Middleware for Django to authenticate a user with an OAuth token

authentication.py

from pprint import pprint
import re

from django.conf import settings
from django.contrib.auth.models import User, check_password
from django.contrib.auth import authenticate, login

from apps.api.authentication import verify_access_token, OAuthError

class OAuth2Middleware( object ):
    """Authentication Middleware for logging in with a token.
    Backend will get user.
    """
    def process_request(self, request):
        #if not hasattr(request, 'user'):
        #    raise ImproperlyConfigured()
        token = None
        if 'HTTP_AUTHORIZATION' not in request.META:
            if "oauth2_token" not in request.GET:
                return
            #print "authentication via get request params!"
            token = request.GET["oauth2_token"]
        else:
            #print "authenticating via authorization header!"
            auth_header = request.META['HTTP_AUTHORIZATION']
            auth_method, token = re.split(re.compile(r'\s+', re.U), auth_header, 1)

        if token is None:
            return

        full_token = None
        try:
            full_token = verify_access_token(token)
        except OAuthError, e:
            pass

        if full_token is None:
            return

        user = full_token.user
        # this is an ugly fix to make the login work
        # See the authenticate method at:
        # https://github.com/django/django/blob/master/django/contrib/auth/__init__.py
        user.backend = "%s.%s" % (self.__module__, self.__class__.__name__)
        #print "User:"
        #pprint(user)
        request.user = user
        login(request, user)

    def get_user(self, user_id):
        try:
            return User.objects.get(pk=user_id)
        except User.DoesNotExist:
            return None