[next] Fix _next/data resolving priority for dynamic routes

packages/next/src/server-build.ts

@@ -58,6 +58,7 @@ const CORRECT_MIDDLEWARE_ORDER_VERSION = 'v12.1.7-canary.29';
 const NEXT_DATA_MIDDLEWARE_RESOLVING_VERSION = 'v12.1.7-canary.33';
 const EMPTY_ALLOW_QUERY_FOR_PRERENDERED_VERSION = 'v12.2.0';
 const CORRECTED_MANIFESTS_VERSION = 'v12.2.0';
+const NON_NESTED_MIDDLEWARE_VERSION = 'v12.1.7-canary.9';
 
 export async function serverBuild({
   dynamicPages,
@@ -151,6 +152,10 @@ export async function serverBuild({
     nextVersion,
     CORRECTED_MANIFESTS_VERSION
   );
+  const isNonNestedMiddleware = semver.gte(
+    nextVersion,
+    NON_NESTED_MIDDLEWARE_VERSION
+  );
   let hasStatic500 = !!staticPages[path.join(entryDirectory, '500')];
 
   if (lambdaPageKeys.length === 0) {
@@ -1054,6 +1059,23 @@ export async function serverBuild({
     });
   }
 
+  // We stopped duplicating matchers for _next/data routes when we added
+  // x-nextjs-data header resolving but we should still resolve middleware
+  // when the header isn't present so we augment the source to include that.
+  // We don't apply this modification for nested middleware > 1 staticRoute
+  if (isNonNestedMiddleware) {
+    middleware.staticRoutes.forEach(route => {
+      if (!route.src?.match(/_next[\\/]{1,}data/)) {
+        route.src =
+          `^(\\/_next\\/data\\/${escapedBuildId})?(` +
+          route.src
+            ?.replace(/\|\^/g, '|')
+            .replace(/\$$/, ')$')
+            .replace(/\$/g, '(\\.json)?$');
+      }
+    });
+  }
+
   return {
     wildcard: wildcardConfig,
     images:
@@ -1363,7 +1385,30 @@ export async function serverBuild({
       ...denormalizeNextDataRoute(),
 
       // /_next/data routes for getServerProps/getStaticProps pages
-      ...dataRoutes,
+      ...(isNextDataServerResolving
+        ? // when resolving data routes for middleware we need to include
+          // all dynamic routes including non-SSG/SSP so that the priority
+          // is correct
+          dynamicRoutes
+            .map(route => {
+              route = Object.assign({}, route);
+              route.src = path.posix.join(
+                '^/',
+                entryDirectory,
+                '_next/data/',
+                escapedBuildId,
+                route.src.replace(/(^\^|\$$)/g, '') + '.json$'
+              );
+
+              const { pathname } = new URL(route.dest || '/', 'http://n');
+
+              if (prerenders[path.join('./', pathname)]) {
+                route.dest = `/_next/data/${buildId}${pathname}.json`;
+              }
+              return route;
+            })
+            .filter(Boolean)
+        : dataRoutes),
 
       ...(!isNextDataServerResolving
         ? [
@@ -1395,6 +1440,7 @@ export async function serverBuild({
                 'x-nextjs-matched-path': '/$1',
               },
               continue: true,
+              override: true,
             },
             // add a catch-all data route so we don't 404 when getting
             // middleware effects

packages/next/test/fixtures/00-middleware/middleware.js

@@ -2,6 +2,16 @@ import { NextResponse } from 'next/server';
 
 const ALLOWED = ['allowed'];
 
+export const config = {
+  matcher: [
+    '/dynamic/:path*',
+    '/_sites/:path*',
+    '/:teamId/:slug',
+    '/:path*',
+    '/',
+  ],
+};
+
 export function middleware(request) {
   const url = request.nextUrl;
   const pathname = url.pathname;
@@ -12,7 +22,7 @@ export function middleware(request) {
 
   if (url.pathname === '/redirect-me') {
     url.pathname = '/from-middleware';
-    return NextResponse.redirect(url);
+    return NextResponse.redirect(url, 307);
   }
 
   if (url.pathname === '/next') {

packages/next/test/fixtures/00-middleware/pages/[teamId]/[slug].js

@@ -0,0 +1,3 @@
+export default function Page() {
+  return <p>/[teamId]/[slug]</p>;
+}

packages/next/test/fixtures/00-middleware/pages/dynamic/static.js

@@ -0,0 +1,3 @@
+export default function Index() {
+  return <p className="title">static route</p>;
+}

packages/next/test/fixtures/00-middleware/vercel.json

@@ -1,7 +1,42 @@
 {
   "version": 2,
-  "builds": [{ "src": "package.json", "use": "@vercel/next" }],
+  "builds": [
+    {
+      "src": "package.json",
+      "use": "@vercel/next"
+    }
+  ],
   "probes": [
+    {
+      "path": "/_next/data/testing-build-id/dynamic/static.json",
+      "status": 200,
+      "headers": {
+        "x-nextjs-data": 1
+      },
+      "responseHeaders": {
+        "x-matched-path": "/dynamic/static"
+      }
+    },
+    {
+      "path": "/_next/data/testing-build-id/team-1/slug-1.json",
+      "status": 200,
+      "headers": {
+        "x-nextjs-data": 1
+      },
+      "responseHeaders": {
+        "x-matched-path": "/[teamId]/[slug]"
+      }
+    },
+    {
+      "path": "/_next/data/testing-build-id/dynamic/id-1.json",
+      "status": 200,
+      "headers": {
+        "x-nextjs-data": 1
+      },
+      "responseHeaders": {
+        "x-matched-path": "/dynamic/[id]"
+      }
+    },
     {
       "path": "/_next/data/testing-build-id/rewrite-to-site.json",
       "status": 200,
@@ -58,9 +93,28 @@
         "x-nextjs-data": "1"
       },
       "responseHeaders": {
-        "x-nextjs-matched-path": "/dynamic/first"
+        "x-matched-path": "/dynamic/[id]"
       },
       "mustContain": "{}"
+    },
+    {
+      "path": "/_next/data/testing-build-id/redirect-me.json",
+      "status": 307,
+      "fetchOptions": {
+        "redirect": "manual"
+      },
+      "responseHeaders": {
+        "Location": "/from-middleware/"
+      }
+    },
+    {
+      "path": "/_next/data/testing-build-id/_sites/subdomain-1.json",
+      "status": 200,
+      "fetchOptions": {
+        "redirect": "manual"
+      },
+      "mustNotContain": "<html>",
+      "mustContain": "\"site\":\"subdomain-1\""
     }
   ]
 }

packages/next/test/integration/middleware.test.ts

@@ -47,6 +47,9 @@ describe('Middleware simple project', () => {
     expect(redirectIndex).toBeLessThan(beforeFilesIndex);
     expect(middlewareIndex).toBeLessThan(beforeFilesIndex);
     expect(middlewareIndex).toBeLessThan(handleFileSystemIndex);
+    expect(ctx.buildResult.routes[middlewareIndex].src).toMatch(
+      /_next[\\/]{1,}data/
+    );
   });
 
   it('generates deterministic code', async () => {