auth_decorators.py

from django.utils.http import urlquote
from functools import wraps
from django.utils.decorators import available_attrs
from django.contrib.auth import REDIRECT_FIELD_NAME
from common.shortcuts import render_json
from django.http import HttpResponseRedirect

def user_passes_test(test_func, login_url=None, redirect_field_name=REDIRECT_FIELD_NAME):
    """
    MODIFIED from django/contrib/auth/decorators.py - now returns our custom JSON-failure
    message for AJAX requests.
    
    Decorator for views that checks that the user passes the given test,
    redirecting to the log-in page if necessary. The test should be a callable
    that takes the user object and returns True if the user passes.
    """
    if not login_url:
        from django.conf import settings
        login_url = settings.LOGIN_URL

    def decorator(view_func):
        def _wrapped_view(request, *args, **kwargs):
            if test_func(request.user):
                return view_func(request, *args, **kwargs)
            if request.is_ajax():
                return render_json({
                    'fatal-error': True,
                    'description': 'You are not logged in!'
                })
            path = urlquote(request.get_full_path())
            tup = login_url, redirect_field_name, path
            return HttpResponseRedirect('%s?%s=%s' % tup)
        return wraps(view_func, assigned=available_attrs(view_func))(_wrapped_view)
    return decorator

def permission_required(perm, login_url=None):
    """
    Decorator for views that checks whether a user has a particular permission
    enabled, redirecting to the log-in page if necessary.
    """
    return user_passes_test(lambda u: u.has_perm(perm), login_url=login_url)