Trailing slash is missing in a "catchall" pattern in flatpages URLconf example.

[Bryant Glisson]

We would like to append slashes to all URLs that do not have them, and we would also like to have a catchall flatpage expression, so our editors can enter whatever they like in that area of the CMS. The problem is that the flatpage validator adds the slash, but then only checks to see if a Flatpage exists for the resultant path (​https://github.com/django/django/blob/master/django/contrib/flatpages/views.py#L41), whereas the is_valid_path method (​https://github.com/django/django/blob/b9cf764be62e77b4777b3a75ec256f6209a57671/django/urls/base.py#L150) checks the urlconf, of which the catchall is a part, returns True, because the non-slash url fits the catchall. Hence, it does not redirect to the slashed version, making it impossible to reach and resulting in a 404.

Again, here is the flow:

1. Attempt to reach "/my-valid-page-without-a-slash"
2. is_valid_path returns True because "/my-valid-page-without-a-slash" fits the flatpage catchall and hence does not append a slash
3. The page is not found in Flatpage entries, resulting in 404

It seems to me that if APPEND_SLASH is set to True, then we should not be looking in the urlconf for the page without the slash, but should instead immediately append the slash, then check the urlconf, in which case the correct pattern would be found and flatpages would never be called.

[Mariusz Felisiak]

Thanks for this ticket, I think there is a regression introduced in df41b5a05d4e00e80e73afe629072e37873e767a in flatpages ​docs, i.e. a "catchall" pattern should contain a trailing slash when you use APPEND_SLASH:

urlpatterns += [
    path('<path:url>/', views.flatpage),
]

Can you check your app with this change?

[Ninad Kulkarni]

I would like to work on this ticket but could someone please guide me about how to solve this issue?

[Mariusz Felisiak]

Ninad, there is nothing to work on for a moment. Ticket is still not accepted, we're waiting for confirmation from the reporter that it's a documentation regression.

[Mariusz Felisiak]

meesterguyman, I understand that you're not using contrib.flatpages.forms.FlatpageForm because in such case trailing slash is required when APPEND_SLASH is True. I confirmed that when you allow for URLs without a trailing slash and want to use a “catchall” pattern then a trailing slash is required in:

path('<path:url>/', views.flatpage)

It's a regression in df41b5a05d4e00e80e73afe629072e37873e767a.

[Mariusz Felisiak]

Ninad, we need to add a trailing slash to ​flatpages URLconf example.

[Hasan Ramezani]

​PR

[GitHub <noreply@…>]

In a0916d7:

Fixed #31330 -- Updated flatpages URLconf example to work with APPEND_SLASH.

Regression in df41b5a05d4e00e80e73afe629072e37873e767a.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 6831049:

[3.0.x] Fixed #31330 -- Updated flatpages URLconf example to work with APPEND_SLASH.

Regression in df41b5a05d4e00e80e73afe629072e37873e767a.
Backport of a0916d7212aaae634f4388d47d8717abc2cd9036 from master

[Simon Barnett]

I think the addition of the slash causes a different problem.

Any valid page URL will match the catch all pattern, but the actual URL that is captured will not have the last slash in it. This will cause the flatpages view code to fail to find the page, add a slash to the URL and then return a permanent redirect to that URL with an extra slash on the end of it. So if the URL is '/someurl/', the user will be redirected to '/someurl//'.

I think the last slash needs to be inside the captured part of the URL, which can be done with re_path, like this:-

re_path('^(?P<url>.+/)$', views.flatpage)

[Mariusz Felisiak]

Simon, Thanks.

​PR

[Carlton Gibson <carlton.gibson@…>]

In 8f2a6c76:

Fixed #31330 -- Corrected catchall URL pattern in flatpages docs.

Use re_path() pattern with the regex used before original regression in
df41b5a05d4e00e80e73afe629072e37873e767a.
Regression in a0916d7212aaae634f4388d47d8717abc2cd9036.

[Carlton Gibson <carlton.gibson@…>]

In 3bb1e6c:

[3.0.x] Fixed #31330 -- Corrected catchall URL pattern in flatpages docs.

Use re_path() pattern with the regex used before original regression in
df41b5a05d4e00e80e73afe629072e37873e767a.
Regression in a0916d7212aaae634f4388d47d8717abc2cd9036.

Backport of 8f2a6c76d19e4010c4683b20ed7f1eb4b07c17eb from master