Fix rewriting to API routes not including query

packages/next/next-server/server/next-server.ts

@@ -561,7 +561,8 @@ export default class Server {
           const handled = await this.handleApiRequest(
             req as NextApiRequest,
             res as NextApiResponse,
-            pathname!
+            pathname!,
+            query
           )
           if (handled) {
             return { finished: true }
@@ -633,7 +634,8 @@ export default class Server {
   private async handleApiRequest(
     req: IncomingMessage,
     res: ServerResponse,
-    pathname: string
+    pathname: string,
+    query: ParsedUrlQuery
   ) {
     let page = pathname
     let params: Params | boolean = false
@@ -659,15 +661,17 @@ export default class Server {
 
     const builtPagePath = await this.getPagePath(page)
     const pageModule = require(builtPagePath)
+    query = { ...query, ...params }
 
     if (!this.renderOpts.dev && this._isLikeServerless) {
       if (typeof pageModule.default === 'function') {
+        this.prepareServerlessUrl(req, query)
         await pageModule.default(req, res)
         return true
       }
     }
 
-    await apiResolver(req, res, params, pageModule, this.onErrorMiddleware)
+    await apiResolver(req, res, query, pageModule, this.onErrorMiddleware)
     return true
   }
 
@@ -831,6 +835,18 @@ export default class Server {
     res.end(payload)
   }
 
+  private prepareServerlessUrl(req: IncomingMessage, query: ParsedUrlQuery) {
+    const curUrl = parseUrl(req.url!, true)
+    req.url = formatUrl({
+      ...curUrl,
+      search: undefined,
+      query: {
+        ...curUrl.query,
+        ...query,
+      },
+    })
+  }
+
   private async renderToHTMLWithComponents(
     req: IncomingMessage,
     res: ServerResponse,
@@ -854,15 +870,7 @@ export default class Server {
     if (!isSSG) {
       // handle serverless
       if (isLikeServerless) {
-        const curUrl = parseUrl(req.url!, true)
-        req.url = formatUrl({
-          ...curUrl,
-          search: undefined,
-          query: {
-            ...curUrl.query,
-            ...query,
-          },
-        })
+        this.prepareServerlessUrl(req, query)
         return result.Component.renderReqToHTML(req, res)
       }
 

test/integration/custom-routes/next.config.js

@@ -55,6 +55,18 @@ module.exports = {
           source: '/hidden/_next/:path*',
           destination: '/_next/:path*',
         },
+        {
+          source: '/api-hello',
+          destination: '/api/hello',
+        },
+        {
+          source: '/api-hello-regex/(.*)',
+          destination: '/api/hello?name=:1',
+        },
+        {
+          source: '/api-hello-param/:name',
+          destination: '/api/hello?name=:name',
+        },
       ]
     },
     async redirects() {

test/integration/custom-routes/pages/api/hello.js

@@ -0,0 +1 @@
+export default async (req, res) => res.json({ query: req.query })

test/integration/custom-routes/test/index.test.js

@@ -260,6 +260,23 @@ const runTests = (isDev = false) => {
     expect(res.headers.get('refresh')).toBe(`0;url=/`)
   })
 
+  it('should handle basic api rewrite successfully', async () => {
+    const data = await renderViaHTTP(appPort, '/api-hello')
+    expect(JSON.parse(data)).toEqual({ query: {} })
+  })
+
+  it('should handle api rewrite with un-named param successfully', async () => {
+    const data = await renderViaHTTP(appPort, '/api-hello-regex/hello/world')
+    expect(JSON.parse(data)).toEqual({
+      query: { '1': 'hello/world', name: 'hello/world' },
+    })
+  })
+
+  it('should handle api rewrite with param successfully', async () => {
+    const data = await renderViaHTTP(appPort, '/api-hello-param/hello')
+    expect(JSON.parse(data)).toEqual({ query: { name: 'hello' } })
+  })
+
   if (!isDev) {
     it('should output routes-manifest successfully', async () => {
       const manifest = await fs.readJSON(
@@ -476,6 +493,21 @@ const runTests = (isDev = false) => {
             ),
             source: '/hidden/_next/:path*',
           },
+          {
+            destination: '/api/hello',
+            regex: normalizeRegEx('^\\/api-hello$'),
+            source: '/api-hello',
+          },
+          {
+            destination: '/api/hello?name=:1',
+            regex: normalizeRegEx('^\\/api-hello-regex(?:\\/(.*))$'),
+            source: '/api-hello-regex/(.*)',
+          },
+          {
+            destination: '/api/hello?name=:name',
+            regex: normalizeRegEx('^\\/api-hello-param(?:\\/([^\\/]+?))$'),
+            source: '/api-hello-param/:name',
+          },
         ],
         dynamicRoutes: [
           {