Support async generators in StreamingHttpResponse

[Axel Hecht]

The DEP for async menytions that async generators should be supported in StreamingHttpResponse.

After some digging, it seems that at least StreamingHttpResponse itself and ASGIHandler.send_response need changes to support that?

[Carlton Gibson]

Yes, this is probably something we should take as a new feature, but it's a little undefined at the moment.

Can I point you to the Forum Async topic: ​https://forum.djangoproject.com/c/internals/async/8https://forum.djangoproject.com/c/internals/async/8
That's a good place to discuss it, and get fleshed out what would be required.

I'll cc Andrew, as maybe he already has thoughts.

[Andrew Godwin]

We definitely should expand to add this, but async generators are quite tough to support across a range of Python versions; they get increasingly better to use every version. I think the best approach here would be an exploratory patch to see what we can get that looks reasonable given Django's current supported Python versions - 3.6 might be a high enough baseline (3.5 is very problematic), but it might be a thing that's easier in a future 3.7+ release.

[Tim Graham]

#34300 requested this again, pointing to an implementation at ​​https://pypi.org/project/django-async-stream/.

[Simon Charette]

Isn't this supported in 4.2 via (0bd2c0c9015b53c41394a1c0989afbfd94dc2830) #33735?