Ticket #5925: 5925.reverse_lazy.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/releases/1.4.txt

@@ -37 +37 @@
 features you need in admin pages without having to lose HTML validity or
 override the provided templates to change the doctype.
 
+``reverse_lazy``
+~~~~~~~~~~~~~~~~
+
+A lazily evaluated version of ``django.core.urlresolvers.reverse()`` was added
+to allow using URL reversals before the project's URLConf gets loaded.
+
 .. _backwards-incompatible-changes-1.4:
 
 Backwards incompatible changes in 1.4

docs/topics/http/urls.txt

@@ -827 +827 @@
     ``urllib.quote``) to the ouput of :meth:`~django.core.urlresolvers.reverse`
     may produce undesirable results.
 
+reverse_lazy()
+--------------
+
+.. versionadded:: 1.4
+
+A lazily evaluated version of `reverse()`_.
+
+It is useful for when you need to use a URL reversal before your project's
+URLConf is loaded. Some common cases where this method is necessary are::
+
+* providing a reversed URL as the ``url`` attribute of a generic class-based
+  view.
+
+* providing a reversed URL to a decorator (such as the ``login_url`` argument
+  for the ``django.contrib.auth.decorators.permission_required`` decorator).
+
+* providing a reversed URL as a default value for a parameter in a function's
+  signature.
+
 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 import RedirectView
+
+from views import empty_view
+
+
+class LazyRedictView(RedirectView):
+    url = reverse_lazy('named-lazy-url-redirected-to')
+
+urlpatterns = patterns('',
+    url(r'^redirected_to/$', empty_view, name='named-lazy-url-redirected-to'),
+    url(r'^redirect/$', LazyRedictView.as_view()),
+)

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, "/redirected_to/", status_code=301)
+
 class ReverseShortcutTests(TestCase):
     urls = 'regressiontests.urlpatterns_reverse.urls'