在 Django REST 框架序列化程序中动态排除或包含字段

Question

我在 Django REST 框架中有一个序列化器，定义如下：

class QuestionSerializer(serializers.Serializer):
    id = serializers.CharField()
    question_text = QuestionTextSerializer()
    topic = TopicSerializer()

现在我有两个使用上述序列化程序的 API 视图：

class QuestionWithTopicView(generics.RetrieveAPIView):
    # I wish to include all three fields - id, question_text
    # and topic in this API.
    serializer_class = QuestionSerializer

class QuestionWithoutTopicView(generics.RetrieveAPIView):
    # I want to exclude topic in this API.
    serializer_class = ExamHistorySerializer

一种解决方案是编写两个不同的序列化程序。但是必须有一个更简单的解决方案来有条件地从给定的序列化程序中排除一个字段。

Answer 1

你试过这个技巧吗

class QuestionSerializer(serializers.Serializer):
    def __init__(self, *args, **kwargs):
        remove_fields = kwargs.pop('remove_fields', None)
        super(QuestionSerializer, self).__init__(*args, **kwargs)

        if remove_fields:
            # for multiple fields in a list
            for field_name in remove_fields:
                self.fields.pop(field_name)

class QuestionWithoutTopicView(generics.RetrieveAPIView):
        serializer_class = QuestionSerializer(remove_fields=['field_to_remove1' 'field_to_remove2'])

如果没有，请尝试一下。

Answer 2

创建一个新的序列化程序是可行的方法。通过有条件地删除序列化程序中的字段，您会增加额外的复杂性并使您的代码更难快速诊断。您应该尽量避免混合单个类的职责。

遵循基本的面向对象设计原则是必经之路。

QuestionWithTopicView 是一个 QuestionWithoutTopicView 但有一个附加字段。

class QuestionSerializer(serializers.Serializer):
        id = serializers.CharField()
        question_text = QuestionTextSerializer()
        topic = TopicSerializer()

class TopicQuestionSerializer(QuestionSerializer):
       topic = TopicSerializer()

Answer 3

将above answer 扩展为更通用的

class QuestionSerializer(serializers.Serializer):
    def __init__(self, *args, **kwargs):
        fields = kwargs.pop('fields', None)
        super(QuestionSerializer, self).__init__(*args, **kwargs)
        if fields is not None:
            allowed = set(fields.split(','))
            existing = set(self.fields)
            for field_name in existing - allowed:
                self.fields.pop(field_name)

class QuestionWithoutTopicView(generics.RetrieveAPIView):
    def get_serializer(self, *args, **kwargs):
        kwargs['context'] = self.get_serializer_context()
        fields = self.request.GET.get('display')
        serializer_class = self.get_serializer_class()
        return serializer_class(fields=fields,*args, **kwargs)
    def get_serializer_class(self):
        return QuestionSerializer
    

现在我们可以给出一个名为 display 的查询参数来输出任何自定义的显示格式http://localhost:8000/questions?display=param1,param2

Answer 4

可以设置Meta的fields和exclude属性

这是一个例子：

class DynamicFieldsModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        exclude = ['id', 'email', 'mobile']

    def __init__(self, *args, **kwargs):
        super(DynamicFieldsModelSerializer, self).__init__(*args, **kwargs)
        #  @note: For example based on user,  we will send different fields
        if self.context['request'].user == self.instance.user:
            # Or set self.Meta.fields = ['first_name', 'last_name', 'email', 'mobile',]
            self.Meta.exclude = ['id']