feat: allow use of Observables on subscriptions with generic-sdk

[onhate]

Allow the use of Observables on subscription operations for Generic SDK

config:
  usingObservableFrom: "import Observable from 'zen-observable';"
OR
  usingObservableFrom: "import { Observable } from 'rxjs';"

documents: '../**/document.graphql'
generates:
  ./index.ts:
    schema: '../**/schema.graphql'
    plugins:
      - typescript
      - typescript-operations
      - typescript-generic-sdk

Generates a method that returns an Observable instead of a Promise.

...
import Observable from 'zen-observable';
OR
import { Observable } from 'rxjs';
...

export function getSdk<C>(requester: Requester<C>) {
  return {
     ...
    onX(variables?: OnXVariables, options?: C): Observable<OnXSubscription> {
      return requester<OnXSubscription, OnXVariables>(OnXDocument, variables, options);
    }
  };
}

When this config is enabled, the Requester response will change to this:

export type Requester<C= {}> = <R, V>(doc: DocumentNode, vars?: V, options?: C) => Promise<R> | Observable<R>

This is an optional configuration that does not breaks existing setup.

[onhate]

it's still not clear for me how to extend the Requester type.

I'm thinking in adding an optional subscribe method to it and the invoke would be something like

requester<>.subscribe(...)

instead of

requester<>(...)

or

export type Requester<C= {}> = <R, V>(doc: DocumentNode, vars?: V, options?: C) => Promise<R> | Observable<R>

[onhate]

@dotansimha WDYT?

[dotansimha]

This is a great idea! Thank you for implementing this, @onhate !
I'll review it soon :)

[onhate]

hi @dotansimha and @ardatan, did you have the chance to review this PR?

[onhate]

@dotansimha, @ardatan ?

[onhate]

guys, any chance we could move this PR this week? @dotansimha @ardatan

[onhate]

@dotansimha @ardatan are you there?

[ardatan]

@onhate Thanks for the PR! LGTM!

[henrique-rotava]

Great implementation @onhate ! I was looking for some solution like that.

[dotansimha]

Thanks @onhate , it looks good.
Can you please move RawGenericSdkPluginConfig to a new file, called config.ts? It will simplify the process of creating auto-generated docs for that plugins.

Thank you :)

[onhate]

@dotansimha done!

[onhate]

@dotansimha, @ardatan is there any plan to make this available on npm soon?

[theguild-bot]

The latest changes of this PR are available as alpha in npm: 1.15.5-alpha-79d1efaa.0

Quickly update your package.json by running:

npx match-version @graphql-codegen 1.15.5-alpha-79d1efaa.0