Improve APIRoute Typing

[jonathantneal]

Changes

This updates the APIRoute type to support specific Props, allowing authors to type routes more succinctly.

This is only a suggested improvement for authoring convenience. Typing without this change is provided below this example for comparison.

Example: /src/pages/content/[slug].js.ts:

import type * as TS from 'astro'

export interface Props {
  title: string
  content: string
}

export function getStaticPaths() {
  return [
    {
      params: {
        slug: 'some-slug',
      },
      props: {
        title: 'Some Title',
        content: 'Some content.',
      },
    }
  ]
}

With APIRoute:

export const get: APIRoute<Props> = ({ props }) => ({
  body: `export default ${JSON.stringify(props)}`,
})

Without APIRoute:

export const get = ({ props }: TS.APIContext<Props>): TS.EndpointOutput => ({
  body: `export default ${JSON.stringify(props)}`,
})

Testing

This change was tested by overriding the type locally.

Docs

/cc @withastro/maintainers-docs for feedback!