From b818b5481d79beb5b73c9b7f9e3e6eb87e86cc9c Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Thu, 13 Aug 2020 23:21:46 -0500
Subject: [PATCH 1/2] Update rewrite params query updating

---
 .../webpack/loaders/next-serverless-loader.ts |  2 +-
 .../lib/router/utils/prepare-destination.ts   | 30 +++++++++++++------
 .../custom-routes/test/index.test.js          |  8 +++--
 3 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/packages/next/build/webpack/loaders/next-serverless-loader.ts b/packages/next/build/webpack/loaders/next-serverless-loader.ts
index 7ea31a91aa6ca..5adf4f07dad03 100644
--- a/packages/next/build/webpack/loaders/next-serverless-loader.ts
+++ b/packages/next/build/webpack/loaders/next-serverless-loader.ts
@@ -163,7 +163,7 @@ const nextServerlessLoader: loader.Loader = function () {
             "${basePath}"
           )
 
-          Object.assign(parsedUrl.query, parsedDestination.query, params)
+          Object.assign(parsedUrl.query, parsedDestination.query)
           delete parsedDestination.query
 
           Object.assign(parsedUrl, parsedDestination)
diff --git a/packages/next/next-server/lib/router/utils/prepare-destination.ts b/packages/next/next-server/lib/router/utils/prepare-destination.ts
index f4cc6bf06b0d9..1e297a7fca89e 100644
--- a/packages/next/next-server/lib/router/utils/prepare-destination.ts
+++ b/packages/next/next-server/lib/router/utils/prepare-destination.ts
@@ -1,7 +1,7 @@
 import { ParsedUrlQuery } from 'querystring'
 import { searchParamsToUrlQuery } from './querystring'
 import { parseRelativeUrl } from './parse-relative-url'
-import { compile as compilePathToRegex } from 'next/dist/compiled/path-to-regexp'
+import * as pathToRegexp from 'next/dist/compiled/path-to-regexp'
 
 type Params = { [param: string]: any }
 
@@ -49,9 +49,16 @@ export default function prepareDestination(
     parsedDestination.searchParams
   )
   const destQuery = parsedDestination.query
+  const destPath = `${parsedDestination.pathname!}${
+    parsedDestination.hash || ''
+  }`
+  const destPathParamKeys: pathToRegexp.Key[] = []
+  pathToRegexp.pathToRegexp(destPath, destPathParamKeys)
 
-  let destinationCompiler = compilePathToRegex(
-    `${parsedDestination.pathname!}${parsedDestination.hash || ''}`,
+  const destPathParams = destPathParamKeys.map((key) => key.name)
+
+  let destinationCompiler = pathToRegexp.compile(
+    destPath,
     // we don't validate while compiling the destination since we should
     // have already validated before we got to this point and validating
     // breaks compiling destinations with named pattern params from the source
@@ -69,18 +76,23 @@ export default function prepareDestination(
       // the value needs to start with a forward-slash to be compiled
       // correctly
       value = `/${value}`
-      const queryCompiler = compilePathToRegex(value, { validate: false })
+      const queryCompiler = pathToRegexp.compile(value, { validate: false })
       value = queryCompiler(params).substr(1)
     }
     destQuery[key] = value
   }
 
   // add path params to query if it's not a redirect and not
-  // already defined in destination query
-  if (appendParamsToQuery) {
-    for (const [name, value] of Object.entries(params)) {
-      if (!(name in destQuery)) {
-        destQuery[name] = value
+  // already defined in destination query or path
+  const paramKeys = Object.keys(params)
+
+  if (
+    appendParamsToQuery &&
+    !paramKeys.some((key) => destPathParams.includes(key))
+  ) {
+    for (const key of paramKeys) {
+      if (!(key in destQuery)) {
+        destQuery[key] = params[key]
       }
     }
   }
diff --git a/test/integration/custom-routes/test/index.test.js b/test/integration/custom-routes/test/index.test.js
index 2128a9abd4a19..d3acb92fa4d41 100644
--- a/test/integration/custom-routes/test/index.test.js
+++ b/test/integration/custom-routes/test/index.test.js
@@ -173,6 +173,12 @@ const runTests = (isDev = false) => {
     expect(html).toMatch(/Hello/)
   })
 
+  it('should not append params when one is used in destination path', async () => {
+    const html = await renderViaHTTP(appPort, '/test/with-params?a=b')
+    const $ = cheerio.load(html)
+    expect(JSON.parse($('p').text())).toEqual({ a: 'b' })
+  })
+
   it('should double redirect successfully', async () => {
     const html = await renderViaHTTP(appPort, '/docs/github')
     expect(html).toMatch(/hi there/)
@@ -397,7 +403,6 @@ const runTests = (isDev = false) => {
       {
         pathname: '/first',
         query: {
-          path: 'first',
           keep: 'me',
           and: 'me',
         },
@@ -1164,7 +1169,6 @@ describe('Custom routes', () => {
       expect(data).toEqual({
         query: {
           slug: 'first',
-          name: 'first',
           hello: 'first',
         },
       })

From 021febfbde34c9ae3e0462bd2dbeb5c141795178 Mon Sep 17 00:00:00 2001
From: JJ Kasper <jj@jjsweb.site>
Date: Fri, 14 Aug 2020 10:26:58 -0500
Subject: [PATCH 2/2] Update prerender test

---
 test/integration/prerender/test/index.test.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/test/integration/prerender/test/index.test.js b/test/integration/prerender/test/index.test.js
index 4a79ded6d4a27..f8e6b6810d30f 100644
--- a/test/integration/prerender/test/index.test.js
+++ b/test/integration/prerender/test/index.test.js
@@ -810,7 +810,6 @@ const runTests = (dev = false, isEmulatedServerless = false) => {
         post: `post-${item}`,
       })
       expect(JSON.parse(await browser.elementByCss('#query').text())).toEqual({
-        item: item + '',
         post: `post-${item}`,
       })
     })