urlresolvers.reverse returns '/$' when including namespaced '^$' pattern at root '^$'

[David Bennett]

In project urls.py:

incpatterns = patterns('',
    url(r'^$', myapp.views.index, name='index'),
)
urlpatterns = patterns('',
    (r'^$', include(incpatterns, namespace='myapp')),
)

>>> reverse('myapp:index')
'/$'

It correctly returns '/' if the included pattern isn't namespaced.

[Alex Gaynor]

Your resolver is broken, you can't include at something ending with a $.

[David Bennett]

I figured as much, but was confused by it working when a namespace wasn't specified.

Thanks!

[Chris Beaven]

No, there's definitely something fishy going on.

[Chris Beaven]

Normal:

incpatterns = patterns('',
    url(r'^$', 'views.front', name='index'),
)
urlpatterns = patterns('views',
    (r'test?/', include(incpatterns)),
)

>>> reverse('index')
'/tes/

Namespaced:

incpatterns = patterns('',
    url(r'^$', 'views.front', name='index'),
)
urlpatterns = patterns('views',
    (r'test?/', include(incpatterns, namespace='myapp')),
)

>>> reverse('myapp:index')
'/test?/

[v1v3kn]

@SmileyChris

This is not really a bug, this is due to the way the '?' quantifier works.

'?' matches the character preceding it zero or one time(s).

Eg: the regex pattern 'cows' matches both 'cow' and 'cows'.

And as Alex said earlier, you can't include anything after a '$'.

[Chris Beaven]

Perhaps you misread my example code. I didn't include anything after a '$'.

And I understand how quantifiers work. The issue here is that a namespaced app isn't processing the regular expression question mark as expected.

I haven't actually retested my code, but your reasoning for closing doesn't show that you did either so I'll reopen.

[David Bennett]

Regex for namespaced RegexURLResolver wasn't getting processed.

I believe I have found a solution. Please see patch.

[David Bennett]

Hadn't run tests on my patch. They break.

Will do some more digging and add a regression test for this.

[David Bennett]

Added a simple regression test. Will see if I can figure out how to resolve.

[David Bennett]

Fix parsing url regex patterns when including namespaced urls.

[David Bennett]

New patch passes tests.

What patch does is copy namespaced resolver into non-namespace resolver, then wraps with root resolver so that everything works.

[Carl Meyer]

I believe this is a duplicate of #11559.