django-auth-ldap email or username authentication

backends.py

from django_auth_ldap.backend import LDAPBackend, _LDAPUser


class LDAPUsernameBackend(LDAPBackend):
    settings_prefix = "AUTH_LDAP_U_"


class LDAPEmailBackend(LDAPBackend):
    settings_prefix = "AUTH_LDAP_E_"

    def get_or_create_user(self, email, ldap_user):
        """
        Use the Posixuser uid field as username instead of form value (email).

        This must return a (User, created) 2-tuple for the given LDAP user.
        username is the Django-friendly username of the user. ldap_user.dn is
        the user's DN and ldap_user.attrs contains all of their LDAP attributes.
        """
        model = self.get_user_model()
        username_field = getattr(model, 'USERNAME_FIELD', 'username')

        kwargs = {
            username_field + '__iexact': ldap_user.attrs['uid'][0],
            'defaults': {
                username_field: ldap_user.attrs['uid'][0].lower(),
                'email': email
            }
        }

        return model.objects.get_or_create(**kwargs)

settings.py

# snipped from settings.py

AUTHENTICATION_BACKENDS = (
    'app.backends.LDAPEmailBackend',
    'app.backends.LDAPUsernameBackend',
    'django.contrib.auth.backends.ModelBackend',
)

# LDAP username auth
AUTH_LDAP_U_USER_SEARCH = LDAPSearch("ou=people,dc=example,dc=com", ldap.SCOPE_ONELEVEL, "(uid=%(user)s)")
# User attribute mappings
AUTH_LDAP_U_USER_ATTR_MAP = {
    "first_name": "givenName",
    "last_name": "sn",
    "email": "mail",
}
# Allways update the django user object on authentication.
AUTH_LDAP_U_ALWAYS_UPDATE_USER = True

# LDAP email auth
AUTH_LDAP_E_USER_SEARCH = LDAPSearch("ou=people,dc=example,dc=com", ldap.SCOPE_ONELEVEL, "(mail=%(user)s)")
AUTH_LDAP_E_USER_ATTR_MAP = AUTH_LDAP_U_USER_ATTR_MAP
AUTH_LDAP_E_ALWAYS_UPDATE_USER = AUTH_LDAP_U_ALWAYS_UPDATE_USER