AM
    post_id = serializers.CharField(max_length=40)
    from = FromSerializer()
    parent_id = serializers.CharField()

    def validate(self, attrs):
        """
        `from` is a python reserved word the add _ to distinguish it from them
        :param attrs:
        :return:
        """
        from_ = attrs.get('from')
        pass

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

尝试:

ffrom = FromSerializer(source='from')

不起作用

尝试2:

class FacebookReactionSerializer(serializers.Serializer):
    """
    value serializer the inner most of the payload
    """
    item = serializers.CharField()
    verb = serializers.CharField()
    reaction_type = serializers.CharField()
    created_time = serializers.IntegerField(
        validators=[MinValueValidator(0), MaxValueValidator(4086831600)]
    )  # Limit the maximum epoch to 2099 July 4th 7:00AM
    post_id = serializers.CharField(max_length=40)
    from_key = FromSerializer()
    parent_id = serializers.CharField()

    def to_representation(self, instance):
        """
        https://stackoverflow.com/questions/47630356/using-the-reserved-word-class-as-field-name-in-django-and-django-rest-framewor
        :param instance:
        :return:
        """
        data = super().to_representation(instance)
        keys = list(data.keys())
        keys.insert(keys.index('from_key'), 'from')
        keys.remove('from_key')
        from_key = data.pop('from_key')
        data.update({'from': from_key})
        response = OrderedDict((k, data[k]) for k in keys)
        return response

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

测试用例失败这里是断点

(Pdb) serializer
FacebookReactionSerializer(data={'item': 'reaction', 'verb': 'add', 'reaction_type': 'like', 'created_time': 1516183830, 'post_id': '1331351323541869_1844740022202994', 'from': {'name': 'Krittuch Onnom', 'id': '1639217166122728'}, 'parent_id': '1331351323541869_1844740022202994'}):
    item = CharField()
    verb = CharField()
    reaction_type = CharField()
    created_time = IntegerField(validators=[<rest_framework.compat.MinValueValidator object>, <rest_framework.compat.MaxValueValidator object>])
    post_id = CharField(max_length=40)
    from_key = FromSerializer():
        name = CharField()
        id = CharField()
    parent_id = CharField()
(Pdb) serializer.errors
*** AssertionError: You must call `.is_valid()` before accessing `.errors`.
(Pdb) serializer.is_valid()
False
(Pdb) serializer.errors
{'from_key': ['This field is required.']}

尝试3:
还要添加 `._declared_fields['from_key']

class FacebookReactionSerializer(serializers.Serializer):
    item = serializers.CharField()
    verb = serializers.CharField()
    reaction_type = serializers.CharField()
    created_time = serializers.IntegerField(
        validators=[MinValueValidator(0), MaxValueValidator(4086831600)]
    )  # Limit the maximum epoch to 2099 July 4th 7:00AM
    post_id = serializers.CharField(max_length=40)
    from_key = FromSerializer()
    parent_id = serializers.CharField()

    def to_representation(self, instance):
        data = super().to_representation(instance)
        keys = list(data.keys())
        keys.insert(keys.index('from_key'), 'from')
        keys.remove('from_key')
        from_key = data.pop('from_key')
        data.update({'from': from_key})
        response = OrderedDict((k, data[k]) for k in keys)
        return response

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass

FacebookReactionSerializer._declared_fields["from"] = serializers.CharField(source="from_key")

调试线:

(Pdb) serializer.is_valid()
False
(Pdb) serializer.errors
{'from_key': ['This field is required.'], 'from': ['Not a valid string.']}

我已经很接近了，但还不够

尝试4.1:

不工作。保持同样的错误。 from_key 仍然保留。我是从 child 序列化器编写的。我必须使用 FromSerializer 而不是 CharField。

    class FacebookReactionSerializer(serializers.Serializer):
    """
    value serializer the inner most of the payload
    """
    item = serializers.CharField()
    verb = serializers.CharField()
    reaction_type = serializers.CharField()
    created_time = serializers.IntegerField(
        validators=[MinValueValidator(0), MaxValueValidator(4086831600)]
    )  # Limit the maximum epoch to 2099 July 4th 7:00AM
    post_id = serializers.CharField(max_length=40)
    from_key = FromSerializer()
    parent_id = serializers.CharField()

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass


FacebookReactionSerializer._declared_fields["from"] = FromSerializer(source="from_key")

我现在可以添加 from 作为 key 。但它不会从验证逻辑中删除 from_key

(Pdb) serializer
FacebookReactionSerializer(data={'item': 'reaction', 'verb': 'add', 'reaction_type': 'like', 'created_time': 1516183830, 'post_id': '1331351323541869_1844740022202994', 'from': {'name': 'Krittuch Onnom', 'id': '1639217166122728'}, 'parent_id': '1331351323541869_1844740022202994'}):
    item = CharField()
    verb = CharField()
    reaction_type = CharField()
    created_time = IntegerField(validators=[<rest_framework.compat.MinValueValidator object>, <rest_framework.compat.MaxValueValidator object>])
    post_id = CharField(max_length=40)
    from_key = FromSerializer():
        name = CharField()
        id = CharField()
    parent_id = CharField()
    from = FromSerializer(source='from_key'):
        name = CharField()
        id = CharField()
(Pdb) serializer.is_valid()
False
(Pdb) serializer.errors
{'from_key': ['This field is required.']}

问题:
当 from(保留字)是 key 并且该键是 python 类属性时，您的解决方法是什么？

Answer 1

@cezar 非常感谢!
解决办法就是这么简单!我一开始很困惑。因为给定的解决方案使用的是 ModelSerializer，所以您必须放置字段并与模型属性耦合。

在我的示例中是简单的Serializer，我不需要它们中的任何一个。

从现在开始，我将通过 Serializer 类来解决此类问题

class FacebookReactionSerializer(serializers.Serializer):
    """
    value serializer the inner most of the payload
    """
    item = serializers.CharField()
    verb = serializers.CharField()
    reaction_type = serializers.CharField()
    created_time = serializers.IntegerField(
        validators=[MinValueValidator(0), MaxValueValidator(4086831600)]
    )  # Limit the maximum epoch to 2099 July 4th 7:00AM
    post_id = serializers.CharField(max_length=40)
    parent_id = serializers.CharField()

    def create(self, validated_data):
        pass

    def update(self, instance, validated_data):
        pass


FacebookReactionSerializer._declared_fields["from"] = FromSerializer()

这是我的调试行

(Pdb) serializer
FacebookReactionSerializer(data={'item': 'reaction', 'verb': 'add', 'reaction_type': 'like', 'created_time': 1516183830, 'post_id': '1331351323541869_1844740022202994', 'from': {'name': 'Krittuch Onnom', 'id': '1639217166122728'}, 'parent_id': '1331351323541869_1844740022202994'}):
    item = CharField()
    verb = CharField()
    reaction_type = CharField()
    created_time = IntegerField(validators=[<rest_framework.compat.MinValueValidator object>, <rest_framework.compat.MaxValueValidator object>])
    post_id = CharField(max_length=40)
    parent_id = CharField()
    from = FromSerializer():
        name = CharField()
        id = CharField()
(Pdb) serializer.is_valid()
True