Allow lazy translation strings in email contexts

[realsuayip]

No description provided.

[sobolevn]

Sorry, I cannot find any mentions of this in either:

• https://docs.djangoproject.com/en/4.2/topics/email/
• https://github.com/django/django/blob/main/django/core/mail/message.py

Can you please point to exact places in the docs / source?

[realsuayip]

I could not find a reference to it either. However, I think it is a valid (and common) use case. In my experience, any user-facing string tends to be translatable in Django, and in the case they are not, some exception is raised, making it necessary to use force_str.

[sobolevn]

@adamchainz can you please take a look?

[intgr]

It has been many years since I used translations in Django, but for back when I used them, my experience matches realsuayip's description:

In my experience, any user-facing string tends to be translatable in Django

The relevant documentation is https://docs.djangoproject.com/en/4.2/topics/i18n/translation/#working-with-lazy-translation-objects, quote:

The result of a gettext_lazy() call can be used wherever you would use a string (a str object) in other Django code, but it may not work with arbitrary Python code.

I think the Django documentation overstates it, reality is more nuanced. Obviously, there are str params for machine identifiers (e.g. IntegerField(db_column=_("translate this")) or .prefetch_related(_("translate this"))) that don't reasonably support lazy translations. But for user-readable message strings like email titles, the Django intends to allow lazy strings everywhere.

[intgr]

I looked at the Django code, but it's not straightforward. @realsuayip have you tested that these functions work with lazy strings?

As described in my previous message, I'm inclined to accept this PR, but I'll leave final decision to sobolevn.

[realsuayip]

@intgr Yes, eventually all functions end up creating EmailMessage instances, which itself handles translatable strings.

[sobolevn]

Yes, looks like it works locally! Thanks everyone!