Add logging for {% include %} exceptions when template.debug = False

[Nick Johnson]

Exceptions raised from ModelAdmin fields during the rendering of the admin detail view for a model are silently caught and there's no simple way to log them without putting the template renderer in debug mode.

As a fix I'd like the ability to log these exceptions via the normal logging facilities, something akin to ​this change:

The problematic exception catching line is ​here

​example with reproduction steps

[Tim Graham]

Updated title to reflect that the issue is really about the template system and the {% include %} template tag, not the admin. As the docs note:

When debug mode is turned on, an exception like TemplateDoesNotExist or TemplateSyntaxError will be raised; otherwise {% include %} silences any exception that happens while rendering the included template and returns an empty string.

[Nick Johnson]

if you want these logged via the django.template logger I can put a patch together with a fix and a regression test for review

[Tim Graham]

I didn't have an alternate implementation in mind.

[Nick Johnson]

After some further digging it appears the django.template logger added in the commit I originally referenced will capture exceptions bubbled through this function, however it will also catch things like missing variables in templates and expected fallthrough behavior. All of this is at a level of DEBUG which seems appropriate.

In order to be able to log only unexpected exceptions, I'm proposing adding WARNING level logging to any uncaught exceptions during import templatetag rendering. See attached patch for changes and regression test.

[Nick Johnson]

fot ease of review I've created a PR here: ​https://github.com/django/django/pull/5285

[Simon Charette]

Left some comment on the PR.

[Simon Charette]

Given a docs review.

[Tim Graham]

Left a few comments for improvement.

[Nick Johnson]

should be all cleaned up

[Nick Johnson]

Should be all cleaned up again. docs and isort are broken on CI right now, but they're broken for all PRs and are not caused by my change.

[Tim Graham <timograham@…>]

In 392f6484:

Fixed #25373 -- Added warning logging for exceptions during {% include %} tag rendering.

[Tim Graham <timograham@…>]

In b1f60460:

Refs #25373 -- Doc'd logging of exceptions during {% include %} rendering.