Generated types

[Rich-Harris]

This code is a bit ratty, but I figured I'd push it up anyway. It generates .d.ts files for every page/endpoint file in src/routes (but tucked away in .svelte-kit via the magic of rootDirs). Easier to show than tell:

An eventual follow-up would be to automatically type Props (and the return value of a shadow endpoint, if no load function is given) based on a component's <script> tag.

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🦋 Changeset detected

Latest commit: 91e1a66

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@sveltejs/kit	Patch

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[Rich-Harris]

This is ready for review but lint is failing because pnpm check apparently runs before the test apps have been built (which creates the .svelte-kit/tsconfig.json files that pnpm check depends on). Not sure why, since the job includes pnpm build:

kit/.github/workflows/ci.yml

Lines 13 to 27 in eb7492f

	Lint:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- uses: pnpm/action-setup@v2.2.1
	with:
	version: 6.23.2
	- uses: actions/setup-node@v3
	with:
	node-version: '14.x'
	cache: pnpm
	- run: pnpm install --frozen-lockfile
	- run: pnpm build --filter ./packages --filter !./packages/create-svelte/templates
	- run: pnpm lint
	- run: pnpm check

Any ideas?

---

update: think i just needed to update pnpm-workspace.yaml

[pheuter]

Would it be fair to understand these changes as striving towards the direction of something like tRPC where you have the client being able to use types auto-generated from server endpoints?

[CoolOppo]

My tsconfig currently has this in it:
"extends": "@tsconfig/svelte/tsconfig.json",

Looking at the changes though, it appears I'm doing something wrong. How do I use the svelte-kit version?

[thenbe]

Would it be fair to understand these changes as striving towards the direction of something like tRPC where you have the client being able to use types auto-generated from server endpoints?

@pheuter It seems like it, to me at least, given that #647 is included in the 1.0 milestone.

Although, that may just be wishful thinking on my part. I recently added tRPC to my sveltekit app, in what I can only describe as the cherry to the delicious cake that is sveltekit. The effortless type safety has made what was already a ridiculously fun dev experience even better. Needless to say, I'd be pretty excited if sveltekit were to move in that direction.

And I mention tRPC in particular because of how simple or lightweight their approach is, which I feel aligns with svelte's own. In contrast, my original approach of implementing "end-to-end" typesafety was through graphQL. And while it could lead to the same result, the bloat accompanying graphQL quickly gets out of hand where you start questioning whether you're actually improving the dx at all. It ends up sticking out like a sore thumb alongside the simplicity of your typical sveltekit app.

P.S. I'm not an expert on the matter by any means, do take what I say with a grain of salt.

[BrettBedarf]

Is this intended to work the same for .ts files in addition to .js with jsdoc comments?

I am able to import the generated RequestHandler type from its full project path but not relative.

Minimal example: https://github.com/BrettBedarf/generated-types-minimal

/routes/ts/[slug].json.ts vs /routes/js/[slug].json.js

I think the issue is typescript trying to resolve the same file name does not "merge" the import

If I manually change the generated .d.ts file to [slug].json.gen.d.ts and change the import to import type { RequestHandler } from './[slug].json.gen'; I am able to use the type

[thenbe]

@BrettBedarf I'm seeing a similar issue. Eslint is reporting that the file is importing itself. It seems that an endpoints with a .ts extension wil try to import itself rather than importing it's generated types.

In the meantime, try the following workaround. Basically just add a .d to the import.

- import type { RequestHandler } from './[slug].json';
+ import type { RequestHandler } from './[slug].json.d';

[BrettBedarf]

@ambiguous48 good workaround thanks!

[TravisSpomer]

Is this intended to work the same for .ts files in addition to .js with jsdoc comments?

It doesn't seem so—seems like a really strange oversight. But you can hack it to work in TypeScript like this (at least for pages):

import type { Load } from "./filename"
export async function load({ params }: Parameters<Load>[0]): Promise<ReturnType<Load>>
{ /* ... */ }

If the generated types file exported LoadInput and LoadOutput then it would be a lot simpler.

[accuser]

Importing the RequestHandler in TypeScript works if you are explicit about the path:

import type { RequestHandler } from '.svelte-kit/types/src/routes/[slug]';

export const get: RequestHandler = async ({ params }) => {
  const { slug } = params;

I'm assuming that the rootDirs configuration in .svelte-kit/tsconfig.ts isn't working as expected.