Django viewset has not attribute 'get_extra_actions'

Question

I am working with Django for a first time and I'm trying to build an API and I am following some tutorials and examples and it works right, but I am running the project now in a Raspberry Pi after install all the requirements and the project is failing with the following error:

    Performing system checks...

Unhandled exception in thread started by <function check_errors.<locals>.wrapper at 0xb547adb0>
Traceback (most recent call last):
  File "/home/pi/.local/lib/python3.5/site-packages/django/utils/autoreload.py", line 225, in wrapper
    fn(*args, **kwargs)
  File "/home/pi/.local/lib/python3.5/site-packages/django/core/management/commands/runserver.py", line 120, in inner_run
    self.check(display_num_errors=True)
  File "/home/pi/.local/lib/python3.5/site-packages/django/core/management/base.py", line 364, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/pi/.local/lib/python3.5/site-packages/django/core/management/base.py", line 351, in _run_checks
    return checks.run_checks(**kwargs)
  File "/home/pi/.local/lib/python3.5/site-packages/django/core/checks/registry.py", line 73, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/pi/.local/lib/python3.5/site-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/home/pi/.local/lib/python3.5/site-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/home/pi/.local/lib/python3.5/site-packages/django/urls/resolvers.py", line 397, in check
    for pattern in self.url_patterns:
  File "/home/pi/.local/lib/python3.5/site-packages/django/utils/functional.py", line 36, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/pi/.local/lib/python3.5/site-packages/django/urls/resolvers.py", line 536, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/home/pi/.local/lib/python3.5/site-packages/django/utils/functional.py", line 36, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/pi/.local/lib/python3.5/site-packages/django/urls/resolvers.py", line 529, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 673, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/home/pi/Projects/openvpn-monitor/openvpnmonitor/urls.py", line 24, in <module>
    url(r'^api/', include('openvpnmonitor.api.urls')),
  File "/home/pi/.local/lib/python3.5/site-packages/django/urls/conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "/usr/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 673, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/home/pi/Projects/openvpn-monitor/openvpnmonitor/api/urls.py", line 16, in <module>
    urlpatterns += router.urls
  File "/home/pi/.local/lib/python3.5/site-packages/rest_framework/routers.py", line 101, in urls
    self._urls = self.get_urls()
  File "/home/pi/.local/lib/python3.5/site-packages/rest_framework/routers.py", line 363, in get_urls
    urls = super(DefaultRouter, self).get_urls()
  File "/home/pi/.local/lib/python3.5/site-packages/rest_framework/routers.py", line 261, in get_urls
    routes = self.get_routes(viewset)
  File "/home/pi/.local/lib/python3.5/site-packages/rest_framework/routers.py", line 176, in get_routes
    extra_actions = viewset.get_extra_actions()
AttributeError: type object 'SessionViewSet' has no attribute 'get_extra_actions'

My views.py has the following code:

from django.shortcuts import render

from rest_framework import viewsets
from .models import Session
from .serializers import SessionSerializer

from rest_framework.views import APIView, Response


class SessionViewSet(APIView):
    queryset = Session.objects.all()
    serializer_class = SessionSerializer

    def get(self, request, format=None):
        return Response("test")

I really don't know why is working on my laptop but it is not working on my Raspberry Pi.

Has this happened to someone or anyone knows why is happening this?

Thank you so much!

Edit:

Here is my urls.py

from django.conf.urls import url
from rest_framework import routers
from openvpnmonitor.api.views import SessionViewSet

router = routers.DefaultRouter()
router.register(r'sessions', SessionViewSet)

urlpatterns = [
    url(r'sessions', SessionViewSet.as_view()),
    url(r'^docs/', schema_view),
]

urlpatterns += router.urls

Solution 1

You've called it a viewset, but that doesn't make it one; you inherit from APIView which is a standalone generic view, not a viewset.

A viewset needs to inherit from viewsets.ViewSet.

Solution 2

Before Django Rest Framework v3.8 you could register an APIView directly with a router. I did this extensively to gain a nice collated (and versioned) auto-documenting API for some very custom API endpoints. Given the choice again, I would probably write the whole thing a more standard way, but that isn't an option for everybody.

But after digging into the error, it turns out you can just patch over the problem by giving the router what it wants and adding a dummy get_extra_actions classmethod.

class MyAPIView(APIView):

    @classmethod
    def get_extra_actions(cls):
        return []

#...

I'm not saying this is good, but it works for now.
I've got my documentation back and I've managed to upgrade to DRFv3.8.

Solution 3

For:

djangorestframework==3.11.0
Django==2.2.9

You need to change class SessionViewSet(APIView): to:

from rest_framework import mixins, viewsets

class SessionViewSet(mixins.ListModelMixin,
                     viewsets.GenericViewSet):

To get it to work. The internals of DRF have changed a bit and the other solutions won't cut it any longer.

Solution 4

In views.py, your viewset have to inherit from viewset and use it in your viewset try code below:

class SessionViewSet(viewsets.ModelViewSet):
    queryset = Session.objects.all()
    serializer_class = SessionSerializer

    def get(self, request, format=None):
        return Response("test")

Solution 5

Beware of using the same names for your viewset class and your model class. This was the reason for my own error. See example of what i did

# inside member/views.py
from member.models import Member

# inheriting from model viewset but called Member
class Member(viewsets.ModelViewSet):
    queryset = Member.objects.all()
    ...

# inside urls.py
from member.views import Member

router = routers.DefaultRouter()
router.register(r'member', Member)

Now the mistake here is its importing the member model instead of the viewset but they are of the same names

View more solutions

Comments

[Daniel Roseman]

I don't understand what you mean. That tutorial creates both viewsets and a standalone APIView; you seem to be mixing up the two methods.

[alexca]

Yes, that tutorial creates both viewsets and a standalone APIView, I've created just a APIView to have a custom view and have just the GET endpoint instead of the CRUD, and that's working in my laptop, I mean, if I run the project on my laptop it works right, but I'm trying to run the same project on my raspberry pi and I'm getting that error. I've just tried to change the APIView to a ViewSet on the Raspberry Pi and it works, but I want to use an APIView to have an endpoint with just the GET endpoint.

[Daniel Roseman]

You need to show your urls.py; as you can see from the tutorial, viewsets and standalone views are referenced differently in the urls.

[alexca]

Thank you Daniel, I just edited my question and I've added my urls.py

[Daniel Roseman]

You're registering that view twice. You don't need a router for a standalone view. (Note, you really shouldn't call it a viewset in the first place if it is not one.)

[alexca]

Thank you Daniel!! I was reading a bit more about APIView once you said that I don't need a router for a standalone view and I modified my urls.py using format_suffix_patterns instead of routes and It works now! thank you!

[pass-by-ref]

The most important statement in the explanation is - You don't need a router for a standalone view. This statement solved all my problems. Thanks.

[Oleg Belousov]

Hi! I am using DRF 3.10.2 with Django 2.2.4. Adding this stub method results in the router ignoring this route :(

[MartinP]

typo, viewsets.ViewSet

[rmcsharry]

As of Apr 2020, this is the up-to-date answer. Thank you!

[Thusjanthan Kubendranathan]

If you look at the DRF viewsets.py, it does extend from APIView and ViewSetMixin, the latter implements the get_extra_actions and so if you extend from viewsets.ViewSet, that should be good.