Ticket #5925: 5925.2.diff

django/core/urlresolvers.py

@@ -15 +15 @@
 from django.core.exceptions import ImproperlyConfigured, ViewDoesNotExist
 from django.utils.datastructures import MultiValueDict
 from django.utils.encoding import iri_to_uri, force_unicode, smart_str
-from django.utils.functional import memoize
+from django.utils.functional import memoize, lazy
 from django.utils.importlib import import_module
 from django.utils.regex_helper import normalize
 
@@ -390 +390 @@
     return iri_to_uri(u'%s%s' % (prefix, resolver.reverse(view,
             *args, **kwargs)))
 
+reverse_lazy = lazy(reverse, str)
+
 def clear_url_caches():
     global _resolver_cache
     global _callable_cache

docs/topics/http/urls.txt

@@ -815 +815 @@
     be imported correctly. Do not include lines that reference views you
     haven't written yet, because those views will not be importable.
 
+reverse_lazy()
+--------------
+
+.. versionadded:: 1.3
+
+A lazily evaluated version of `reverse()`_.
+
+It is useful for when you need to use a URL reversal before Django's URL names
+map is loaded. Some common cases where this method is necessary are:
+
+* in your URL configuration (such as the ``url`` argument for the
+  ``django.views.generic.simple.redirect_to`` generic view).
+
+* providing a reversed URL to a decorator (such as the ``login_url`` argument
+  for the ``django.contrib.auth.decorators.permission_required`` decorator).
+
 resolve()
 ---------
 

new file tests/regressiontests/urlpatterns_reverse/reverse_lazy_urls.py

@@ +1 @@
+from django.conf.urls.defaults import *
+from django.core.urlresolvers import reverse_lazy
+from django.views.generic.simple import redirect_to
+
+from views import empty_view
+
+urlpatterns = patterns('',
+    url(r'^$', empty_view, name='named-lazy-url-1'),
+    url(r'^redirect/$', redirect_to, dict(url=reverse_lazy('named-lazy-url-1'))),
+)

tests/regressiontests/urlpatterns_reverse/tests.py

@@ -218 +218 @@
                         else:
                             self.assertEqual(t.name, e['name'], 'Wrong URL name.  Expected "%s", got "%s".' % (e['name'], t.name))
 
+class ReverseLazyTest(TestCase):
+    urls = 'regressiontests.urlpatterns_reverse.reverse_lazy_urls'
+
+    def test_redirect_with_lazy_reverse(self):
+        response = self.client.get('/redirect/')
+        self.assertRedirects(response, "/", status_code=301)
+
 class ReverseShortcutTests(TestCase):
     urls = 'regressiontests.urlpatterns_reverse.urls'