fix: override headers within req.rewrite() (#2189)

* fix: adding headers fix

* chore: remove skip

Author: taty2010

cypress/e2e/middleware/enhanced.cy.ts

@@ -13,6 +13,12 @@ describe('Enhanced middleware', () => {
     })
   })
 
+  it('passes in headers within request.rewrite()', () => {
+    cy.request('/request-rewrite').then((response) => {
+      expect(response.headers).to.have.property('x-rewrite-test', 'hello')
+    })
+  })
+
   it('rewrites the response body using request.next()', () => {
     cy.visit('/static')
     cy.get('#message').contains('This was static (& escaping test &) but has been transformed in')

demos/middleware/middleware.ts

@@ -41,7 +41,13 @@ export async function middleware(req: NextRequest) {
   // skipMiddlewareUrlNormalize next config option is used so we have to try to match both html path and data blob path
   if (pathname.startsWith('/request-rewrite') || pathname.endsWith('/request-rewrite.json')) {
     // request.rewrite() should return the MiddlewareResponse object instead of the Response object.
-    const res = await request.rewrite('/static-rewrite')
+    const res = await request.rewrite('/static-rewrite',
+    {
+      headers: {
+        'x-rewrite-test': 'hello',
+        'x-rewrite-test-2': 'hello-2'
+      }
+    })
     const message = `This was static (& escaping test &) but has been transformed in ${req.geo?.city}`
 
     // Transform the response HTML and props

packages/next/src/middleware/response.ts

@@ -11,7 +11,6 @@ export class MiddlewareResponse extends NextResponse {
   private readonly dataTransforms: NextDataTransform[]
   private readonly elementHandlers: Array<[selector: string, handlers: ElementHandlers]>
 
-  // eslint-disable-next-line @typescript-eslint/no-unused-vars
   constructor(public originResponse: Response, init?: ResponseInit) {
     // we need to propagate the set-cookie header, so response.cookies.get works correctly
     const initHeaders = new Headers()
@@ -23,6 +22,12 @@ export class MiddlewareResponse extends NextResponse {
       headers: initHeaders,
     })
 
+    if (init?.headers) {
+      Object.entries(init.headers).forEach(([key, value]) => {
+        this.headers.set(key, value)
+      })
+    }
+
     // These are private in Node when compiling, but we access them in Deno at runtime
     Object.defineProperty(this, 'dataTransforms', {
       value: [],