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Django序列化程序:如何验证模型实例?

django-serializer django-rest-framework django python

saran3h · 技术社区 · 7 年前

我有一个相当一般的场景,在这个场景中我调用api,它只是在我的模型对象中设置一个字段并保存它(假设记录已经存在并且正在更新)。但是,我需要在保存之前验证这个模型对象。

api.py公司

@detail_route(methods=['POST'], url_path='submit-draft')
def submit_draft(self, request, *args, **kwargs):
    booking = self.get_object()

    # serializer with custom validations.
    serializer = self.get_serializer(booking)
    serializer.is_valid(raise_exception=True)

    booking.submit_draft(by=request.user)
    booking.save()

    data = serializers.BookingDetailSerializer(booking, context={'request': request}).data

    return response.Ok(data)

序列化程序.py

class BookingCreateUpdateSerializer(serializers.ModelSerializer):
    date = serializers.CharField()

    duration = serializers.IntegerField(required=True, )

    created_by = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault(), )

    modified_by = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault(), )
    ....

    class Meta:
    model = models.Booking
        fields = [
        'title',
        'date',
        'duration',
        'client',
        'created_by',
        'modified_by',
        ....
    ]

但是,我得到一个错误:

AssertionError: Cannot call '.is_valid()' as no 'data=' keyword argument was passed when instantiating the serializer instance.

2 回复 | 直到 6 年前

Enthusiast Martin 7 年前

可以使用序列化程序:

1) 将对象序列化为字典。在这种情况下,您不需要调用is\u valid,因为对象已经创建,并且它具有有效值。因此,您可以执行以下操作:

serializer = BookingCreateUpdateSerializer(booking)

return Response(serializer.data)

serializer = BookingCreateUpdateSerializer(data=input_dict)
serializer.is_valid()
serializer.save()

可以执行以下操作以使用序列化程序更新实例:

serializer = BookingCreateUpdateSerializer(booking, data=input_data_to_update, partial=True)
serializer.is_valid()

instance = serializer.save()

# and serialize the updated instance for response using another serializer
output_data = BookingDetailSerializer(instance).data

saran3h 6 年前

在花了将近一天的时间挠头之后,这终于奏效了。

api.py公司

@detail_route(methods=['POST'], url_path='submit-draft')
def submit_draft(self, request, *args, **kwargs):
    # Step1. Get current model instance.
    booking = self.get_object()

    # Step2. Serialize the model instance using same serializer as in Step5.
    booking_data = serializers.BookingDetailSerializer(booking, context={'request': 
    request}).data

    # Step3. Deserialize the data from Step2 (using `BookingCreateUpdateSerializer` serializer 
    as mentioned in description and check for validations.
    serializer = self.get_serializer(data=booking_data)
    serializer.is_valid(raise_exception=True)       

    # Step4. If no validation error, set the required field and save the instance.
    booking.submit_draft(by=request.user)
    booking.save()

    # Step5. Return response.
    data = serializers.BookingDetailSerializer(booking, context={'request': request}).data

    return response.Ok(data)

今天我学到了更多关于连载器的知识。我们可以将模型实例传递到不同的序列化程序中,并根据需要更改其形状。