Allow Edge Functions to receive body (#37822)

This PR enables Edge API endpoints to receive a body.
This wasn't in the original PR, as thankfully pointed out by @zaiste in [this comment](#37481 (comment)) 🙏

## Related

- Fixes #37821

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

packages/next/server/body-streams.ts

@@ -7,7 +7,7 @@ type BodyStream = ReadableStream<Uint8Array>
 /**
  * Creates a ReadableStream from a Node.js HTTP request
  */
-function requestToBodyStream(request: IncomingMessage): BodyStream {
+export function requestToBodyStream(request: IncomingMessage): BodyStream {
   const transform = new Primitives.TransformStream<Uint8Array, Uint8Array>({
     start(controller) {
       request.on('data', (chunk) => controller.enqueue(chunk))

packages/next/server/next-server.ts

@@ -81,7 +81,11 @@ import { urlQueryToSearchParams } from '../shared/lib/router/utils/querystring'
 import ResponseCache from '../server/response-cache'
 import { removeTrailingSlash } from '../shared/lib/router/utils/remove-trailing-slash'
 import { getNextPathnameInfo } from '../shared/lib/router/utils/get-next-pathname-info'
-import { bodyStreamToNodeStream, clonableBodyForRequest } from './body-streams'
+import {
+  bodyStreamToNodeStream,
+  clonableBodyForRequest,
+  requestToBodyStream,
+} from './body-streams'
 import { checkIsManualRevalidate } from './api-utils'
 
 const shouldUseReactRoot = parseInt(React.version) >= 18
@@ -1495,8 +1499,9 @@ export default class NextNodeServer extends BaseServer {
           name: params.page,
           ...(params.params && { params: params.params }),
         },
-        // TODO(gal): complete body
-        // body: originalBody?.cloneBodyStream(),
+        body: ['GET', 'HEAD'].includes(params.req.method)
+          ? undefined
+          : requestToBodyStream(params.req.originalRequest),
       },
       useCache: !this.nextConfig.experimental.runtime,
       onWarning: (_warning: Error) => {

test/e2e/edge-api-endpoints-can-receive-body/app/pages/api/edge.js

@@ -0,0 +1,11 @@
+export default async (req) => {
+  if (!req.body) {
+    return new Response('Body is required', { status: 400 })
+  }
+
+  return new Response(`got: ${await req.text()}`)
+}
+
+export const config = {
+  runtime: 'experimental-edge',
+}

test/e2e/edge-api-endpoints-can-receive-body/index.test.ts

@@ -0,0 +1,35 @@
+import { createNext, FileRef } from 'e2e-utils'
+import { NextInstance } from 'test/lib/next-modes/base'
+import { fetchViaHTTP } from 'next-test-utils'
+import path from 'path'
+
+describe('Edge API endpoints can receive body', () => {
+  let next: NextInstance
+
+  beforeAll(async () => {
+    next = await createNext({
+      files: {
+        'pages/api/edge.js': new FileRef(
+          path.resolve(__dirname, './app/pages/api/edge.js')
+        ),
+      },
+      dependencies: {},
+    })
+  })
+  afterAll(() => next.destroy())
+
+  it('reads the body as text', async () => {
+    const res = await fetchViaHTTP(
+      next.url,
+      '/api/edge',
+      {},
+      {
+        body: 'hello, world.',
+        method: 'POST',
+      }
+    )
+
+    expect(res.status).toBe(200)
+    expect(await res.text()).toBe('got: hello, world.')
+  })
+})