Can't use custom formats with new language-independent LogEntry's messages in Django 1.10

[Ivan Tsouvarev]

Say, you have some model, which __str__ uses django.utils.formats.date_format with custom format string.

settings.FORMAT_MODULE_PATH contains module, in which this string is defined.

So, when you create object of this model via admin interface, the following things happen:

1. Django calls construct_change_message to create LogEntry, which is decorated with @translation_override(None), which will deactivate current language
2. To write object representation with custom format in change message, django.utils.formats.get_format will be called
3. get_format will try to find custom format, but it can't be done when active language is None, so original string will be returned as-is
4. django.utils.dateformat.format will interpret custom format string literally, which may not fail with exception, but will be totally wrong anyway

[Tim Graham]

Do you have any suggestions about how to fix that?

[Ivan Tsouvarev]

Hard to say. May be there is a way to avoid translation without deactivating current language?

[Claude Paroz]

I don't see a proper solution yet, apart from providing some default yourself by comparing the get_format return value.

[Tim Graham]

Feel free to reopen if someone thinks of a proposal of how Django could facilitate this use case.