TypeError: __init__() 得到了一个意外的关键字参数“很多”

Question

尝试使用通用视图返回查询集时，出现错误

TypeError: init() 得到了一个意外的关键字参数 'many'

我无法理解此错误的来源，因为它似乎来自内部库。我不知道为什么这个错误源于 create API 工作正常。

完成 StackTrace

System check identified 1 issue (0 silenced).
July 16, 2018 - 13:25:43
Django version 1.11.7, using settings 'BirthdayPostStash.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
<QuerySet [<Photos: 1>, <Photos: 2>, <Photos: 3>, <Photos: 4>, <Photos: 5>, <Photos: 6>, <Photos: 7>, <Photos: 8>, <Photos: 9>, <Photos: 10>, <Photos: 11>, <Photos: 12>]>
Internal Server Error: /photos/list-photo/
Traceback (most recent call last):
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/django/core/handlers/exception.py", line 41, in inner
    response = get_response(request)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/django/views/generic/base.py", line 68, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/views.py", line 489, in dispatch
    response = self.handle_exception(exc)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/views.py", line 449, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/views.py", line 486, in dispatch
    response = handler(request, *args, **kwargs)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/generics.py", line 201, in get
    return self.list(request, *args, **kwargs)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/mixins.py", line 44, in list
    serializer = self.get_serializer(page, many=True)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/generics.py", line 112, in get_serializer
    return serializer_class(*args, **kwargs)
  File "/home/t2b/env/bpstash/local/lib/python2.7/site-packages/rest_framework/fields.py", line 1774, in __init__
    super(ModelField, self).__init__(**kwargs)
TypeError: __init__() got an unexpected keyword argument 'many'
[16/Jul/2018 13:25:45] "GET /photos/list-photo/ HTTP/1.1" 500 111194

models.py

class Photos(models.Model):

owner = models.ForeignKey(User, related_name="photos_owner")
photo = models.ImageField(upload_to=get_image_path, blank=True)
participants = models.ManyToManyField(
              Person,
              related_name="photos_participants",
              null=True,
              blank=True)

views.py

class ListPhoto(generics.ListAPIView):
permission_classes = (permissions.IsAuthenticated,)
serializer_class = PhotoPublicSerializer
model = Photos

def get_queryset(self):
    return self.model.objects.all()

serializer.py

class PhotoPublicSerializer(serializers.ModelField):
participants = PersonPublicSerializer(read_only=True)

class Meta:
    model = Photos
    fields = '__all__'

personserializer.py

class PersonPublicSerializer(serializers.ModelSerializer):
    class Meta:
        model = Person
        fields = '__all__'

Answer 1

看来是打错字了。

class PhotoPublicSerializer(serializers.ModelField):
class PhotoPublicSerializer(serializers.ModelSerializer):

Answer 2

当serializer_class 指向模型而不是ModelSerializer 时，我遇到了这个问题

Answer 3

问题是由以下行引起的：

participants = PersonPublicSerializer(many=True)

调查，可以看出：

• PersonPublicSerializer 是从serializers.ModelField 扩展而来的class

• serializers.ModelField 是从serializers.Field 扩展而来的class

• Field，在初始化时，接受以下参数之一（及其默认值）：

  • read_only=False
  • write_only=False
  • required=None
  • default=empty
  • initial=empty
  • source=None
  • label=None
  • help_text=None
  • style=None
  • error_messages=None
  • validators=None
  • allow_null=False

• 反过来ModelField 期望（即必须具有）model_field 参数，并且可以另外使用Field 的任何一个参数调用。

现在，如您所见，ModelField 和 Field 在其声明中都没有 many 参数。

所以，要么PersonPublicSerializer 没有正确声明，应该实现many arg，要么你依赖于误解。

来源：Field's source code