Have SingleObjectMixin.get_object handle ValidationError/ValueError

[Alex Tomkins]

Vaguely related ticket from 10 years ago(!) - #22303

Currently get_object in the Django admin handles ValidationError/ValueError ​https://github.com/django/django/blob/6e520d953773d25a3d3484db67feed446aca0bc1/django/contrib/admin/options.py#L896. This is needed as the URL patterns for the Django admin are fairly relaxed to handle objects where the ID/PK isn't an integer. However in the scenario where a model does have a PK as an integer - this try/except quietly turns invalid URLs (eg. a string into an integer field) into a 404.

I think the immediate thought for most people would be along the lines of: fix your URLs to restrict/validate inputs.

However, if you've got a Django app that provides views/URLs for editing users, you have to make the URL patterns fairly relaxed to allow for multiple scenarios - one where a project stays with PK being an integer, and the other where a project has PK being a string. An example of this is Wagtail:

/admin/users/	wagtail.users.views.users.Index	wagtailusers_users:index
/admin/users/<str:pk>/	wagtail.users.views.users.Edit	wagtailusers_users:edit
/admin/users/<str:pk>/delete/	wagtail.users.views.users.Delete	wagtailusers_users:delete

Unless you wrap every view with a try/except in get_object, it's fairly easy to generate 500 errors (just visit /admin/users/hello/).

Should get_object handle these?

Should the functions in django.shortcuts also handle these?

[Mariusz Felisiak]

Should get_object handle these?

I don't think so, I've used class-based views in many projects and I've never needed it. This is not something that you will need unless you use some kind of models generalization. If you really need it, you can also implement your own mixin that will overwrite get_object().

Should the functions in django.shortcuts also handle these?

This idea has already been rejected (as you noticed).