django.contrib.flatpages.urls does not have an app_name attribute

[William Morrell]

In 2.0, the include function in django.urls changed to drop the app_name argument, but an app_name attribute to the urls module is still required when setting a namespace on an include call. The urls.py in contrib.flatpages does not include an app_name attribute, so code like this will break:

urlpatterns = [
    # ...
    path('my-flat-pages/', include('django.contrib.flatpages.urls', namespace='my-custom-namespace')),
]

[Carlton Gibson]

You're right: there is no app_name but we can't just introduce one, since that would break existing usages.

If you want to namespace the URLs you can use the third case from ​the `include()` docs:

include((pattern_list, app_namespace), namespace=None)

Assuming you don't also need a instance namespace, you'd do something like:

from django.contrib.flatpages.urls import urlpatterns as flatpages_patterns

urlpatterns = [
    # ...
    path('my-flat-pages/', include((flatpages_patterns, 'my-custom-namespace',)),
]