Question

我有一个稍微复杂的APIView，这使得我无法使用通用ListAPIView来返回查询集。但即使我设置many=True，我也无法使用ModelSerializer简单地序列化一个简单的Django查询集。

不知怎的，这不起作用：

serializers.py：

class SomeModelSerializer(serializers.ModelSerializer):

    class Meta:
        model = SomeModel
        fields = ['some_field']

views.py：

from rest_framework.response import Response

class SomeAPIView(APIView):
    serializer_class = SomeInputSerializer

    def post(self, request, format=None):
        serializer = self.serializer_class(data=request.data)
        if serializer.is_valid():
            # first some business logic, then return results
            results = SomeModel.objects.all()
            output_serializer = SomeModelSerializer(results, many=True)
            return Response(output_serializer.data)

我所得到的只是：'ListSerializer' object is not iterable。

我做错了什么？

错误：

/projectfolder/venv/lib/python2.7/site-packages/django/template/defaulttags.py in render
            try:
                values = self.sequence.resolve(context, True)
            except VariableDoesNotExist:
                values = []
            if values is None:
                values = []
            if not hasattr(values, '__len__'):
                values = list(values) ...
            len_values = len(values)
            if len_values < 1:
                return self.nodelist_empty.render(context)
            nodelist = []
            if self.is_reversed:
                values = reversed(values)

values = list(values)似乎应对错误负责

Answer 1

以下是使用as_view（）网址的作品：

 class ListCreateMemberViewSet(generics.ListCreateAPIView):
        """
        API endpoint that allows multiple members to be created.
        """
        queryset = Member.objects.none()
        serializer_class = MemberSerializer

    def get_queryset(self):
         queryset = Member.objects.all()
         return queryset

    def create(self, request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data, many=isinstance(request.data, list))
        serializer.is_valid(raise_exception=True)
        self.perform_create(serializer)
        results = Member.objects.all()
        output_serializer = MemberSerializer(results, many=True)
        data = output_serializer.data[:]
        return Response(data)

Answer 2

遇到了和你一样的问题。我找到了一个快速而简单的错误修复：将序列化数据复制到一个新数组并返回。

results = SomeModel.objects.all()

output_serializer = SomeModelSerializer(results, many=True)    
data = output_serializer.data[:]

return Response(data)

这对我有用，希望对你也有用。

Answer 3

该错误是尝试直接在序列化程序上运行list的结果。

例如，这将引发以上异常：

results = Member.objects.all()
output_serializer = MemberSerializer(results, many=True)
all_results = list(output_serializer) # this line here
all_results += output_serializer  # or this line here

这不会（区别是我们列出的是output_serializer.data而不是output_serializer）：

results = Member.objects.all()
output_serializer = MemberSerializer(results, many=True)
all_results = list(output_serializer.data)
all_results += output_serializer.data

我觉得在原始问题中，示例代码与实际代码并非100％匹配。

＆＃39; ListSerializer＆＃39;使用Django Rest Framework序列化查询集时

3 个答案: