Backend for authentication

backends.py

class FacebookBackend:
    
    def authenticate(self, token=None):
        
        facebook_session,created = models.FacebookSession.objects.get_or_create(access_token=token,)

        try:
            profile = facebook_session.query('me')
        except models.FacebookSessionError,e:
            raise e

        user = User.objects.create_user(...)


        facebook_session.user = user
        facebook_session.save()

        user.backend='punchtab.puncher.backends.FacebookBackend'

        return user
   
    def get_user(self, user_id):

        try:
            return User.objects.get(pk=user_id)
        except User.DoesNotExist:
            return None