Implement `Session.__bool__`

[Jake Howard]

It's often useful to check whether the user has a session, for example to avoid creating one unnecessarily. Since request.session is always populated when SessionMiddleware is used, it's better to check whether the session is empty.

#36898 documents Session.is_empty() which achieves this, but it could also be nice if Session supported a boolean check directly through __bool__, which would just call is_empty internally.

This would mean if request.session works as expected. The downside being if getattr(request, "session", None) would be False when sessions are being used, but the session is empty (arguably hasattr would be better there anyway).

[Ahmed Asar]

Hi, I'd like to work on this ticket and submit a patch if that's okay.
Please let me know if there’s anything specific I should consider.
Thanks!

[Natalia Bidart]

Thank you Jake, I think the request makes sense. Personally I would have suggested a single ticket for this and documenting is_empty, but I see Jacob prefers otherwise so +1 from me.

[Jacob Walls]

Jake, any thought about how/where to doc this? Minor incompatible change? Doubt we want a deprecation path.

[Ahmed Asar]

Hi Amar,
I just wanted to mention that I had commented earlier expressing interest in working on this ticket.
If you’re already planning to take it, no worries at all 👍
But if you’re open to it, I’d be happy to work on the patch and submit a PR.
Thanks!

[Amar]

Hi Ahmed,

Thanks a lot for your interest in this ticket, and sorry about the timing — I didn’t notice your earlier comment before picking it up.

I’ve already worked on a patch and submitted a PR for this ticket here:
​https://github.com/django/django/pull/20631

[Natalia Bidart]

Amar, you can not set the flag "Ready for Checkin" in your own PR, please read carefully the contributing docs.

[Tim Graham]

The PR has an approval from Jake.

[Amar]

Sorry about that, Natalia. I saw Jake's approval on the PR and figured the Trac status update had just been missed, so I jumped the gun trying to be helpful.
I’ll make sure to leave the triage flags to the fellows from now on.
Thanks for the catch, and thanks Tim for the follow-up.

[Jacob Walls <jacobtylerwalls@…>]

In 158fd81:

Fixed #36899 -- Implemented SessionBase.bool.