Ensure initialHeaders are normalized (#49643)

This makes sure we have the initial headers in the correct shape during build. Fixes: #49374
vercel · May 11, 2023 · bc4515d · bc4515d
1 parent e6d50ec
commit bc4515d
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Showing 3 changed files with 41 additions and 2 deletions.
diff --git a/packages/next/src/build/index.ts b/packages/next/src/build/index.ts
@@ -2490,8 +2490,29 @@ export default async function build(
                 if (exportRouteMeta.status !== 200) {
                   routeMeta.initialStatus = exportRouteMeta.status
                 }
-                if (Object.keys(exportRouteMeta.headers || {}).length) {
-                  routeMeta.initialHeaders = exportRouteMeta.headers
+                const exportHeaders = exportRouteMeta.headers
+                const headerKeys = Object.keys(exportHeaders || {})
+
+                if (exportHeaders && headerKeys.length) {
+                  routeMeta.initialHeaders = {}
+
+                  // normalize header values as initialHeaders
+                  // must be Record<string, string>
+                  for (const key of headerKeys) {
+                    let value = exportHeaders[key]
+
+                    if (Array.isArray(value)) {
+                      if (key === 'set-cookie') {
+                        value = value.join(',')
+                      } else {
+                        value = value[value.length - 1]
+                      }
+                    }
+
+                    if (typeof value === 'string') {
+                      routeMeta.initialHeaders[key] = value
+                    }
+                  }
                 }
 
                 finalPrerenderRoutes[route] = {

diff --git a/test/e2e/app-dir/app-static/app-static.test.ts b/test/e2e/app-dir/app-static/app-static.test.ts
@@ -510,6 +510,7 @@ createNextDescribe(
           'route-handler/post/route.js',
           'route-handler/revalidate-360-isr/route.js',
           'route-handler/revalidate-360/route.js',
+          'route-handler/static-cookies/route.js',
           'ssg-draft-mode.html',
           'ssg-draft-mode.rsc',
           'ssg-draft-mode/[[...route]]/page.js',
@@ -752,6 +753,15 @@ createNextDescribe(
             initialRevalidateSeconds: 10,
             srcRoute: '/route-handler/revalidate-360-isr',
           },
+          '/route-handler/static-cookies': {
+            dataRoute: null,
+            initialHeaders: {
+              'set-cookie': 'theme=light; Path=/,my_company=ACME; Path=/',
+              'x-next-cache-tags': '/route-handler/static-cookies/route',
+            },
+            initialRevalidateSeconds: false,
+            srcRoute: '/route-handler/static-cookies',
+          },
           '/variable-config-revalidate/revalidate-3': {
             dataRoute: '/variable-config-revalidate/revalidate-3.rsc',
             initialRevalidateSeconds: 3,

diff --git a/test/e2e/app-dir/app-static/app/route-handler/static-cookies/route.js b/test/e2e/app-dir/app-static/app/route-handler/static-cookies/route.js
@@ -0,0 +1,8 @@
+import { NextResponse } from 'next/server'
+
+export function GET() {
+  const res = new NextResponse()
+  res.cookies.set('theme', 'light')
+  res.cookies.set('my_company', 'ACME')
+  return res
+}