Django - AttributeError: 'NoneType' object has no attribute 'method'

Question

I noticed that when I use DRF documentation I get error AttributeError: 'NoneType' object has no attribute 'method' and this is associated with this line if self.request.method == 'POST' Any ideas how can I solve it?

views.py:

@permission_classes([UserPermission])
class UserObject(GenericAPIView):

    def get_serializer_class(self):

        if self.request.method == 'POST':
            return ObjectPostSerializer
        return ObjectSerializer

    def post(self, request, user_id):

        serializer = ObjectSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save(user_id=user_id)
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def get(self, request, user_id):

        try:
            object = Object.objects.filter(user=user_id)
        except Object.DoesNotExist:
            return Response(status=status.HTTP_404_NOT_FOUND)
        serializer = ObjectSerializer(object, many=True)
        return Response(serializer.data)

    def put(self, request, user_id):

        try:
            object = Object.objects.get(user=user_id)
        except Object.DoesNotExist:
            return Response(status=status.HTTP_404_NOT_FOUND)
        serializer = ObjectSerializer(object, data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def delete(self, request, user_id):

        try:
            object = Object.objects.filter(user=user_id)
        except Object.DoesNotExist:
            return Response(status=status.HTTP_404_NOT_FOUND)
        object.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)

Traceback without self:

django_1  |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner
django_1  |     response = get_response(request)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response
django_1  |     response = self.process_exception_by_middleware(e, request)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response
django_1  |     response = wrapped_callback(request, *callback_args, **callback_kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
django_1  |     return view_func(*args, **kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py", line 68, in view
django_1  |     return self.dispatch(request, *args, **kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 489, in dispatch
django_1  |     response = self.handle_exception(exc)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 449, in handle_exception
django_1  |     self.raise_uncaught_exception(exc)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 486, in dispatch
django_1  |     response = handler(request, *args, **kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/views.py", line 31, in get
django_1  |     schema = self.schema_generator.get_schema(request, self.public)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/generators.py", line 279, in get_schema
django_1  |     links = self.get_links(None if public else request)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/generators.py", line 317, in get_links
django_1  |     link = view.schema.get_link(path, method, base_url=self.url)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/inspectors.py", line 167, in get_link
django_1  |     fields += self.get_serializer_fields(path, method)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/inspectors.py", line 290, in get_serializer_fields
django_1  |     serializer = view.get_serializer()
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/generics.py", line 110, in get_serializer
django_1  |     serializer_class = self.get_serializer_class()
django_1  |   File "/code/backend/views.py", line 173, in get_serializer_class
django_1  |     if request.method == 'POST':
django_1  | NameError: name 'request' is not defined

Traceback with self:

django_1  | Traceback (most recent call last):
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py", line 41, in inner
django_1  |     response = get_response(request)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 187, in _get_response
django_1  |     response = self.process_exception_by_middleware(e, request)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 185, in _get_response
django_1  |     response = wrapped_callback(request, *callback_args, **callback_kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
django_1  |     return view_func(*args, **kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py", line 68, in view
django_1  |     return self.dispatch(request, *args, **kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 489, in dispatch
django_1  |     response = self.handle_exception(exc)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 449, in handle_exception
django_1  |     self.raise_uncaught_exception(exc)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/views.py", line 486, in dispatch
django_1  |     response = handler(request, *args, **kwargs)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/views.py", line 31, in get
django_1  |     schema = self.schema_generator.get_schema(request, self.public)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/generators.py", line 279, in get_schema
django_1  |     links = self.get_links(None if public else request)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/generators.py", line 317, in get_links
django_1  |     link = view.schema.get_link(path, method, base_url=self.url)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/inspectors.py", line 167, in get_link
django_1  |     fields += self.get_serializer_fields(path, method)
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/schemas/inspectors.py", line 290, in get_serializer_fields
django_1  |     serializer = view.get_serializer()
django_1  |   File "/usr/local/lib/python3.6/site-packages/rest_framework/generics.py", line 110, in get_serializer
django_1  |     serializer_class = self.get_serializer_class()
django_1  |   File "/code/backend/views.py", line 173, in get_serializer_class
django_1  |     if self.request.method == 'POST':
django_1  | AttributeError: 'NoneType' object has no attribute 'method'

@AditiaPratama Without self I get `name 'request' is not defined` — , Oct 30 '17 at 09:46
`GenericAPIView` has property `request` if you call it as view, but what are you do? go by url or create some tests — Brown Bear, Oct 30 '17 at 09:55
Your method looks ok (`*args, **kwargs` is not needed, but that shouldn't make any difference). Can you edit the question and add the full traceback? — Håken Lid, Oct 30 '17 at 09:56
@BearBrown I call is as view `url(r'^users/(?P[0-9]+)/objects$', views.UserObject.as_view())` — , Oct 30 '17 at 10:00
Can you have a look at the answer here? It looks pretty much the same problem https://stackoverflow.com/questions/38281651/django-rest-framework-self-context-doesnt-have-request-attribute — ChatterOne, Oct 30 '17 at 10:00
Do you overrides the constructor or any other method for this class? If so, do you call the parent method? — luc, Oct 30 '17 at 10:03
@JohnSmith I think, we don't need the model but you should put the full code of the view — luc, Oct 30 '17 at 10:14
From the traceback, it seems you are using a `@csrf_exempt` view decorator? Where's that? — Håken Lid, Oct 30 '17 at 10:15
@HåkenLid I don't use `@csrf_exempt` decorator in my `views.py`. I have in middleware `'django.middleware.csrf.CsrfViewMiddleware',`. — , Oct 30 '17 at 10:22
You're not even calling `get_serializer` method to invoke the `get_serializer_class` method — Sachin, Oct 30 '17 at 10:23
@SachinKukreja But it is working properly. There is only a problem with DRF doc. For instance in Swagger I don't have any problem with it. — , Oct 30 '17 at 10:24
@JohnSmith Your code is strange because it looks that the traceback doesn't correspond to it. I agree with @SachinKukreja , `get_serializer_class`shouldn't be called here. — luc, Oct 30 '17 at 10:29
@luc So how it should be done to have separated serializer `ObjectPostSerializer` for POST method and for others `ObjectSerializer`? — , Oct 30 '17 at 10:35
Since you're using GenericAPIView without any mixin classes, you have to override the get, post, etc. methods, through which you know that which request method it is. — Sachin, Oct 30 '17 at 10:38
@SachinKukreja can you show me how it should be done in my GenericAPIView? — , Oct 30 '17 at 10:41

score 0 · Answer 1 · answered Oct 30 '17 at 10:39

You are using a function decorator with a class based view. This will cause undefined behaviour down the line, since the class instance will not be initialized correctly.

@permission_classes([UserPermission])
class UserObject(GenericAPIView):
    ...

Instead use a class property.

class UserObject(GenericAPIView):
    permission_classes = [UserPermission]

Docs: http://www.django-rest-framework.org/api-guide/permissions/#setting-the-permission-policy

Sachin · Accepted Answer · 2017-10-30T11:24:29.343

0

Remove the get_serializer_class method and you're good to go.

Modifications:

class UserObject(GenericAPIView):
    serializer_class = ObjectSerializer

    def post(self, request, user_id):
        # this is here you change the serializer.
        serializer = ObjectPostSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save(user_id=user_id)
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

edited Oct 30 '17 at 11:24

answered Oct 30 '17 at 10:57

Sachin

3,576
1
15
24

I tried in this way before creating `get_serializer_class` and I was getting `'UserObject' should either include a serializer_class attribute, or override the get_serializer_class() method.` – Oct 30 '17 at 11:08

score 0 · Answer 3 · answered Jun 03 '22 at 09:55

0

I would separate the view to CreateAPIView and RetreiveAPIView and use different serializers for each of them.

answered Jun 03 '22 at 09:55

Fedya Grab

36
6

Django - AttributeError: 'NoneType' object has no attribute 'method'

3 Answers3