Django Rest Framework，将对象添加到request.data中，然后调用serializer is_valid（） [英] Django Rest Framework, add object to request.data and then call serializer is_valid()

问题描述

我想知道哪个是最好的解决方法，我有一个这样的嵌套序列化：

serializers.py：

  class PaymentMethodSerializer（serializers.ModelSerializer）：
 
 data = serializers.JSONField（）
 payment_type = PaymentTypeSerializer（required = F $）
  

然后，视图看起来像这样：

  class PaymentMethodView（APIView）：
 def put（self，request，id）：
 
 try：
 payment_method = PaymentMethod.objects.get（id = id）
除了ObjectDoesNotExist：
返回响应（No PaymentMethod with the id，status = status.HTTP_404_NOT_FOUND）
 
 payment_method_serialized = PaymentMethodSerializer instance = payment_method，data = request.data）
 payment_type = request.data.get（payment_type，None）
 
如果payment_type：
 try：
 payment_met hod_type = PaymentType.objects.get（id = payment_type）
除了ObjectDoesNotExist：
 payment_method_type =无
其他：
 payment_method_type =无
 
＃现在，调用is_valid（）
如果payment_method_serialized.is_valid（）：
 payment_method_serialized.save（payment_type = payment_method_type）
返回响应（payment_method_serialized.data，status = status.HTTP_200_OK）
  

is_valid（）返回False，此错误：

  {payment_type：{non_field_errors：[无效的数据。预期一个字典，但有int。]}} 
  

我明白了，我给serializer a pk 。但是我不想创建一个带有 PrimaryKeyRelatedField 而不是嵌套关系的新的序列化为此，如何获得与 pk 相对应的 PaymentType ，然后将该对象添加到 request.data 字典，以便 is_valid 不会失败？这是解决这个问题的最好方法吗？

解决方案

假设 payment_type 是 ForeignKey field在 PaymentMethod 模型中， null = True 因为 required = False 。

如果你只提供一个 pk ，所以你不需要这个字段串行器，你可以写入字段，像所有其他字段。

  class PaymentMethodSerializer（serializers.ModelSerializer）：
 
 data = serializers.JSONField（）
 
 class Meta：
 model = PaymentMethod 
 fields =（'data'，'payment_type'）
  

它将接受 pk 或无。如果要为您的 PaymentType 模型提供特殊表示，您可以覆盖 to_representation（）方法。

  class PaymentMethodSerializer（serializers.ModelSerializer）：
 
 ... 
 def to_representation（self，instance ）
 representation = super（PaymentMethodSerializer，self）.to_representation（instance）
 representation ['payment_type'] = PaymentTypeSerializer（instance.payment_type）.data 
 return representation 
  

现在，它将使用PaymentTypeSerializer表示相关的 PaymentType 模型。 >
您可以在序列化程序中移动 payment_type 验证。覆盖 to_internal_value ，检查提供的 PaymentType pk，如果错误则抛出异常，然后在视图中捕获该异常。 / p>


I'm wondering which is the best way to solve this, I have a nested serializer like this:

serializers.py:

class PaymentMethodSerializer(serializers.ModelSerializer):

    data = serializers.JSONField()
    payment_type = PaymentTypeSerializer(required=False)

Then, the view looks something like this:

class PaymentMethodView(APIView):
    def put(self, request, id):

        try:
            payment_method = PaymentMethod.objects.get(id=id)
        except ObjectDoesNotExist:
            return Response("No PaymentMethod with that id", status=status.HTTP_404_NOT_FOUND)

        payment_method_serialized = PaymentMethodSerializer(instance=payment_method, data=request.data)
        payment_type = request.data.get("payment_type", None)

        if payment_type:
            try:
                payment_method_type = PaymentType.objects.get(id=payment_type)
            except ObjectDoesNotExist:
                payment_method_type = None
        else:
            payment_method_type = None

    # Now, call is_valid()
        if payment_method_serialized.is_valid():
            payment_method_serialized.save(payment_type=payment_method_type)
            return Response(payment_method_serialized.data, status=status.HTTP_200_OK)

is_valid() returns False and this error:

{"payment_type":{"non_field_errors":["Invalid data. Expected a dictionary, but got int."]}}

I understand it, I'm giving the serializer a pk. However I don't want to create a new serializer with a PrimaryKeyRelatedField instead of the nested relationship just for this. How can I get the PaymentType that corresponds to that pk and then add that object to the request.data dictionary so that is_valid doesn't fail? is it the best way to solve this?

解决方案

Suppose payment_type is ForeignKey field in a PaymentMethod model, with null=True because of required=False.
If you provide only a pk so you don't need serializer for it field, you can just write in fields, like all other fields.

class PaymentMethodSerializer(serializers.ModelSerializer):

    data = serializers.JSONField()

    class Meta:
        model = PaymentMethod
        fields = ('data', 'payment_type')

It will accept pk or None. If you want to provide special representation for your PaymentType model, you can override a to_representation() method.

class PaymentMethodSerializer(serializers.ModelSerializer):

    ...
    def to_representation(self, instance):
        representation = super(PaymentMethodSerializer, self).to_representation(instance)
        representation['payment_type'] = PaymentTypeSerializer(instance.payment_type).data
        return representation

Now it will use PaymentTypeSerializer for representation of related PaymentType model.
You can move you payment_type validation in a serializer though. Override to_internal_value, check provided PaymentType pk and throw an exception if it wrong and then catch that exception in a view.

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