Best way to make Django's login_required the default

I'm working on a large Django app, the vast majority of which requires a login to access. This means that all throughout our app we've sprinkled:

@login_required
def view(...):

That's fine, and it works great as long as we remember to add it everywhere! Sadly sometimes we forget, and the failure often isn't terribly evident. If the only link to a view is on a @login_required page then you're not likely to notice that you can actually reach that view without logging in. But the bad guys might notice, which is a problem.

My idea was to reverse the system. Instead of having to type @login_required everywhere, instead I'd have something like:

@public
def public_view(...):

Just for the public stuff. I tried to implement this with some middleware and I couldn't seem to get it to work. Everything I tried interacted badly with other middleware we're using, I think. Next up I tried writing something to traverse the URL patterns to check that everything that's not @public was marked @login_required - at least then we'd get a quick error if we forgot something. But then I couldn't figure out how to tell if @login_required had been applied to a view...

So, what's the right way to do this? Thanks for the help!

Middleware may be your best bet. I've used this piece of code in the past, modified from a snippet found elsewhere:

import re

from django.conf import settings
from django.contrib.auth.decorators import login_required


class RequireLoginMiddleware(object):
    """
    Middleware component that wraps the login_required decorator around
    matching URL patterns. To use, add the class to MIDDLEWARE_CLASSES and
    define LOGIN_REQUIRED_URLS and LOGIN_REQUIRED_URLS_EXCEPTIONS in your
    settings.py. For example:
    ------
    LOGIN_REQUIRED_URLS = (
        r'/topsecret/(.*)$',
    )
    LOGIN_REQUIRED_URLS_EXCEPTIONS = (
        r'/topsecret/login(.*)$',
        r'/topsecret/logout(.*)$',
    )
    ------
    LOGIN_REQUIRED_URLS is where you define URL patterns; each pattern must
    be a valid regex.

    LOGIN_REQUIRED_URLS_EXCEPTIONS is, conversely, where you explicitly
    define any exceptions (like login and logout URLs).
    """
    def __init__(self):
        self.required = tuple(re.compile(url) for url in settings.LOGIN_REQUIRED_URLS)
        self.exceptions = tuple(re.compile(url) for url in settings.LOGIN_REQUIRED_URLS_EXCEPTIONS)

    def process_view(self, request, view_func, view_args, view_kwargs):
        # No need to process URLs if user already logged in
        if request.user.is_authenticated():
            return None

        # An exception match should immediately return None
        for url in self.exceptions:
            if url.match(request.path):
                return None

        # Requests matching a restricted URL pattern are returned
        # wrapped with the login_required decorator
        for url in self.required:
            if url.match(request.path):
                return login_required(view_func)(request, *view_args, **view_kwargs)

        # Explicitly return None for all non-matching requests
        return None

Then in settings.py, list the base URLs you want to protect:

LOGIN_REQUIRED_URLS = (
    r'/private_stuff/(.*)$',
    r'/login_required/(.*)$',
)

As long as your site follows URL conventions for the pages requiring authentication, this model will work. If this isn't a one-to-one fit, you may choose to modify the middleware to suit your circumstances more closely.

What I like about this approach - besides removing the necessity of littering the codebase with @login_required decorators - is that if the authentication scheme changes, you have one place to go to make global changes.

There is an alternative to putting a decorator on each view function. You can also put the login_required() decorator in the urls.py file. While this is still a manual task, at least you have it all in one place, which makes it easier to audit.

e.g.,

    from my_views import home_view

    urlpatterns = patterns('',
        # "Home":
        (r'^$', login_required(home_view), dict(template_name='my_site/home.html', items_per_page=20)),
    )

Note that view functions are named and imported directly, not as strings.

Also note that this works with any callable view object, including classes.

In Django 2.1, we can decorate all methods in a class with:

from django.contrib.auth.decorators import login_required
from django.utils.decorators import method_decorator
from django.views.generic import TemplateView

@method_decorator(login_required, name='dispatch')
class ProtectedView(TemplateView):
    template_name = 'secret.html'

UPDATE: I have also found the following to work:

from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic import TemplateView

class ProtectedView(LoginRequiredMixin, TemplateView):
    template_name = 'secret.html'

and set LOGIN_URL = '/accounts/login/' in your settings.py

Here is a middleware solution for django 1.10+

The middlewares in have to be written in a new way in django 1.10+.

Code

import re

from django.conf import settings
from django.contrib.auth.decorators import login_required


class RequireLoginMiddleware(object):

    def __init__(self, get_response):
         # One-time configuration and initialization.
        self.get_response = get_response

        self.required = tuple(re.compile(url)
                              for url in settings.LOGIN_REQUIRED_URLS)
        self.exceptions = tuple(re.compile(url)
                                for url in settings.LOGIN_REQUIRED_URLS_EXCEPTIONS)

    def __call__(self, request):

        response = self.get_response(request)
        return response

    def process_view(self, request, view_func, view_args, view_kwargs):

        # No need to process URLs if user already logged in
        if request.user.is_authenticated:
            return None

        # An exception match should immediately return None
        for url in self.exceptions:
            if url.match(request.path):
                return None

        # Requests matching a restricted URL pattern are returned
        # wrapped with the login_required decorator
        for url in self.required:
            if url.match(request.path):
                return login_required(view_func)(request, *view_args, **view_kwargs)

        # Explicitly return None for all non-matching requests
        return None

Installation

1. Copy the code into your project folder, and save as middleware.py

2. Add to MIDDLEWARE

   MIDDLEWARE = [ ... '.middleware.RequireLoginMiddleware', # Require login ]

3. Add to your settings.py:

LOGIN_REQUIRED_URLS = (
    r'(.*)',
)
LOGIN_REQUIRED_URLS_EXCEPTIONS = (
    r'/admin(.*)$',
)
LOGIN_URL = '/admin'

Sources:

1. This answer by Daniel Naab

2. Django Middleware tutorial by Max Goodridge

3. Django Middleware Docs