[Python] Google OAuth2 Signup in Django: 'Bad Request' Error on First Signup Attempt

I'm working on integrating Google OAuth2 login/signup with Django, but I'm encountering an issue during the first signup attempt.

The Flow:

• 
  New User Registration using Google.
  
  
• 
  The user clicks on the "Login with Google" button.
  
  
• 
  The user is redirected to the Google OAuth2 consent screen and logs in.
  
  
• 
  After successful Signup, Google redirects back to my app with a Bad Request - "POST /api/v1/auth/google/ HTTP/1.1" 400 Bad Request : this only happens first time the user tries to sign up, It returns a "Bad Request" error. The issue only occurs during the first signup, even though the user data is added to the database.
  
  
• 
  If I try to login back with the same account using google now then i will be able to Login Successfully.
  

Relevant Code :

backend/api/urls.py :

path('auth/google/', GoogleLogin.as_view(), name='google_login')

backend/api/views.py :

from django.conf import settings
from django.http import HttpResponseRedirect

from allauth.socialaccount.providers.google.views import GoogleOAuth2Adapter
from allauth.socialaccount.providers.oauth2.client import OAuth2Client

from dj_rest_auth.registration.views import SocialLoginView

class GoogleLogin(SocialLoginView):
adapter_class = GoogleOAuth2Adapter
client_class = OAuth2Client
callback_uri = settings.REDIRECT_URI

def get(self, request):
return HttpResponseRedirect(redirect_to=settings.GOOGLE_AUTH_URL)



backend/api/adapter.py:

from allauth.socialaccount.adapter import DefaultSocialAccountAdapter

from api.models import User

class CustomSocialAdapter(DefaultSocialAccountAdapter):
def pre_social_login(self, request, sociallogin):
# Ignore existing social accounts, just do this stuff for new ones

if sociallogin.is_existing:
return

# some social logins don't have an email address, e.g. facebook accounts
# with mobile numbers only, but allauth takes care of this case so just
# ignore it

if 'email' not in sociallogin.account.extra_data:
return

# check if given email address already exists.
# Note: __iexact is used to ignore cases

try:
email = sociallogin.account.extra_data['email'].lower()
existing_user = User.objects.get(email__iexact=email)

# if it does not, let allauth take care of this new social account
except User.DoesNotExist:
return

# if it does, connect this new social login to the existing user
sociallogin.connect(request, existing_user)



Any help would be greatly appreciated!

Continue reading...