Email and Username Authentication Backend

from django.contrib.auth.backends import ModelBackend
from django.contrib.auth.hashers import check_password
from django.contrib.auth import get_user_model

class LoginBackend(ModelBackend):

    def authenticate(self, username=None, password=None, **kwargs):
        user = super(LoginBackend, self).authenticate(username, password, **kwargs)
        if user:
            return user

        UserModel = get_user_model()
        try:
            user = UserModel.objects.get(email=username)
        except UserModel.DoesNotExist:
            return None

        if check_password(password, user.password):
            return user
        return None