From 6c14a3895f06a268a8f82cf818090ce59a44ef1a Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Mon, 13 Jun 2022 15:09:59 -0500
Subject: [PATCH] Fix rewrite/dynamic interpolation E2E cases

---
 .../loaders/next-serverless-loader/utils.ts   | 10 +++-
 packages/next/server/base-server.ts           | 54 ++++++++++---------
 test/production/required-server-files.test.ts | 17 ++++++
 3 files changed, 54 insertions(+), 27 deletions(-)

diff --git a/packages/next/build/webpack/loaders/next-serverless-loader/utils.ts b/packages/next/build/webpack/loaders/next-serverless-loader/utils.ts
index 2703a90e9d227..dffb65244b408 100644
--- a/packages/next/build/webpack/loaders/next-serverless-loader/utils.ts
+++ b/packages/next/build/webpack/loaders/next-serverless-loader/utils.ts
@@ -340,7 +340,10 @@ export function getUtils({
     }
   }
 
-  function normalizeDynamicRouteParams(params: ParsedUrlQuery) {
+  function normalizeDynamicRouteParams(
+    params: ParsedUrlQuery,
+    ignoreOptional?: boolean
+  ) {
     let hasValidParams = true
     if (!defaultRouteRegex) return { params, hasValidParams: false }
 
@@ -361,7 +364,10 @@ export function getUtils({
           })
         : value?.includes(defaultValue as string)
 
-      if (isDefaultValue || (typeof value === 'undefined' && !isOptional)) {
+      if (
+        isDefaultValue ||
+        (typeof value === 'undefined' && !(isOptional && ignoreOptional))
+      ) {
         hasValidParams = false
       }
 
diff --git a/packages/next/server/base-server.ts b/packages/next/server/base-server.ts
index 373f7b95bfecc..309c4bdcacc17 100644
--- a/packages/next/server/base-server.ts
+++ b/packages/next/server/base-server.ts
@@ -517,27 +517,20 @@ export default abstract class Server<ServerOptions extends Options = Options> {
               parsedUrl.query
             )
 
+            // for prerendered ISR paths we attempt parsing the route
+            // params from the URL directly as route-matches may not
+            // contain the correct values due to the filesystem path
+            // matching before the dynamic route has been matched
             if (
-              !isDynamicRoute(normalizedUrlPath) ||
-              !isDynamicRoute(matchedPath)
+              !paramsResult.hasValidParams &&
+              pageIsDynamic &&
+              !isDynamicRoute(normalizedUrlPath)
             ) {
-              // we favor matching against req.url although if there's a
-              // rewrite and it's SSR we use the x-matched-path instead
-              let matcherRes = utils.dynamicRouteMatcher?.(normalizedUrlPath)
+              let matcherParams = utils.dynamicRouteMatcher?.(normalizedUrlPath)
 
-              if (!matcherRes) {
-                matcherRes = utils.dynamicRouteMatcher?.(matchedPath)
-              }
-              const parsedResult = utils.normalizeDynamicRouteParams(
-                matcherRes || {}
-              )
-
-              if (parsedResult.hasValidParams) {
-                if (paramsResult.hasValidParams) {
-                  Object.assign(paramsResult.params, parsedResult.params)
-                } else {
-                  paramsResult = parsedResult
-                }
+              if (matcherParams) {
+                Object.assign(paramsResult.params, matcherParams)
+                paramsResult.hasValidParams = true
               }
             }
 
@@ -547,9 +540,8 @@ export default abstract class Server<ServerOptions extends Options = Options> {
 
             if (
               req.headers['x-now-route-matches'] &&
-              (!paramsResult.hasValidParams ||
-                (isDynamicRoute(matchedPath) &&
-                  isDynamicRoute(normalizedUrlPath)))
+              isDynamicRoute(matchedPath) &&
+              !paramsResult.hasValidParams
             ) {
               const opts: Record<string, string> = {}
               const routeParams = utils.getParamsFromRouteMatches(
@@ -561,17 +553,29 @@ export default abstract class Server<ServerOptions extends Options = Options> {
               if (opts.locale) {
                 parsedUrl.query.__nextLocale = opts.locale
               }
-              paramsResult = utils.normalizeDynamicRouteParams(routeParams)
+              paramsResult = utils.normalizeDynamicRouteParams(
+                routeParams,
+                true
+              )
 
               if (paramsResult.hasValidParams) {
                 params = paramsResult.params
               }
             }
 
+            // handle the actual dynamic route name being requested
+            if (
+              pageIsDynamic &&
+              utils.defaultRouteMatches &&
+              normalizedUrlPath === srcPathname &&
+              !paramsResult.hasValidParams &&
+              !utils.normalizeDynamicRouteParams({ ...params }, true)
+                .hasValidParams
+            ) {
+              params = utils.defaultRouteMatches
+            }
+
             if (params) {
-              if (!paramsResult.hasValidParams) {
-                params = utils.normalizeDynamicRouteParams(params).params
-              }
               matchedPath = utils.interpolateDynamicPath(srcPathname, params)
               req.url = utils.interpolateDynamicPath(req.url!, params)
             }
diff --git a/test/production/required-server-files.test.ts b/test/production/required-server-files.test.ts
index 3e05971337220..a5fae289e7ceb 100644
--- a/test/production/required-server-files.test.ts
+++ b/test/production/required-server-files.test.ts
@@ -1029,6 +1029,23 @@ describe('should set-up next', () => {
     const html = await res.text()
     const $ = cheerio.load(html)
     expect($('#slug-page').text()).toBe('[slug] page')
+    expect(JSON.parse($('#router').text()).query).toEqual({
+      slug: 'slug-1',
+    })
+
+    const res2 = await fetchViaHTTP(appPort, '/[slug]', undefined, {
+      headers: {
+        'x-matched-path': '/[slug]',
+      },
+      redirect: 'manual',
+    })
+
+    const html2 = await res2.text()
+    const $2 = cheerio.load(html2)
+    expect($2('#slug-page').text()).toBe('[slug] page')
+    expect(JSON.parse($2('#router').text()).query).toEqual({
+      slug: '[slug]',
+    })
   })
 
   it('should have correct asPath on dynamic SSG page correctly', async () => {