Django and Middleware which uses request.user is always Anonymous

Came across this today while having the same problem.

TL;DR;

Skip below for code example

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Explanation

Thing is DRF have their own flow of things, right in the middle of the django request life-cycle.

So if the normal middleware flow is :

1. request_middleware (before starting to work on the request)
2. view_middleware (before calling the view)
3. template_middleware (before render)
4. response_middleware (before final response)

DRF code, overrides the default django view code, and executes their own code.

In the above link, you can see that they wrap the original request with their own methods, where one of those methods is DRF authentication.

So back to your question, this is the reason using request.user in a middleware is premature, as it only gets it’s value after view_middleware** executes.

The solution I went with, is having my middleware set a LazyObject.
This helps, because my code (the actual DRF ApiVIew) executes when the actual user is already set by DRF’s authentication.
This solution was proposed here together with a discussion.

Might have been better if DRF had a better way to extend their functionality, but as things are, this seems better than the provided solution (both performance and readability wise).

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Code Example

from django.utils.functional import SimpleLazyObject

def get_actual_value(request):
    if request.user is None:
        return None

    return request.user #here should have value, so any code using request.user will work


class MyCustomMiddleware(object):
    def process_request(self, request):
        request.custom_prop = SimpleLazyObject(lambda: get_actual_value(request))

Based on Daniel Dubovski’s very elegant solution above, here’s an example of middleware for Django 1.11:

from django.utils.functional import SimpleLazyObject
from organization.models import OrganizationMember
from django.core.exceptions import ObjectDoesNotExist


def get_active_member(request):
    try:
        active_member = OrganizationMember.objects.get(user=request.user)
    except (ObjectDoesNotExist, TypeError):
        active_member = None
    return active_member


class OrganizationMiddleware(object):
    def __init__(self, get_response):
        self.get_response = get_response


    def __call__(self, request):
        # Code to be executed for each request before
        # the view (and later middleware) are called.

        request.active_member = SimpleLazyObject(lambda: get_active_member(request))

        response = self.get_response(request)

        # Code to be executed for each request/response after
        # the view is called.
        return response

I know it’s not exactly answering the ‘can we access that from the middleware’ question, but I think it’s a more elegant solution VS doing the same work in the middleware VS what DRJ does in its base view class. At least for what I needed, it made more sense to add here.

Basically, I’m just overriding the method ‘perform_authentication()’ from DRF’s code, since I needed to add more things related to the current user in the request. The method just originally call ‘request.user’.

class MyGenericViewset(viewsets.GenericViewSet):

    def perform_authentication(self, request):
        request.user

        if request.user and request.user.is_authenticated():
            request.my_param1 = 'whatever'

After that in your own views, instead of settings APIView from DRF as a parent class, simply set that class as a parent.

Daniel Dubovski’s solution is probably the best in most cases.

The problem with the lazy object approach is if you need to rely on the side effects. In my case, I need something to happen for each request, no matter what.

If I’d use a special value like request.custom_prop, it has to be evaluated for each request for the side effects to happen. I noticed that other people are setting request.user, but it doesn’t work for me since some middleware or authentication class overwrites this property.

What if DRF supported its own middleware? Where could I plug it in? The easiest way in my case (I don’t need to access the request object, only the authenticated user) seems to be to hook into the authentication class itself:

from rest_framework.authentication import TokenAuthentication

class TokenAuthenticationWithSideffects(TokenAuthentication):

    def authenticate(self, request):
        user_auth_tuple = super().authenticate(request)

        if user_auth_tuple is None:
            return
        (user, token) = user_auth_tuple

        # Do stuff with the user here!

        return (user, token)

Then I could just replace this line in my settings:

REST_FRAMEWORK = {
    "DEFAULT_AUTHENTICATION_CLASSES": (
        #"rest_framework.authentication.TokenAuthentication",
        "my_project.authentication.TokenAuthenticationWithSideffects",
    ),
    # ...
}

I’m not promoting this solution, but maybe it will help someone else.

Pros:

• It to solves this specific problem
• There’s no double authentication
• Easy to maintain

Cons:

• Not tested in production
• Things happen in an unexpected place
• Side effects…

I wasn’t quite happy with the solutions out there. Here’s a solution that uses some DRF internals to make sure that the correct authentication is applied in the middleware, even if the view has specific permissions classes. It uses the middleware hook process_view which gives us access to the view we’re about to hit:

class CustomTenantMiddleware():
    def process_view(self, request, view_func, view_args, view_kwargs):
        # DRF saves the class of the view function as the .cls property
        view_class = view_func.cls
        try:
            # We need to instantiate the class
            view = view_class()
            # And give it an action_map. It's not relevant for us, but otherwise it errors.
            view.action_map = {}
            # Here's our fully formed and authenticated (or not, depending on credentials) request
            request = view.initialize_request(request)
        except (AttributeError, TypeError):
            # Can't initialize the request from this view. Fallback to using default permission classes
            request = APIView().initialize_request(request)

        # Here the request is fully formed, with the correct permissions depending on the view.

Note that this doesn’t avoid having to authenticate twice. DRF will still happily authenticate right afterwards.

I had the same issue and decided to change my design. Instead of using a Middleware I simply monkey-patch rest_framework.views.APIView.

In my case I needed to patch check_permissions but you can patch whatever fits your problem. Have a look at the the source code.

settings.py

INSTALLED_APPS = [
    ..
    'myapp',
]

myapp/patching.py

import sys

from rest_framework.views import APIView as OriginalAPIView


class PatchedAPIView(OriginalAPIView):
    def check_permissions(self, request):
        print(f"We should do something with user {request.user}"
        return OriginalAPIView.check_permissions(self, request)


# We replace the Django REST view with our patched one
sys.modules['rest_framework'].views.APIView = PatchedAPIView

myapp/__init__.py

from .patching import *

The accepted answer only takes TokenAuthentication in consideration – in my case, there are more authentication methods configured. I thus went with initializing the DRF’s Request directly which invokes DRF’s authentication machinery and loops through all configured authentication methods.

Unfortunately, it still introduces an additional load on the database since the Token object must be queried (the accepted answer has this problem as well). The trick with SimpleLazyObject in this answer is a much better solution, but it didn’t work for my use case because I need the user info in the middleware directly – I’m extending the metrics in django_prometheus and it processes the request before get_response is called.

from rest_framework.request import Request as RestFrameworkRequest
from rest_framework.views import APIView

class MyMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        drf_request: RestFrameworkRequest = APIView().initialize_request(request)
        user = drf_request.user
        ...
        return self.get_response(request)