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RequestEvent and RequestHandlerOutput should be public shapes #4138

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cdcarson opened this issue Feb 26, 2022 · 2 comments · Fixed by #4519
Closed

RequestEvent and RequestHandlerOutput should be public shapes #4138

cdcarson opened this issue Feb 26, 2022 · 2 comments · Fixed by #4519
Labels
feature / enhancement New feature or request types / typescript
Milestone
1.0

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@cdcarson
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Describe the problem

This change moved RequestEvent and EndpointOutput into kit/types/private.d.ts from kit/types/index.d.ts, making them "private" rather than reliable.

These two types in particular seem to define the basic contract for endpoints. You get a RequestEvent, you return an EndpointOutput. Unless this contract is going to change radically these types should be made public again.

Describe the proposed solution

Make RequestEvent and EndpointOutput public.

Alternatives considered

  • Keep using the RequestEvent and EndpointOutput types, even though they are ostensibly private.
  • Use the generics given to RequestHandler<Params = Record<string, string>, Output extends Body = Body> . A note about this. The Params generic is of no use to me in userland (though maybe I don't understand it.) For an endpoint at /foo/[fooId] it should be a given that const { fooId } = event.params will always work, be a non-empty string, etc. Is this something internal / adapter-specific that leaked out into the public API?

Importance

would make my life easier

Additional Information

No response
@cdcarson
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Relatedly, the shape of EndpointOutput (now RequestHandlerOutput) changed to a MaybePromise. Specifically, the MaybePromise part has been bumped down to RequestHandlerOutput from the RequestHandler function type.

I couldn't find this in the changelog, but here's the commit.

This causes a problem at least in typescript.

import type { RequestHandler, RequestHandlerOutput } from '@sveltejs/kit';

/** 
 * The way one would expect it to work. Error:
 * The return type of an async function or method must be the global Promise<T> type. 
 */
export const get: RequestHandler = async ({request}): RequestHandlerOutput => {
  // do something async here
  return {
    status: 200
  };
}

/**
 * For completeness, I tried returning a promise of a maybe promise.
 * Error: (verbose, basically, that a Promise is not a RequestHandlerOutput)
 * Type '({ request }: RequestEvent<Record<string, string>>) => Promise<RequestHandlerOutput<Body>>' 
 * is not assignable to type 'RequestHandler<Record<string, string>, Body>'. Blah blah blah...
 */
export const post: RequestHandler = async ({request}): Promise<RequestHandlerOutput> => {
  // do something async here
  return {
    status: 200
  }
}

The simple way to fix this is to move the MaybePromise thing back up to RequestHandler type, where it probably belongs. (The function is sync | async, not the output.)

@benmccann benmccann added this to the 1.0 milestone Feb 27, 2022
@Rich-Harris Rich-Harris changed the title RequestEvent and EndpointOutput should be public shapes RequestEvent and RequestHandlerOutput should be public shapes Mar 2, 2022
@benmccann benmccann added the feature / enhancement New feature or request label Mar 17, 2022
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@Rich-Harris Rich-Harris mentioned this issue Apr 5, 2022
Merged
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@MonoAnji
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I'm a bit confused why this is closed now even though it's still an issue, I still get warnings when defining hook functions and request handlers because i cannot define the event parameter by it's actual type, which is RequestEvent

consider the following hooks.ts:

import type {GetSession, RequestEvent} from "@sveltejs/kit";

export const getSession: GetSession = async (event: RequestEvent) => {
  //Do anything here where you'd want to use the event with actual type information
}

At least in IntelliJ Idea this yields

TS2459: Module '"@sveltejs/kit"' declares 'RequestEvent' locally, but it is not exported.  index.d.ts(18, 2): 'RequestEvent' is declared here.

Which is correct. So am I not supposed to declare the type of the event parameter? I'd like to.

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feature / enhancement New feature or request types / typescript
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move MaybePromise from RequestHandlerOutput to RequestHandler return value sveltejs/kit
3 participants
@cdcarson @benmccann @MonoAnji