Appkey is not defined in the handlers. about aiohttp HOT 9 CLOSED

I've opened a discussion to see if there's anything we can do in the future:
python/typing#1543

from aiohttp.

The key is the instance, not the name/type.

So, you need to save the key somewhere globally and reuse it across the project.

from aiohttp.

We can probably make this clearer in the docs, but you'll see all the examples use a variable, rather than creating a new instance when indexing.

from aiohttp.

Thank you for the answer, but what is supposed to do when the handlers are defined in a different module than the server initialization?
Should the "standard" define all the app keys in a module and import them both in the module that initiates the server and in the handlers modules?

from aiohttp.

Yes, there needs to be a canonical location. For projects, I typically put them in typedefs.py or similar (along with typing aliases etc.). Between different projects, it needs to be imported, for example see aiohttp-jinja2:

The static function has similar usage, except it requires you to set app[aiohttp_jinja2.static_root_key].

app = web.Application()
app[aiohttp_jinja2.static_root_key] = "/static"

https://aiohttp-jinja2.readthedocs.io/en/latest/#default-globals

And we use that key, for example, in aiohttp-devtools:
https://github.com/aio-libs/aiohttp-devtools/blob/master/aiohttp_devtools/runserver/serve.py#L28

from aiohttp.

Ok, I will do it, thank you so much for the fast answer!

from aiohttp.

Hey @Dreamsorcerer, I was making this migration but there are some cases where the value that I want to store an AppKey is a callable (for instance a partial that is completed with the remaining args in the handler). However when I do:

some_key = AppKey("some_key", Callable[[type_arg1, type_arg2], return_type])

Mypy is not very happy saying:
error: Argument 2 to "AppKey" has incompatible type "object"; expected "type[Never] | None"

from aiohttp.

See the examples in the docs for the alternative syntax. i.e. It'll work with AppKey[Callable]("some_key"). The problem is that things like Callable are not types, but we don't want to annotate it as allowing anything and have mistakes like AppKey(..., 5). I'm not sure if there is a better annotation to make this work.

from aiohttp.

Thanks!

from aiohttp.