Update to make sure preview mode works with getServerSideProps

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

@@ -905,6 +905,14 @@ export default class Server {
       })
     }
 
+    let previewData: string | false | object | undefined
+    let isPreviewMode = false
+
+    if (isServerProps || isSSG) {
+      previewData = tryGetPreviewData(req, res, this.renderOpts.previewProps)
+      isPreviewMode = previewData !== false
+    }
+
     // non-spr requests should render like normal
     if (!isSSG) {
       // handle serverless
@@ -923,7 +931,7 @@ export default class Server {
             !this.renderOpts.dev
               ? {
                   revalidate: -1,
-                  private: false, // Leave to user-land caching
+                  private: isPreviewMode, // Leave to user-land caching
                 }
               : undefined
           )
@@ -946,25 +954,27 @@ export default class Server {
           !this.renderOpts.dev
             ? {
                 revalidate: -1,
-                private: false, // Leave to user-land caching
+                private: isPreviewMode, // Leave to user-land caching
               }
             : undefined
         )
         return null
       }
 
-      return renderToHTML(req, res, pathname, query, {
+      const html = await renderToHTML(req, res, pathname, query, {
         ...components,
         ...opts,
       })
-    }
 
-    const previewData = tryGetPreviewData(
-      req,
-      res,
-      this.renderOpts.previewProps
-    )
-    const isPreviewMode = previewData !== false
+      if (html && isServerProps && isPreviewMode) {
+        sendPayload(res, html, 'text/html; charset=utf-8', {
+          revalidate: -1,
+          private: isPreviewMode,
+        })
+      }
+
+      return html
+    }
 
     // Compute the SPR cache key
     const urlPathname = parseUrl(req.url || '').pathname!

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

@@ -321,7 +321,7 @@ export async function renderToHTML(
   const isFallback = !!query.__nextFallback
   delete query.__nextFallback
 
-  const isSpr = !!getStaticProps
+  const isSSG = !!getStaticProps
   const defaultAppGetInitialProps =
     App.getInitialProps === (App as any).origGetInitialProps
 
@@ -332,7 +332,7 @@ export async function renderToHTML(
   const isAutoExport =
     !hasPageGetInitialProps &&
     defaultAppGetInitialProps &&
-    !isSpr &&
+    !isSSG &&
     !getServerSideProps
 
   if (
@@ -355,25 +355,25 @@ export async function renderToHTML(
     )
   }
 
-  if (hasPageGetInitialProps && isSpr) {
+  if (hasPageGetInitialProps && isSSG) {
     throw new Error(SSG_GET_INITIAL_PROPS_CONFLICT + ` ${pathname}`)
   }
 
   if (hasPageGetInitialProps && getServerSideProps) {
     throw new Error(SERVER_PROPS_GET_INIT_PROPS_CONFLICT + ` ${pathname}`)
   }
 
-  if (getServerSideProps && isSpr) {
+  if (getServerSideProps && isSSG) {
     throw new Error(SERVER_PROPS_SSG_CONFLICT + ` ${pathname}`)
   }
 
-  if (!!getStaticPaths && !isSpr) {
+  if (!!getStaticPaths && !isSSG) {
     throw new Error(
       `getStaticPaths was added without a getStaticProps in ${pathname}. Without getStaticProps, getStaticPaths does nothing`
     )
   }
 
-  if (isSpr && pageIsDynamic && !getStaticPaths) {
+  if (isSSG && pageIsDynamic && !getStaticPaths) {
     throw new Error(
       `getStaticPaths is required for dynamic SSG pages and is missing for '${pathname}'.` +
         `\nRead more: https://err.sh/next.js/invalid-getstaticpaths-value`
@@ -414,7 +414,7 @@ export async function renderToHTML(
     }
   }
   if (isAutoExport) renderOpts.autoExport = true
-  if (isSpr) renderOpts.nextExport = false
+  if (isSSG) renderOpts.nextExport = false
 
   await Loadable.preloadAll() // Make sure all dynamic imports are loaded
 
@@ -471,12 +471,16 @@ export async function renderToHTML(
       router,
       ctx,
     })
+    let previewData: string | false | object | undefined
 
-    if (isSpr && !isFallback) {
+    if ((isSSG || getServerSideProps) && !isFallback) {
       // Reads of this are cached on the `req` object, so this should resolve
       // instantly. There's no need to pass this data down from a previous
       // invoke, where we'd have to consider server & serverless.
-      const previewData = tryGetPreviewData(req, res, previewProps)
+      previewData = tryGetPreviewData(req, res, previewProps)
+    }
+
+    if (isSSG && !isFallback) {
       const data = await getStaticProps!({
         ...(pageIsDynamic ? { params: query as ParsedUrlQuery } : undefined),
         ...(previewData !== false
@@ -529,33 +533,36 @@ export async function renderToHTML(
       ;(renderOpts as any).revalidate = data.revalidate
       ;(renderOpts as any).pageData = props
     }
+
+    if (getServerSideProps && !isFallback) {
+      const data = await getServerSideProps({
+        req,
+        res,
+        query,
+        ...(pageIsDynamic ? { params: params as ParsedUrlQuery } : undefined),
+        ...(previewData !== false
+          ? { preview: true, previewData: previewData }
+          : undefined),
+      })
+
+      const invalidKeys = Object.keys(data).filter(key => key !== 'props')
+
+      if (invalidKeys.length) {
+        throw new Error(invalidKeysMsg('getServerSideProps', invalidKeys))
+      }
+
+      props.pageProps = data.props
+      ;(renderOpts as any).pageData = props
+    }
   } catch (err) {
     if (!dev || !err) throw err
     ctx.err = err
     renderOpts.err = err
     console.error(err)
   }
 
-  if (getServerSideProps && !isFallback) {
-    const data = await getServerSideProps({
-      req,
-      res,
-      ...(pageIsDynamic ? { params: params as ParsedUrlQuery } : undefined),
-      query,
-    })
-
-    const invalidKeys = Object.keys(data).filter(key => key !== 'props')
-
-    if (invalidKeys.length) {
-      throw new Error(invalidKeysMsg('getServerSideProps', invalidKeys))
-    }
-
-    props.pageProps = data.props
-    ;(renderOpts as any).pageData = props
-  }
-
   if (
-    !isSpr && // we only show this warning for legacy pages
+    !isSSG && // we only show this warning for legacy pages
     !getServerSideProps &&
     process.env.NODE_ENV !== 'production' &&
     Object.keys(props?.pageProps || {}).includes('url')
@@ -577,7 +584,7 @@ export async function renderToHTML(
   }
 
   // the response might be finished on the getInitialProps call
-  if (isResSent(res) && !isSpr) return null
+  if (isResSent(res) && !isSSG) return null
 
   const devFiles = buildManifest.devFiles
   const files = [
@@ -634,7 +641,7 @@ export async function renderToHTML(
     documentCtx
   )
   // the response might be finished on the getInitialProps call
-  if (isResSent(res) && !isSpr) return null
+  if (isResSent(res) && !isSSG) return null
 
   if (!docProps || typeof docProps.html !== 'string') {
     const message = `"${getDisplayName(

packages/next/types/index.d.ts

@@ -83,6 +83,8 @@ export type GetServerSideProps = (context: {
   res: ServerResponse
   params?: ParsedUrlQuery
   query: ParsedUrlQuery
+  preview?: boolean
+  previewData?: any
 }) => Promise<{ [key: string]: any }>
 
 export default next

test/integration/getserversideprops-preview/pages/api/preview.js

@@ -0,0 +1,4 @@
+export default (req, res) => {
+  res.setPreviewData(req.query)
+  res.status(200).end()
+}

test/integration/getserversideprops-preview/pages/api/reset.js

@@ -0,0 +1,4 @@
+export default (req, res) => {
+  res.clearPreviewData()
+  res.status(200).end()
+}

test/integration/getserversideprops-preview/pages/index.js

@@ -0,0 +1,15 @@
+export function getServerSideProps({ preview, previewData }) {
+  return { props: { hasProps: true, preview, previewData } }
+}
+
+export default function({ hasProps, preview, previewData }) {
+  if (!hasProps) {
+    return <pre id="props-pre">Has No Props</pre>
+  }
+
+  return (
+    <pre id="props-pre">
+      {JSON.stringify(preview) + ' and ' + JSON.stringify(previewData)}
+    </pre>
+  )
+}

test/integration/getserversideprops-preview/server.js

@@ -0,0 +1,41 @@
+const http = require('http')
+const url = require('url')
+const fs = require('fs')
+const path = require('path')
+const server = http.createServer((req, res) => {
+  let { pathname } = url.parse(req.url)
+  if (pathname.startsWith('/_next/data')) {
+    pathname = pathname
+      .replace(`/_next/data/${process.env.BUILD_ID}/`, '/')
+      .replace(/\.json$/, '')
+  }
+  console.log('serving', pathname)
+
+  if (pathname === '/favicon.ico') {
+    res.statusCode = 404
+    return res.end()
+  }
+
+  if (pathname.startsWith('/_next/static/')) {
+    res.write(
+      fs.readFileSync(
+        path.join(
+          __dirname,
+          './.next/static/',
+          pathname.slice('/_next/static/'.length)
+        ),
+        'utf8'
+      )
+    )
+    return res.end()
+  } else {
+    const re = require(`./.next/serverless/pages${pathname}`)
+    return typeof re.render === 'function'
+      ? re.render(req, res)
+      : re.default(req, res)
+  }
+})
+
+server.listen(process.env.PORT, () => {
+  console.log('ready on', process.env.PORT)
+})