[FIXED] condensing an async method into a one liner

Issue

I'm working on some async code for subscriptions / web sockets and have the following code after some effort. This in itself is functional.

@type(name="Subscription")
class ContactsSubscription:
    @subscription
    async def company(self, info: Info, pk: str) -> AsyncGenerator[CompanyType, None]:
        async for i in model_subscribe_publisher(info=info, pk=pk, model=Company):
            yield i

The part where I'm struggling is discovering how I can rewrite certain aspects to shorten this code even more and remove the repetitiveness out of the code for each model declaration through my 40-odd models in the app.

My goals would be to condense this into something like:

@type(name="Subscription")
class ContactsSubscrption:
    company: AsyncGenerator[CompanyType, None] = model_subscribe_publisher(Company)

I've seen this done in the same strawberry library, for queries:

@type(name="Query")
class ContactsQuery:
    company: CompanyType = node()

I fail to understand the magic that makes this work. How could I accomplish this?

Solution

There is no "magic" to make this work - the syntax you are using is that of a class decorator.

As you don't post the code for your type decorator, there is no way pointing what can be done - but it is a callable that gets the class, after ready, as a parameter: all one has to do is, inside the decorator call, to iterate over te class members and the class __annotations__, find out which members it want to place as new or replace, instantiate the new objects and assign then back to their names.

(That said, as I commented above, type is a poor choice for a class decorator name because it already has 3 different meanings in Python)

Or, if you don't want to change the class decorator, in your "desired" code, you just have to write a method that returns the model_subscribe_publisher as you want it:

ex.:

def subscriber_factory(model):
     async def subscriber_model_publisher(self, info, pk):
            async for item in model_subscribe_publisher(info=info, pk=pk, model=model):
                yield item
     return subscriber_model_publisher

@type(name="Subscription")
class ContactsSubscrption:
    company: AsyncGenerator[CompanyType, None] = subscriber_factory(Company)

Answered By - jsbueno