[Proposal] [TypeScript] prefer interface to conditional types

[shigma]

interface PayloadMap {
  'check_run': WebhookPayloadCheckRun
  'check_run.completed': WebhookPayloadCheckRun
  ...
}

type AllEvents = keyof PayloadMap | 'error' | '*'

export declare type GetWebhookPayloadTypeFromEvent<E = AllEvents, T = WebhookEvent> =
  E extends 'error' ? WebhookEventHandlerError :
  E extends '*' ? any :
  WebhookEvent<PayloadMap[E]> & T

This will not only help reduce dist size but also optimize type check performance.

[gr2m]

Thansk @shigma! I'm curious about "optimize type check performance", could you elaborate?

@dominguezcelada do you have any opinion? Maybe @shigma can start a pull request so we can test the changes and discuss in detail?

[oscard0m]

Thansk @shigma! I'm curious about "optimize type check performance", could you elaborate?

@dominguezcelada do you have any opinion? Maybe @shigma can start a pull request so we can test the changes and discuss in detail?

Let me take a look into it tomorrow.

Also mentioning @ankeetmaini in case you have time to take a look and you want to participate :)

[ankeetmaini]

This looks really cool! I think we can remove the generic parameter T too as it's not used inside the type. But this looks like a much improved way to do this :)

[ankeetmaini]

Is it just me or the ts types are showing any for any event in the project?

Will dig this and see if I can find out why.

[gr2m]

Is it just me or the ts types are showing any for any event in the project?

It's not just you, see #279.

[gr2m]

I had a call with @andrewbranch about types in @octokit/webhooks. Andrew is working on TypeScript at Microsoft.

We talked about how we can define Types in a way that consumers could extend them with custom events, in order to address #277. What we would like to allow is something like this:

declare "@octokit/webhooks" {
  interface Events {
    "my_custom_event": MyCustomEventPayload
  }
}

I think that is very similar to what @shigma suggests, and we would not only simplify our TypeDefinitions and make them more efficient, but also allow for custom types.

@andrewbranch - did I get this right?

@ankeetmaini has a work inprogress PR here: #258

[gr2m]

I gave this some more thought, and I think I'd actually prefer what express is doing by defining a global namespace, see https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/express-serve-static-core/index.d.ts#L17-L25

The reason for that is that it is possible that these type definitions will move to other packages in future, e.g. an @octokit/events package or @octokit/types. My understanding is that this would require changes to the declare "@octokit/webhooks" blocks, while the global namespace approach would always work

declare namespace Octokit {
    export interface Events {
        "my_custom_event": MyCustomEventPayload
    }
}

[github-actions]

🎉 This issue has been resolved in version 7.12.1 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

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