Add res.redirect response helper (vercel#14705)

Co-authored-by: Tim Neutkens <tim@timneutkens.nl>

docs/advanced-features/preview-mode.md

@@ -111,8 +111,7 @@ export default async (req, res) => {
 
   // Redirect to the path from the fetched post
   // We don't redirect to req.query.slug as that might lead to open redirect vulnerabilities
-  res.writeHead(307, { Location: post.slug })
-  res.end()
+  res.redirect(post.slug)
 }
 ```
 

docs/api-routes/response-helpers.md

@@ -25,3 +25,4 @@ The included helpers are:
 - `res.status(code)` - A function to set the status code. `code` must be a valid [HTTP status code](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes)
 - `res.json(json)` - Sends a JSON response. `json` must be a valid JSON object
 - `res.send(body)` - Sends the HTTP response. `body` can be a `string`, an `object` or a `Buffer`
+- `res.redirect([status,] path)` - Redirects to a specified path or URL. `status` must be a valid [HTTP status code](https://en.wikipedia.org/wiki/List_of_HTTP_status_codes). If not specified, `status` defaults to "302" "Found".

packages/next/next-server/lib/utils.ts

@@ -225,6 +225,7 @@ export type NextApiResponse<T = any> = ServerResponse & {
    */
   json: Send<T>
   status: (statusCode: number) => NextApiResponse<T>
+  redirect: (statusOrUrl: string | number, url?: string) => NextApiResponse<T>
 
   /**
    * Set preview data for Next.js' prerender mode

packages/next/next-server/server/api-utils.ts

@@ -68,6 +68,7 @@ export async function apiResolver(
     apiRes.status = (statusCode) => sendStatusCode(apiRes, statusCode)
     apiRes.send = (data) => sendData(apiReq, apiRes, data)
     apiRes.json = (data) => sendJson(apiRes, data)
+    apiRes.redirect = (statusOrUrl, url) => redirect(apiRes, statusOrUrl, url)
     apiRes.setPreviewData = (data, options = {}) =>
       setPreviewData(apiRes, data, Object.assign({}, apiContext, options))
     apiRes.clearPreviewData = () => clearPreviewData(apiRes)
@@ -218,6 +219,26 @@ export function sendStatusCode(
   return res
 }
 
+/**
+ *
+ * @param res response object
+ * @param [statusOrUrl] `HTTP` status code of redirect
+ * @param url URL of redirect
+ */
+export function redirect(
+  res: NextApiResponse,
+  statusOrUrl: string | number,
+  url?: string
+): NextApiResponse<any> {
+  if (typeof statusOrUrl === 'string') {
+    url = statusOrUrl
+    statusOrUrl = 307
+  }
+
+  res.writeHead(statusOrUrl, { Location: url }).end()
+  return res
+}
+
 function sendEtagResponse(
   req: NextApiRequest,
   res: NextApiResponse,

test/integration/api-support/pages/api/redirect-301.js

@@ -0,0 +1,3 @@
+export default (req, res) => {
+  res.redirect(301, '/login')
+}

test/integration/api-support/pages/api/redirect-307.js

@@ -0,0 +1,3 @@
+export default (req, res) => {
+  res.redirect('/login')
+}

test/integration/api-support/test/index.test.js

@@ -236,6 +236,29 @@ function runTests(dev = false) {
     expect(data).toEqual({ message: 'Parsed body' })
   })
 
+  it('should redirect with status code 307', async () => {
+    const res = await fetchViaHTTP(appPort, '/api/redirect-307', null, {
+      redirect: 'manual',
+    })
+
+    expect(res.status).toEqual(307)
+  })
+
+  it('should redirect to login', async () => {
+    const res = await fetchViaHTTP(appPort, '/api/redirect-307', null, {})
+
+    expect(res.redirected).toBe(true)
+    expect(res.url).toContain('/login')
+  })
+
+  it('should redirect with status code 301', async () => {
+    const res = await fetchViaHTTP(appPort, '/api/redirect-301', null, {
+      redirect: 'manual',
+    })
+
+    expect(res.status).toEqual(301)
+  })
+
   it('should return empty query object', async () => {
     const data = await fetchViaHTTP(appPort, '/api/query', null, {}).then(
       (res) => res.ok && res.json()