Type Helpers

[BoilerTom90]

I found the need in my angular app to use the apolloCache.updateQuery function. I wrote a small wrapper to the function so that it can be called and use for any of our queries. However, it's currently not type safe.

My updateQuery wrapper is currently only going to work for one of our graphql queries, such as this one:

@Injectable({
	providedIn: 'root'
})
export class MyQuery extends Apollo.Query<
	MyOpResult,
	MyVars
> {
	override document = MyQueryDoc;
	override client = 'myApi';
	constructor(apollo: Apollo.Apollo) {
		super(apollo);
	}
}

My updateQuery wrapper assumes the structure of the OpResult, MyVars and MyQueryDoc. What I'd like to be ale to do is create some typescript type helps that given a specific MyQuery, it can extract or infer MyOpResult, MyVars, and MyQueryDoc, and I can then use those types to provide some type safety to my updateQuery wrapper.

Two questions:

1. are any utility types available in the apollo library to assist with this? I can't see to find any.
2. I've tried creating my own utility types, but I'm struggling getting it to work. even trying to get the type of MyOpResult doesn't seem to work.

type OpResult<T> = T extends Apollo.Query<infer R, infer V> ? R : never;
type QueryOpResultType = OpResult<MyQuery>; 
// always returns a type of "never"