我正在尝试创建一个auth后端，以允许我的用户使用他们的电子邮件地址或他们在Django 1.6中使用自定义用户模型的用户名登录。当我使用用户名登录时，后端工作正常，但由于某种原因，没有电子邮件。有什么我忘记要做的事吗？

from django.conf import settings
from django.contrib.auth.models import User

class EmailOrUsernameModelBackend(object):
    """
    This is a ModelBacked that allows authentication with either a username or an email address.

    """
    def authenticate(self, username=None, password=None):
        if '@' in username:
            kwargs = {'email': username}
        else:
            kwargs = {'username': username}
        try:
            user = User.objects.get(**kwargs)
            if user.check_password(password):
                return user
        except User.DoesNotExist:
            return None

    def get_user(self, username):
        try:
            return User.objects.get(pk=username)
        except User.DoesNotExist:
            return None

编辑：按照建议，我已从ModelBackend继承并将其安装在我的设置中。在我的设置中，我有这个AUTHENTICATION_BACKENDS =（'users.backends'，'django.contrib.auth.backends.ModelBackend'，）并且我将后端更改为这个：

from django.conf import settings
from django.contrib.auth.models import User
from django.contrib.auth.backends import ModelBackend
class EmailOrUsernameModelBackend(ModelBackend):
    """
    This is a ModelBacked that allows authentication with either a username or an email address.

    """
    def authenticate(self, username=None, password=None):
        if '@' in username:
            kwargs = {'email': username}
        else:
            kwargs = {'username': username}
        try:
            user = User.objects.get(**kwargs)
            if user.check_password(password):
                return user
        except User.DoesNotExist:
            return None

    def get_user(self, username):
        try:
            return User.objects.get(pk=username)
        except User.DoesNotExist:
            return None

现在我得到一个Module "users" does not define a "backends" attribute/class错误。