refactor(nuxt): enhance useFetch and useLazyFetch request type

[didavid61202]

Updates

• awaiting fix in nitro for NitroFetchRequest type to support string type (Fix NitroFetchRequest type to support string type nitrojs/nitro#225)
  update at 2022/5/11

• updated this PR according to unjs/nitro's new NitroFetchRequest type (enhance $fetch's request type infer from generated InternalApi interface nitrojs/nitro#208)
  update at 2022/5/11

• Implementing this enhancement in the unjs/nitro repo for $fetch first (enhance $fetch's request type infer from generated InternalApi interface nitrojs/nitro#208), and will update this PR accordingly.
  update at 2022/5/7

---

Enhance the useFetch and useLazyFetch request's type by inferring nitropack's server route's string literal (InternalApi interface). supporting auto-complete and showing type hints.

🔗 Linked issue

Resolve nuxt/nuxt#13934

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Enhance the useFetch and useLazyFetch request's type by inferring nitropack's server route's string literal (InternalApi interface).

This will provide better DX and prevent typos while using useFetch and useLazyFetch by supporting auto-complete and showing type hints when entering the request. And should still be able to pass other valid request URLs like https://example.com/api or Request object like new Request('/api/test')

Usage scenario

assume project contains server/api/test.ts

import type { NitroFetchRequest } from 'nitropack'

const { data } = useFetch(/** IDE should show hint: '/api/test' */)

const request: NitroFetchRequest = /** IDE should show hint: '/api/test' */

useFetch('/api/test') // ok
useFetch('https://example.com/api') // ok
useFetch(new Request('api/test')) // ok

useFetch(/** will not show internal routes ex: '__nuxt_error' */)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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[Rigo-m]

One thing that's missing is the ability to type POST request body, is there a way to implement it?

[didavid61202]

One thing that's missing is the ability to type POST request body, is there a way to implement it?

@Rigo-m I'll look into this!

[Rigo-m]

Sorry that I can't help, I'm still bad a TS somehow hahaha

[didavid61202]

Sorry that I can't help, I'm still bad a TS somehow hahaha

Got a working code that infers the body type of a POST API, but still needs to manually export the type from the API file and change the auto-generated InternalApi interface, or have to make some change to nitropack (and maybe h3) to make the implementation cleaner.
I would have to discuss this with @danielroe or other core team members about this for code organization and naming consistency. then do another issue/PR.

hacky method

// .nuxt/types/nitro.d.ts
declare module 'nitropack' {
  type Awaited<T> = T extends PromiseLike<infer U> ? Awaited<U> : T
  interface InternalApi {
// turn value of InternalApi in to tuple, with index 1 being the body type
    '/api/test': [Awaited<ReturnType<typeof import('../../server/api/test').default>>, import('../../server/api/test').BodyType]
    '/__nuxt_error': [Awaited<ReturnType<typeof import('../../../packages/nuxt/src/core/runtime/nitro/renderer').default>>,'']
  }
}

// server/api/test.ts
export type BodyType = {tag:string, index:number } // export the manually defined type

export default defineEventHandler(async (event) => {
  const body = await useBody<BodyType>(event)
  return { result: body.tag }
})

// composable/fetch.ts
export declare type FetchRequestUrl =
  Exclude<keyof InternalApi, '/__nuxt_error'>
  | (`${string}${'/'|'.'}${string}` & {})
  | Exclude<FetchRequest, string>
interface ExFetchOptions<Route extends FetchRequestUrl> extends FetchOptions {
  body?: Route extends keyof InternalApi ? InternalApi[Route][1] : FetchOptions['body']
}
export interface UseFetchOptions<
  DataT,
  ReqT extends FetchRequestUrl,
  Transform extends _Transform<DataT, any> = _Transform<DataT, DataT>,
  PickKeys extends KeyOfRes<Transform> = KeyOfRes<Transform>
> extends AsyncDataOptions<DataT, Transform, PickKeys>, ExFetchOptions<ReqT> {
  key?: string
}

// usage
const { data } = useFetch('/api/test', { // have to update nitropack's type to correctly infer data type
  method: 'POST',
  body: { tag: '3', index: 2 } // body will be type 'BodyType '
})

[Rigo-m]

Maybe a clean solution could be manually typing body by extending nuxt schema like we do for manually tiping useRuntimeConfig?

[danielroe]

I love this idea. I think rather than seeking to implement within useFetch within Nuxt we should do so within nitropack which is where the rest of the $fetch inference comes from: https://github.com/unjs/nitro/blob/4fbeef9bfd5c8e064817865a31d61927addc5e2a/src/types/fetch.ts

... and then update this PR accordingly.

WDYT @pi0?

[pi0]

I also love to try this idea! Indeed nitro seems better place to implement types for $fetch.

[didavid61202]

I love this idea. I think rather than seeking to implement within useFetch within Nuxt we should do so within nitropack which is where the rest of the $fetch inference comes from: https://github.com/unjs/nitro/blob/4fbeef9bfd5c8e064817865a31d61927addc5e2a/src/types/fetch.ts

... and then update this PR accordingly.

WDYT @pi0?

Sounds great! I implement it in Nuxt first as I wasn't sure if this should be implemented in nitropack. But after some digging and trying to implement type hint for POST body yesterday, I also found out that the codes to updates are mostly in nitropack.

mainly:

1. move this PR's new FetchRequestUrl type into nitropack
2. the structure of the InternalApi interface: except for the default return of server function, we can also expose the request's body type...etc as a Map type for future expansion? (as name export in server files or update defineEventHandlers signature)

I'll find some time to dig into it 👍

[didavid61202]

I love this idea. I think rather than seeking to implement within useFetch within Nuxt we should do so within nitropack which is where the rest of the $fetch inference comes from: https://github.com/unjs/nitro/blob/4fbeef9bfd5c8e064817865a31d61927addc5e2a/src/types/fetch.ts
... and then update this PR accordingly.
WDYT @pi0?

Sounds great! I implement it in Nuxt first as I wasn't sure if this should be implemented in nitropack. But after some digging and trying to implement type hint for POST body yesterday, I also found out that the codes to updates are mostly in nitropack.

mainly:

1. move this PR's new FetchRequestUrl type into nitropack
2. the structure of the InternalApi interface: except for the default return of server function, we can also expose the request's body type...etc as a Map type for future expansion? (as name export in server files or update defineEventHandlers signature)

I'll find some time to dig into it 👍

Hey, @danielroe @pi0 would like to get some suggestions/notices (if any) on point 2 before I start, for changing the InternalApi interface and defineEventHandlers signature.
And if we want to auto infer Body type by using useBody, we might also have to update h3?
Thanks in advance ❤️

[didavid61202]

Update

Implementing this enhancement in unjs/nitro repo first (nitrojs/nitro#208), and will update this PR accordingly.

[pi0]

@didavid61202 Since nitrojs/nitro#208 is landed, do you mind to rework this PR? Thanks!

[didavid61202]

I'm on it! 🚀

[pi0]

and I was wondering if we should exclude the /__nuxt_error path from NitroFetchRequest, or still let user sees it?
maybe we could also rename and export the Request type by FetchRequest or NuxtFetchRequest, any suggestion? 😃

I would hide all /_* and /api/_* routes from auto completion as they are internal.

[didavid61202]

and I was wondering if we should exclude the /__nuxt_error path from NitroFetchRequest, or still let user sees it?
maybe we could also rename and export the Request type by FetchRequest or NuxtFetchRequest, any suggestion? 😃

I would hide all /_* and /api/_* routes from auto completion as they are internal.

updated in b49385c, excluding all /_* and /api/_* routes and export/alias NitroFetchRequest to FetchRequest

[pi0]

@didavid61202 Maybe we can move this fix directly to Nitro and avoid workaround? I can quickly merge it for nitro and this after that :)

[didavid61202]

@didavid61202 Maybe we can move this fix directly to Nitro and avoid workaround? I can quickly merge it for nitro and this after that :)

sure, on it!
and how is the alias's nameing? adding Nuxt prefix? or keep it as FetchRequest?

[danielroe]

Looking great! There were a couple of workarounds in 7e89fe8 that I think we can now remove as well, if you're up for it 😊

[pi0]

and how is the alias's nameing? adding Nuxt prefix? or keep it as FetchRequest?

Can we directly use NitroFetchRequest everywhere? It reduces chances of inconsistent typings.

[didavid61202]

sure, on it! will see what I can do 👍

[didavid61202]

and how is the alias's nameing? adding Nuxt prefix? or keep it as FetchRequest?

Can we directly use NitroFetchRequest everywhere? It reduces chances of inconsistent typings.

got it!
@pi0 fixed in nitrojs/nitro#232 👍

[pi0]

Thanks for working on this @didavid61202 @danielroe <3