django-rest-framework returning 403 response on POST, PUT, DELETE despite AllowAny permissions

Django REST Framework returns status code 403 under a couple of relevant circumstances:

• When you don't have the required permission level (e.g. making an API request as an unauthenticated user when DEFAULT_PERMISSION_CLASSES is ('rest_framework.permissions.IsAuthenticated',).
• When you doing an unsafe request type (POST, PUT, PATCH or DELETE - a request that should have side effects), you are using rest_framework.authentication.SessionAuthentication and you've not included your CSRFToken in the requeset.
• When you are doing an unsafe request type and the CSRFToken you've included is no longer valid.

I'm going to make a few demo requests against a test API to give an example of each to help you diagnose which issue you are having and show how to resolve it. I'll be using the requests library.

The test API

I set up a very simple DRF API with a single model, Life, that contains a single field (answer, with a default value of 42). Everything from here on out is pretty straight forward; I set up a ModelSerializer - LifeSerializer, a ModelViewSet - LifeViewSet, and a DefaultRouter on the /life URL route. I've configured DRF to require user's be authenticated to use the API and to use SessionAuthentication.

Hitting the API

import json
import requests

response = requests.get('http://localhost:8000/life/1/')
# prints (403, '{"detail":"Authentication credentials were not provided."}')
print response.status_code, response.content

my_session_id = 'mph3eugf0gh5hyzc8glvrt79r2sd6xu6'
cookies = {}
cookies['sessionid'] = my_session_id
response = requests.get('http://localhost:8000/life/1/',
                        cookies=cookies)
# prints (200, '{"id":1,"answer":42}')
print response.status_code, response.content

data = json.dumps({'answer': 24})
headers = {'content-type': 'application/json'}
response = requests.put('http://localhost:8000/life/1/',
                        data=data, headers=headers,
                        cookies=cookies)
# prints (403, '{"detail":"CSRF Failed: CSRF cookie not set."}')
print response.status_code, response.content

# Let's grab a valid csrftoken
html_response = requests.get('http://localhost:8000/life/1/',
                             headers={'accept': 'text/html'},
                             cookies=cookies)
cookies['csrftoken'] = html_response.cookies['csrftoken']
response = requests.put('http://localhost:8000/life/1/',
                        data=data, headers=headers,
                        cookies=cookies)
# prints (403, '{"detail":"CSRF Failed: CSRF token missing or incorrect."}')
print response.status_code, response.content

headers['X-CSRFToken'] = cookies['csrftoken']
response = requests.put('http://localhost:8000/life/1/',
                        data=data, headers=headers,
                        cookies=cookies)
# prints (200, '{"id":1,"answer":24}')
print response.status_code, response.content

Just for anyone that might find the same problem. If you are using viewsets without routers like:

user_list = UserViewSet.as_view({'get': 'list'})
user_detail = UserViewSet.as_view({'get': 'retrieve'})

Django Rest framework will return 403 unless you define permission_classes at a class level:

class UserViewSet(viewsets.ModelViewSet):
    """
    A viewset for viewing and editing user instances.
    """
    permission_classes= YourPermisionClass

Hope it helps!

For completeness sake, there is one more circumstance under which DRF returns code 403: if you forget to add as_view() to the view declaration in your urls.py file. Just happened to me, and I spent hours until I found where the issue was, so maybe this addition can save some time for someone.