Added generic type for body in NextApiRequest

[Nirzhuk]

Generic Type for the body in NextApiRequests to implement your custom interfaces to handle better the data.

[ijjk]

Stats from current PR

Default Server Mode

General Overall increase ⚠️

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
buildDuration	12s	11.5s	-486ms
nodeModulesSize	66.5 MB	66.5 MB	⚠️ +14 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.065	2.03	-0.04
/ avg req/sec	1210.49	1231.3	+20.81
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.311	1.323	⚠️ +0.01
/error-in-render avg req/sec	1907.44	1889.77	⚠️ -17.67

Client Bundles (main, webpack, commons)

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
main-HASH.js gzip	6.72 kB	6.72 kB	✓
webpack-HASH.js gzip	751 B	751 B	✓
19b7e98f51cc..cead.js gzip	9.77 kB	9.77 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	56.4 kB	56.4 kB	✓

Client Bundles (main, webpack, commons) Modern

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
main-HASH.module.js gzip	5.79 kB	5.79 kB	✓
webpack-HASH..dule.js gzip	751 B	751 B	✓
19b7e98f51cc..dule.js gzip	6.17 kB	6.17 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	51.9 kB	51.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
polyfills-HASH.js gzip	26.4 kB	26.4 kB	✓
Overall change	26.4 kB	26.4 kB	✓

Client Build Manifests

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
_buildManifest.js gzip	267 B	267 B	✓
_buildManife..dule.js gzip	273 B	273 B	✓
Overall change	540 B	540 B	✓

Rendered Page Sizes

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
index.html gzip	955 B	955 B	✓
link.html gzip	962 B	962 B	✓
withRouter.html gzip	947 B	947 B	✓
Overall change	2.86 kB	2.86 kB	✓

---

Serverless Mode

General Overall increase ⚠️

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
buildDuration	12.7s	12.7s	-41ms
nodeModulesSize	66.5 MB	66.5 MB	⚠️ +14 B

Client Bundles (main, webpack, commons)

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
main-HASH.js gzip	6.72 kB	6.72 kB	✓
webpack-HASH.js gzip	751 B	751 B	✓
19b7e98f51cc..cead.js gzip	9.77 kB	9.77 kB	✓
framework.HASH.js gzip	39.1 kB	39.1 kB	✓
Overall change	56.4 kB	56.4 kB	✓

Client Bundles (main, webpack, commons) Modern

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
main-HASH.module.js gzip	5.79 kB	5.79 kB	✓
webpack-HASH..dule.js gzip	751 B	751 B	✓
19b7e98f51cc..dule.js gzip	6.17 kB	6.17 kB	✓
framework.HA..dule.js gzip	39.1 kB	39.1 kB	✓
Overall change	51.9 kB	51.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
polyfills-HASH.js gzip	26.4 kB	26.4 kB	✓
Overall change	26.4 kB	26.4 kB	✓

Client Build Manifests

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
_buildManifest.js gzip	267 B	267 B	✓
_buildManife..dule.js gzip	273 B	273 B	✓
Overall change	540 B	540 B	✓

Serverless bundles

	vercel/next.js canary	Nirzhuk/next.js next_api_request_generic_type_body	Change
_error.js	881 kB	881 kB	✓
404.html	4.17 kB	4.17 kB	✓
hooks.html	3.79 kB	3.79 kB	✓
index.js	881 kB	881 kB	✓
link.js	923 kB	923 kB	✓
routerDirect.js	917 kB	917 kB	✓
withRouter.js	917 kB	917 kB	✓
Overall change	4.53 MB	4.53 MB	✓

Commit: 310e7b4

[lfades]

Hi there @Nirzhuk thank you for the PR, I'm going to close the PR as this change is not required for the following reason:

body can be anything, it's value doesn't depend on the API route but on the request, if you want to type it do it after doing an actual validation on top of it, otherwise the type will do more harm than good, that's a similar reasoning to why req.query doesn't accept a custom type either.

For example:

function validate(body: any) {
  // ...
  return body as MyType
}

// ...
const body = validate(req.body)

In the above example your code will properly set the type, and only after validating that such type is correct.

[Nirzhuk]

@lfades Thanks for answering.
In the code what you wrote affects directly to the bundle adding maybe 1-3kb for every request you need to handle custom type. So I don't feel it's better to handle that way, but you're know better than me what NextJS needs, so thanks again for your time answering the PR.