Correct query behavior for falsey values to pre 9.5.1 behavior (#16608)

Fixes #16147

packages/next/next-server/lib/router/utils/querystring.ts

@@ -16,15 +16,27 @@ export function searchParamsToUrlQuery(
   return query
 }
 
+function stringifyUrlQueryParam(param: string): string {
+  if (
+    typeof param === 'string' ||
+    (typeof param === 'number' && !isNaN(param)) ||
+    typeof param === 'boolean'
+  ) {
+    return String(param)
+  } else {
+    return ''
+  }
+}
+
 export function urlQueryToSearchParams(
   urlQuery: ParsedUrlQuery
 ): URLSearchParams {
   const result = new URLSearchParams()
   Object.entries(urlQuery).forEach(([key, value]) => {
     if (Array.isArray(value)) {
-      value.forEach((item) => result.append(key, item))
+      value.forEach((item) => result.append(key, stringifyUrlQueryParam(item)))
     } else {
-      result.set(key, value)
+      result.set(key, stringifyUrlQueryParam(value))
     }
   })
   return result

test/integration/build-output/test/index.test.js

@@ -104,7 +104,7 @@ describe('Build Output', () => {
       expect(parseFloat(err404FirstLoad) - 63.6).toBeLessThanOrEqual(0)
       expect(err404FirstLoad.endsWith('kB')).toBe(true)
 
-      expect(parseFloat(sharedByAll) - 60.1).toBeLessThanOrEqual(0)
+      expect(parseFloat(sharedByAll) - 60.2).toBeLessThanOrEqual(0)
       expect(sharedByAll.endsWith('kB')).toBe(true)
 
       if (_appSize.endsWith('kB')) {

test/integration/client-navigation/pages/nav/query-params.js

@@ -0,0 +1,43 @@
+import { useRouter } from 'next/router'
+
+export default function Page() {
+  const router = useRouter()
+  return (
+    <>
+      <button
+        id="click-me"
+        onClick={() =>
+          router.push({
+            pathname: '/query',
+            query: {
+              param1: '',
+              param2: undefined,
+              param3: null,
+              param4: 0,
+              param5: false,
+              param6: [],
+              param7: {},
+              param8: NaN,
+              param9: new Date(1234),
+              param10: /hello/,
+              param11: [
+                '',
+                undefined,
+                null,
+                0,
+                false,
+                [],
+                {},
+                NaN,
+                new Date(1234),
+                /hello/,
+              ],
+            },
+          })
+        }
+      >
+        Click me
+      </button>
+    </>
+  )
+}

test/integration/client-navigation/pages/query.js

@@ -0,0 +1,6 @@
+import { useRouter } from 'next/router'
+
+export default function Page() {
+  const router = useRouter()
+  return <pre id="query-value">{JSON.stringify(router.query, null, 2)}</pre>
+}

test/integration/client-navigation/test/index.test.js

@@ -801,6 +801,26 @@ describe('Client Navigation', () => {
 
       await browser.close()
     })
+
+    it('should handle undefined in router.push', async () => {
+      const browser = await webdriver(context.appPort, '/nav/query-params')
+      await browser.elementByCss('#click-me').click()
+      const query = JSON.parse(
+        await browser.waitForElementByCss('#query-value').text()
+      )
+      expect(query).toEqual({
+        param1: '',
+        param2: '',
+        param3: '',
+        param4: '0',
+        param5: 'false',
+        param7: '',
+        param8: '',
+        param9: '',
+        param10: '',
+        param11: ['', '', '', '0', 'false', '', '', '', '', ''],
+      })
+    })
   })
 
   describe('with querystring relative urls', () => {

test/integration/size-limit/test/index.test.js

@@ -100,7 +100,7 @@ describe('Production response size', () => {
     )
 
     // These numbers are without gzip compression!
-    const delta = responseSizesBytes - 169 * 1024
+    const delta = responseSizesBytes - 170 * 1024
     expect(delta).toBeLessThanOrEqual(1024) // don't increase size more than 1kb
     expect(delta).toBeGreaterThanOrEqual(-1024) // don't decrease size more than 1kb without updating target
   })