Django authentication override not working

Question

I created a file "authentication.py" at the same level as the "settings.py" file in my django project. The content of this file is:

from django.contrib.auth.models import User

class SettingsBackend(object):

    def authenticate(self, request, username=None, password=None):
        user_name = 'user_name'
        user_password = 'user_pass'
        login_valid = (user_name == username)
        pwd_valid = (password == user_password)
        if login_valid and pwd_valid:
            try:
                user = User.objects.get(username=username)
            except User.DoesNotExist:
                user = User(username=username)
                user.is_staff = True
                user.is_superuser = True
                user.save()
            return user
        return None

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

Then I added the following line in the "settings.py" file:

AUTHENTICATION_BACKENDS = ('myProject.authentication.SettingsBackend',)

However, the login doesn't work. It was working before these 2 modification when the user's credentials where stored in the database. I don't know how I can debug this. Any idea ?

Here are some pieces of my settings file:

INSTALLED_APPS = [
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.humanize',
    'default',
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': ["templates/"],
        'APP_DIRS': True,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
        },
    },
]

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}




# Password validation
# https://docs.djangoproject.com/en/1.10/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]

LOGIN_REDIRECT_URL = '/'
LOGIN_URL = '/login'
LOGOUT_URL = '/logout'
ADMIN_ENABLED = False

EDIT: I deleted the "db.sqlite3" file at the root of my folder, then ran the django shell and did:

from django.contrib.sessions.models import Session
Session.objects.all().delete()

Then I get this:

from django.contrib.auth.models import User
user = User.objects.get(username='user_name')
>> DoesNotExist: User matching query does not exist. 

Answer 1

You might try to run:

Session.objects.all().delete().

Before testing new auth backend. From the Django docs:

Once a user has authenticated, Django stores which backend was used to authenticate the user in the user’s session, and re-uses the same backend for the duration of that session whenever access to the currently authenticated user is needed. This effectively means that authentication sources are cached on a per-session basis, so if you change AUTHENTICATION_BACKENDS, you’ll need to clear out session data if you need to force users to re-authenticate using different methods. A simple way to do that is simply to execute Session.objects.all().delete().