[Fixed]-AuthAlreadyAssociated Exception in Django Social Auth

My approach to this problem was a little different, instead of tackling this in the pipeline, I made sure that a user was never passed into the pipeline in the first place. This way, even if the social_auth.user does not match the logged in user, the social_auth.user will be logged in on top of the currently logged in user.

I think it’s as easy as overriding the complete action.

urls.py

path('complete/<str:backend>/', 'account.views.complete', name='complete'),

account/views.py

from django.contrib.auth import REDIRECT_FIELD_NAME
from django.views.decorators.cache import never_cache
from django.views.decorators.csrf import csrf_exempt
from social_core.actions import do_complete
from social_django.utils import psa
from social_django.views import _do_login

@never_cache
@csrf_exempt
@psa('social:complete')
def complete(request, backend, *args, **kwargs):
    """Override this method so we can force user to be logged out."""
    return do_complete(request.backend, _do_login, user=None,
                       redirect_name=REDIRECT_FIELD_NAME, request=request,
                       *args, **kwargs)

Solution for people wondering how to override social_user pipeline under python-social-auth version 3+

In your settings.py:

SOCIAL_AUTH_PIPELINE = (
    'social_core.pipeline.social_auth.social_details',
    'social_core.pipeline.social_auth.social_uid',
    'social_core.pipeline.social_auth.auth_allowed',
    # Path to your overrided method
    # You can set any other valid path.
    'myproject.apps.python-social-auth-overrided.pipeline.social_auth.social_user',
    'social_core.pipeline.user.get_username',
    'social_core.pipeline.user.create_user',
    'social_core.pipeline.social_auth.associate_user',
    'social_core.pipeline.social_auth.load_extra_data',
    'social_core.pipeline.user.user_details',
)

In your overrided social_user:

from django.contrib.auth import logout

def social_user(backend, uid, user=None, *args, **kwargs):
    provider = backend.name
    social = backend.strategy.storage.user.get_social_auth(provider, uid)
    if social:
        if user and social.user != user:
            logout(backend.strategy.request)
        elif not user:
            user = social.user
    return {'social': social,
            'user': user,
            'is_new': user is None,
            'new_association': False}

You can delete commented lines if you want.

I got the same problem. I solved it by inserting below code in settings

AUTHENTICATION_BACKENDS = (
    '...',
    'social_core.backends.facebook.FacebookOAuth2',
    '...',
)
SOCIAL_AUTH_PIPELINE = (
    '...',
    'social_core.pipeline.user.user_details',
    '...',
)

What I have done is:

1. Define a class that inherits from SocialAuthExceptionMiddleware

2. Implement the method process_exception,

3. Add the implemented class to MIDDLEWARE list on settings.py.

In middleware.py, which should be in your apps’s directory, i.e., same directory of your views.py file associated with your app, define the following class:

from django.shortcuts import redirect
from django.urls import reverse

from social_core.exceptions import AuthAlreadyAssociated

class FacebookAuthAlreadyAssociatedMiddleware(SocialAuthExceptionMiddleware):
    """Redirect users to desired-url when AuthAlreadyAssociated exception occurs."""
    def process_exception(self, request, exception):
        if isinstance(exception, AuthAlreadyAssociated):
            if request.backend.name == "facebook":
                message = "This facebook account is already in use."
                if message in str(exception):
                    # Add logic if required

                    # User is redirected to any url you want
                    # in this case to "app_name:url_name"
                    return redirect(reverse("app_name:url_name"))

In settings.py, add the implemented class to the MIDDLEWARE list:

MIDDLEWARE = [
    # Some Django middlewares
    "django.middleware.security.SecurityMiddleware",
    "django.contrib.sessions.middleware.SessionMiddleware",
    "django.middleware.locale.LocaleMiddleware",
    "django.middleware.common.CommonMiddleware",
    "django.contrib.auth.middleware.AuthenticationMiddleware",
    "django.contrib.messages.middleware.MessageMiddleware",
    "django.middleware.clickjacking.XFrameOptionsMiddleware",
    "social_django.middleware.SocialAuthExceptionMiddleware",

    # the middleware you just implemented
    "app_name.middleware.FacebookAuthAlreadyAssociatedMiddleware",
]

This solved my problem, and I was able to handle the flow of control when the AuthAlreadyAssociated exception was raised.