backends.py

# original by micah carrick

from django.contrib.auth.models import User, check_password

class EmailAuthBackend(object):
    """
    Email Authentication Backend
    
    Allows a user to sign in using an email/password pair rather than
    a username/password pair.
    """
    
    def authenticate(self, email=None, password=None):
        """ Authenticate a user based on email address """
        try:
            user = User.objects.get(email=email)
            if user.check_password(password):
                return user
            else:
                return None
        except User.DoesNotExist:
            return None

    def get_user(self, user_id):
        """ Get a User object from the user_id. """
        try:
            return User.objects.get(pk=user_id)
        except User.DoesNotExist:
            return None