feat: initial relay integration support

[bellini666]

TODO:

• [x] Support for connections
• [x] Support for node()

[botberry]

Thanks for adding the RELEASE.md file!

Here's a preview of the changelog:

---

Initial relay connection/node support using Strawberry's relay integration.

[codecov-commenter]

Codecov Report

Merging #65 (d86b98f) into main (bf75e07) will increase coverage by 6.26%. Report is 1 commits behind head on main. The diff coverage is 89.69%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #65 +/- ## ========================================== + Coverage 78.45% 84.71% +6.26% ========================================== Files 10 14 +4 Lines 789 1590 +801 Branches 118 260 +142 ========================================== + Hits 619 1347 +728 - Misses 141 191 +50 - Partials 29 52 +23 ```

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #65 will not alter performance

_{Comparing bellini666:relay_integration (9ef9785) with main (af6a48c)}

Summary

✅ 1 untouched benchmarks

[erikwrede]

hey everyone, I still need some time to fully review this. Will get back when I have done some more testing

[bellini666]

Hey @erikwrede , @mattalbr

I just got back from djangocon and I'll get back to this PR during the weekend now.

One thing I was wondering here is regarding the fact that you need to have a session to query sqlalchemy objects.

Because of that I had to add a sessionmaker attribute to the fields, and I notice that the data loaders require one as well.

I was thinking about a way to avoid that and I have a proposal. Let me know what you think and I can implement that in this PR:

The idea is to use contextvars to provide a session that will be used during the execution of a query. Not only the relay fields I'm defining here can use it, but the dataloaders can also use it instead of requiring a bind argument.

Something like:

current_session = contextvars.ContextVar("current-session")

class SessionProviderExtension(SchemaExtension):
    def __init__(self, sessionmaker):
        self.sessionmaker = sessionmaker

    def on_execute(self):
        token = current_session.set(self.sessionmaker())
        try:
            yield
        finally:
            current_session.reset(token)

Of course we can also make the current_session be started lazely (create it when first accessing it)

What do you think?

[bellini666]

@mattalbr @erikwrede think I addressed all of the comments in this PR

Let me know if there's anything else missing to be able to merge this

[bellini666]

lgtm from my side, pending agreement on this from you:

Thank you! @mattalbr let me know if you want any extra changes in this