Add support for notFound in getServerSideProps (#18241)

This is a follow-up to https://github.com/vercel/next.js/pull/17755 which adds support for returning `notFound` to `getServerSideProps` also

packages/next/build/webpack/loaders/next-serverless-loader.ts

@@ -772,7 +772,7 @@ const nextServerlessLoader: loader.Loader = function () {
 
         if (!renderMode) {
           if (_nextData || getStaticProps || getServerSideProps) {
-            if (renderOpts.ssgNotFound) {
+            if (renderOpts.isNotFound) {
               res.statusCode = 404
 
               const NotFoundComponent = ${

packages/next/export/worker.ts

@@ -263,7 +263,7 @@ export default async function exportPage({
         html = (result as any).html
       }
 
-      if (!html && !(curRenderOpts as any).ssgNotFound) {
+      if (!html && !(curRenderOpts as any).isNotFound) {
         throw new Error(`Failed to render serverless page`)
       }
     } else {
@@ -318,7 +318,7 @@ export default async function exportPage({
         html = await renderMethod(req, res, page, query, curRenderOpts)
       }
     }
-    results.ssgNotFound = (curRenderOpts as any).ssgNotFound
+    results.ssgNotFound = (curRenderOpts as any).isNotFound
 
     const validateAmp = async (
       rawAmpHtml: string,

packages/next/next-server/server/next-server.ts

@@ -1351,7 +1351,7 @@ export default class Server {
           html = renderResult.html
           pageData = renderResult.renderOpts.pageData
           sprRevalidate = renderResult.renderOpts.revalidate
-          isNotFound = renderResult.renderOpts.ssgNotFound
+          isNotFound = renderResult.renderOpts.isNotFound
         } else {
           const origQuery = parseUrl(req.url || '', true).query
           const resolvedUrl = formatUrl({
@@ -1393,7 +1393,7 @@ export default class Server {
           // TODO: change this to a different passing mechanism
           pageData = (renderOpts as any).pageData
           sprRevalidate = (renderOpts as any).revalidate
-          isNotFound = (renderOpts as any).ssgNotFound
+          isNotFound = (renderOpts as any).isNotFound
         }
 
         return { html, pageData, sprRevalidate, isNotFound }

packages/next/next-server/server/render.tsx

@@ -643,7 +643,7 @@ export async function renderToHTML(
           )
         }
 
-        ;(renderOpts as any).ssgNotFound = true
+        ;(renderOpts as any).isNotFound = true
         ;(renderOpts as any).revalidate = false
         return null
       }
@@ -753,21 +753,35 @@ export async function renderToHTML(
       }
 
       const invalidKeys = Object.keys(data).filter(
-        (key) => key !== 'props' && key !== 'unstable_redirect'
+        (key) =>
+          key !== 'props' &&
+          key !== 'unstable_redirect' &&
+          key !== 'unstable_notFound'
       )
 
       if (invalidKeys.length) {
         throw new Error(invalidKeysMsg('getServerSideProps', invalidKeys))
       }
 
+      if ('unstable_notFound' in data) {
+        if (pathname === '/404') {
+          throw new Error(
+            `The /404 page can not return unstable_notFound in "getStaticProps", please remove it to continue!`
+          )
+        }
+
+        ;(renderOpts as any).isNotFound = true
+        return null
+      }
+
       if (
-        data.unstable_redirect &&
+        'unstable_redirect' in data &&
         typeof data.unstable_redirect === 'object'
       ) {
         checkRedirectValues(data.unstable_redirect, req)
 
         if (isDataReq) {
-          data.props = {
+          ;(data as any).props = {
             __N_REDIRECT: data.unstable_redirect.destination,
           }
         } else {
@@ -778,7 +792,11 @@ export async function renderToHTML(
 
       if (
         (dev || isBuildTimeSSG) &&
-        !isSerializableProps(pathname, 'getServerSideProps', data.props)
+        !isSerializableProps(
+          pathname,
+          'getServerSideProps',
+          (data as any).props
+        )
       ) {
         // this fn should throw an error instead of ever returning `false`
         throw new Error(
@@ -786,7 +804,7 @@ export async function renderToHTML(
         )
       }
 
-      props.pageProps = Object.assign({}, props.pageProps, data.props)
+      props.pageProps = Object.assign({}, props.pageProps, (data as any).props)
       ;(renderOpts as any).pageData = props
     }
   } catch (dataFetchError) {

packages/next/types/index.d.ts

@@ -132,10 +132,16 @@ export type GetServerSidePropsContext<
   locales?: string[]
 }
 
-export type GetServerSidePropsResult<P> = {
-  props?: P
-  unstable_redirect?: Redirect
-}
+export type GetServerSidePropsResult<P> =
+  | {
+      props: P
+    }
+  | {
+      unstable_redirect: Redirect
+    }
+  | {
+      unstable_notFound: true
+    }
 
 export type GetServerSideProps<
   P extends { [key: string]: any } = { [key: string]: any },

test/integration/getserversideprops/pages/not-found/[slug].js

+import Link from 'next/link'
+import { useRouter } from 'next/router'
+
+export default function Page(props) {
+  const router = useRouter()
+
+  return (
+    <>
+      <p id="gssp">gssp page</p>
+      <p id="props">{JSON.stringify(props)}</p>
+      <p id="router-query">{JSON.stringify(router.query)}</p>
+      <p id="router-pathname">{router.pathname}</p>
+      <p id="router-as-path">{router.asPath}</p>
+      <Link href="/">
+        <a id="to-index">to /</a>
+      </Link>
+      <br />
+    </>
+  )
+}
+
+export const getServerSideProps = ({ query }) => {
+  if (query.hiding) {
+    return {
+      unstable_notFound: true,
+    }
+  }
+
+  return {
+    props: {
+      hello: 'world',
+    },
+  }
+}

test/integration/getserversideprops/pages/not-found/index.js

+import Link from 'next/link'
+import { useRouter } from 'next/router'
+
+export default function Page(props) {
+  const router = useRouter()
+
+  return (
+    <>
+      <p id="gssp">gssp page</p>
+      <p id="props">{JSON.stringify(props)}</p>
+      <p id="router-query">{JSON.stringify(router.query)}</p>
+      <p id="router-pathname">{router.pathname}</p>
+      <p id="router-as-path">{router.asPath}</p>
+      <Link href="/">
+        <a id="to-index">to /</a>
+      </Link>
+      <br />
+    </>
+  )
+}
+
+export const getServerSideProps = ({ query }) => {
+  if (query.hiding) {
+    return {
+      unstable_notFound: true,
+    }
+  }
+
+  return {
+    props: {
+      hello: 'world',
+    },
+  }
+}

test/integration/getserversideprops/test/index.test.js

@@ -118,6 +118,24 @@ const expectedManifestRoutes = () => [
     ),
     page: '/non-json',
   },
+  {
+    dataRouteRegex: `^\\/_next\\/data\\/${escapeRegex(
+      buildId
+    )}\\/not-found.json$`,
+    page: '/not-found',
+  },
+  {
+    dataRouteRegex: `^\\/_next\\/data\\/${escapeRegex(
+      buildId
+    )}\\/not\\-found\\/([^\\/]+?)\\.json$`,
+    namedDataRouteRegex: `^/_next/data/${escapeRegex(
+      buildId
+    )}/not\\-found/(?<slug>[^/]+?)\\.json$`,
+    page: '/not-found/[slug]',
+    routeKeys: {
+      slug: 'slug',
+    },
+  },
   {
     dataRouteRegex: normalizeRegEx(
       `^\\/_next\\/data\\/${escapeRegex(buildId)}\\/refresh.json$`
@@ -235,6 +253,50 @@ const navigateTest = (dev = false) => {
 const runTests = (dev = false) => {
   navigateTest(dev)
 
+  it('should render 404 correctly when notFound is returned (non-dynamic)', async () => {
+    const res = await fetchViaHTTP(appPort, '/not-found', { hiding: true })
+
+    expect(res.status).toBe(404)
+    expect(await res.text()).toContain('This page could not be found')
+  })
+
+  it('should render 404 correctly when notFound is returned client-transition (non-dynamic)', async () => {
+    const browser = await webdriver(appPort, '/')
+    await browser.eval(`(function() {
+      window.beforeNav = 1
+      window.next.router.push('/not-found?hiding=true')
+    })()`)
+
+    await browser.waitForElementByCss('h1')
+    expect(await browser.elementByCss('html').text()).toContain(
+      'This page could not be found'
+    )
+    expect(await browser.eval('window.beforeNav')).toBe(null)
+  })
+
+  it('should render 404 correctly when notFound is returned (dynamic)', async () => {
+    const res = await fetchViaHTTP(appPort, '/not-found/first', {
+      hiding: true,
+    })
+
+    expect(res.status).toBe(404)
+    expect(await res.text()).toContain('This page could not be found')
+  })
+
+  it('should render 404 correctly when notFound is returned client-transition (dynamic)', async () => {
+    const browser = await webdriver(appPort, '/')
+    await browser.eval(`(function() {
+      window.beforeNav = 1
+      window.next.router.push('/not-found/first?hiding=true')
+    })()`)
+
+    await browser.waitForElementByCss('h1')
+    expect(await browser.elementByCss('html').text()).toContain(
+      'This page could not be found'
+    )
+    expect(await browser.eval('window.beforeNav')).toBe(null)
+  })
+
   it('should SSR normal page correctly', async () => {
     const html = await renderViaHTTP(appPort, '/')
     expect(html).toMatch(/hello.*?world/)