What is the opposite of @login_required decorator for Django views?

As a previous poster mentioned, login not required is the default.

However, sometimes it's useful to block certain views from logged in users -- for instance, it makes no sense for a logged-in user to be able to use the site's signup page. In that case, you could do something like this, based off the existing login_required decorator

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

LOGGED_IN_HOME = settings.LOGGED_IN_HOME

def login_forbidden(function=None, redirect_field_name=None, redirect_to=LOGGED_IN_HOME):
    """
    Decorator for views that checks that the user is NOT logged in, redirecting
    to the homepage if necessary.
    """
    actual_decorator = user_passes_test(
        lambda u: not u.is_authenticated(),
        login_url=redirect_to,
        redirect_field_name=redirect_field_name
    )
    if function:
        return actual_decorator(function)
    return actual_decorator

A bit late, but another simple way to tackle this issue would be to rely on another decorator and add a lambda function:

from django.contrib.auth.decorators import user_passes_test

@user_passes_test(lambda u: u.is_anonymous)

Unfortunately, there's currently no built-in support for this in Django, leaving you at risk of exposing sensitive info when @login_required is accidentally forgotten.

Here's a solution from one of my projects:

middleware/security.py:

def public(function):
    """
    Decorator for public views that do not require authentication
    """
    orig_func = function
    while isinstance(orig_func, partial):  # if partial - use original function for authorization
        orig_func = orig_func.func
    orig_func.is_public_view = True
    
    return function

def is_public(function):
    try:                                    # cache is found
        return function.is_public_view
    except AttributeError:                  # cache is not found
        result = function.__module__.startswith('django.') and not function.__module__.startswith('django.views.generic') # Avoid modifying admin and other built-in views
        
        try:                                # try to recreate cache
            function.is_public_view = result
        except AttributeError:
            pass
        
        return result


class NonpublicMiddleware(object):

    def process_view_check_logged(self, request, view_func, view_args, view_kwargs):
        return
    
    def process_view(self, request, view_func, view_args, view_kwargs):
        while isinstance(view_func, partial):  # if partial - use original function for authorization
            view_func = view_func.func

        request.public = is_public(view_func)
        if not is_public(view_func):
            if request.user.is_authenticated():     # only extended checks are needed
                return self.process_view_check_logged(request, view_func, view_args, view_kwargs)

            return self.redirect_to_login(request.get_full_path())  # => login page

    def redirect_to_login(self, original_target, login_url=settings.LOGIN_URL):
        return HttpResponseRedirect("%s?%s=%s" % (login_url, REDIRECT_FIELD_NAME, urlquote(original_target)))

settings.py:

MIDDLEWARE_CLASSES = (
    #...
    'middleware.security.NonpublicProfilefullMiddleware',
    #...
)

and, finally, view code:

from <projname>.middleware import publi

@public
def some_view(request):
    #...
    
# Login required is added automatically
def some_private_view(request):
    #...

Also, you may want to look at "Automatically decorating all views of a django project" blog post