Exposing Mypy-compatible type information

[ktosiek]

I'd like to use Mypy for checking a Graphene-based app. Is anyone working on stubs, or even better - a Mypy plugin?

What I imagine is writing:

class Me(ObjectType[User]):
    full_name = graphene.String()
    def resolve_full_name(self, info):
        return self.get_full_name()

And getting a guarantee that User.get_full_name() returns something assignable to Optional[String].

[ktosiek]

Looks like this might not be possible - Plugin.get_function_hook can override the type of full_name, and Plugin.get_subclass_hook can look at types of actual methods, but I haven't found a way to make those two communicate.

An approach closer to #729 (comment) seems to make more sense - this way everything to know about a resolver lives in one place.

[dvndrsn]

From my understanding, much (if not all) of the Graphene and graphql-core codebase is type hinted with Python 2.7 style annotations, but all of the user generated types have attributes through some metaprogramming, which can be a challenge to generate stubs for. There's a mypy issue here discussing a similar topic:

python/mypy#1310

[ktosiek]

Those type hints are not exported, see this PEP-561 section. And as you've noted, they don't cover that much of user's code.

For the metaprogramming part a plugin would be needed. I've looked into it, but I'm not sure how to tie field declarations with types of resolvers (maybe we'll need a new mypy hook?).

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[ckarnell]

Hi all, I created a repo for stubs for this library and wrote a plugin for it to match resolver function definitions to their corresponding Field attributes. Feel free to use / file issues / contribute!

https://github.com/trialspark/graphene-stubs

[PureTryOut]

That packages hasn't seen an update since March 2020, only 2 months after it was announced here. It would be great if mypy itself can export type hints, can this issue be re-opened?

[ryanovas]

Would also like to see this re-opened

[tekhenu]

Bump. This is still a problem.