support of async views

[yan-hic]

Similarly to Flask, the framework should support async function for a view - see https://flask.palletsprojects.com/en/2.1.x/async-await/
Under the hood, Flask executes asyncio.run() and returns the resulting value to the client.

When trying to define the view function with async, one gets TypeError: The view function did not return a valid response. The return type must be a string, dict, tuple, Response instance, or WSGI callable, but it was a coroutine.

Workaround is simply to create a "regular" sync function that executes (asyncio.run()) a separate async function but it could be simpler and match Flask functionality.

Our use case: use Google Cloud Functions from BigQuery Remote Function to call external APIs concurrently (using aiohttp).

[mikemykhaylov]

Is there any progress on this? I have a different use case (downloading and sending a file over the network, both function calls as coroutines), and a native support for async would be much appreciated compared to the asyncio.run() workaround.

[yan-hic]

Have a look at unsync library. We use it all the time now.

[xSAVIKx]

I believe this is somewhat blocked by the threads worker of Gunicorn used under the hood. And Gunicorn itself has had issues with async workers for a long time, but the latest v21 release should unblock a lot of different things.

IMO this one is blocked by #270 and #241