Case-insensitive ModelBackend for Django

backends.py

# -*- coding: utf-8 -*-
"""
Case-Insensitive ModelBackend
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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"""

from django.contrib.auth.backends import ModelBackend as ModelBackend_
from django.contrib.auth import get_user_model

User = get_user_model()


class ModelBackend(ModelBackend_):
    """
    A bunch of idiots working on `django.contrib.auth` decided it would be a good idea to make
    usernames **case-sensitive**. This works around that.

    There is an open issue `on the topic`_, I added the following comment (copied here just in case
    it gets removed or the issue deleted):

        Whose idea was it to make usernames case-sensitive in the first place? I suppose nothing can
        be done at this point, but y'all probably should have thought about it a bit more before
        committing yourselves to it for so long. *It was a stupid decision.*

        Think about a user logging into a Django-powered site, do you think she gives a shit about
        which letters she capitalized when she filled out the registration form? I doubt it. Why
        even make her remember? Capitalization isn't that important!

    .. _on the topic: https://code.djangoproject.com/ticket/2273
    """
    def authenticate(self, **kwargs):
        try:
            key = '{0}__iexact'.format(User.USERNAME_FIELD)
            user = User.objects.get(**{key: kwargs.get(User.USERNAME_FIELD, kwargs.get('username'))})
            if user.check_password(kwargs['password']):
                return user
            else:
                return None
        except User.DoesNotExist:
            return None