Django Email as Username Authentication Backend

backends.py

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

class LoginUsingEmailAsUsernameBackend(object):
  """
  Custom Authentication backend that supports using an e-mail address
  to login instead of a username.

  See: http://blog.cingusoft.org/custom-django-authentication-backend
  """
  supports_object_permissions = False
  supports_anonymous_user = False
  supports_inactive_user = False

  def authenticate(self, username=None, password=None):
    try:
      # Check if the user exists in Django's database
      user = User.objects.get(email=username)
    except User.DoesNotExist:
      return None

    # Check password of the user we found
    if check_password(password, user.password):
      return user
    return None

  # Required for the backend to work properly - unchanged in most scenarios
  def get_user(self, user_id):
    try:
      return User.objects.get(pk=user_id)
    except User.DoesNotExist:
      return None

settings.py

# ...

AUTHENTICATION_BACKENDS = (
  'project.backends.LoginUsingEmailAsUsernameBackend',
  'django.contrib.auth.backends.ModelBackend',
)

# ...