Technical 404 could say which view was run, if any.

[Keryn Knight <django@…>]

Given a view:

def myview(request):
    raise Http404('test')

which is mounted at, say, /a/b/c/, where a and b may be url namespaces themselves (ie: urlconfs pulled together via include('x.y')) it is laborious to actually establish the callable that was executed, without using django-debug-toolbar; you have to manually traverse from the ROOT_URLCONF to wherever the urlpatterns which mount the myview are (or use something like django-extensions show_urls; etc etc)

Coming on board to an existing project could be thus made easier, if, when a 404 is thrown by a view (rather than the absence of a view) information was expressed about where to look to alter or fix that.

In DEBUG, when the TECHNICAL_404_TEMPLATE is used, it ought to be possible to attempt to resolve the request.path to a named callable in many circumstances by adding a new value to the technical_404_response's Context, using something like the tests debug-toolbar does, which I reproduce here (changed for brevity/structure) in case they change over time:

name = _("<no view>")
try:
    obj = resolve(request.path)
except Resolver404:  # not what debug-toolbar catches; don't know why.
    pass
else:
    if hasattr(obj, '__name__'):
        name = obj.__name__
    elif hasattr(obj, '__class__') and hasattr(obj.__class__, '__name__'):
        name = obj.__class__.__name__

    if hasattr(obj, '__module__'):
        module = obj.__module__
        name = '%s.%s' % (module, name)

[jooyous]

I made a pull request: ​https://github.com/django/django/pull/2822

[Tim Graham]

I left comments for improvement on PR. Please uncheck "Patch needs improvement" when you update it, thanks.

[jooyous]

I updated the patch, but I didn't add a test to make sure the view path is displayed instead of the view name. I tried adding one, but the view path was coming out automatically in the testing setup before I made this change.

[Tim Graham]

Looks good. I noted how you can update the test so that it will fail with the old version of the code and also suggested one more test so that all code paths are tested.

[jooyous]

The test meant to fail on the old version still didn't work for me, so I left it out.

[Tim Graham <timograham@…>]

In 29c1151a5577cccfdb18109ccb42330cde124d89:

Fixed #22756 -- Added view name to technical 404 template if Http404 is raised.

Thanks Keryn Knight for the suggestion.