Admin change list swallows unrelated AttributeErrors from callable display fields

[Pi Delport]

If a callable display field on a model or model admin raises either an AttributeError, the interface currently captures the error, and renders the field as EMPTY_CHANGELIST_VALUE.

This behavior is surprising and confusing when the AttributeError originates in unrelated user code called by the display field: errors like third-party app bugs or missing settings get silenced, and the field's content simply becomes "(None)". There's no hint to a novice about what went wrong, or where to look next.

The code responsible for this is in ​templatetags/admin_list.py's items_for_result(), around lookup_field(). As far as i can tell, all the valid empty fields cases are covered by results of ObjectDoesNotExist or None, and not AttributeError: a missing attribute specified in list_display normally result in ImproperlyConfigured instead.

If there's no compelling reason to capture AttributeError like this, can it simply be removed from the exception list, and allowed to propagate?

[Pi Delport]

I added a fix and regression test for this on GitHub: ​#193.

It turns out the test suite itself contained a latent bug that was being masked by this: the above patch fixes that too.

[Pi Delport]

I found an older ticket for this same bug: #16655.

From the comments, the proposed change was discussed and accepted back then, but needed a test: does this patch resolve that?

[Aymeric Augustin]

Fixed in [617d077f].