Support for SSG preview mode

.gitignore

@@ -39,3 +39,9 @@ jspm_packages
 
 # OS
 .DS_Store
+
+# Local Netlify folder
+.netlify
+
+# Cypress Netlify Site ID
+cypress/fixtures/.netlify/state.json

README.md

@@ -35,7 +35,6 @@
  - [Custom Netlify Redirects](#custom-netlify-redirects)
  - [Custom Netlify Functions](#custom-netlify-functions)
 - [Caveats](#caveats)
- - [Preview Mode](#preview-mode)
  - [Fallbacks for Pages with `getStaticPaths`](#fallbacks-for-pages-with-getstaticpaths)
 - [Credits](#credits)
 - [Showcase](#showcase)
@@ -175,10 +174,6 @@ SSR pages and API endpoints. It is currently not possible to create custom Netli
 
 ## Caveats
 
-### Preview Mode
-
-[Next.js Preview Mode](https://nextjs.org/docs/advanced-features/preview-mode) does not work on pages that are pre-rendered (pages with `getStaticProps`). Netlify currently does not support cookie-based redirects, which are needed for supporting preview mode on pre-rendered pages. Preview mode works correctly on any server-side-rendered pages (pages with `getInitialProps` or `getServerSideProps`). See: [Issue #10](https://github.com/netlify/next-on-netlify/issues/10)
-
 ### Fallbacks for Pages with `getStaticPaths`
 
 [Fallback pages](https://nextjs.org/docs/basic-features/data-fetching#fallback-true) behave differently with `next-on-netlify` than they do with Next.js. On Next.js, when navigating to a path that is not defined in `getStaticPaths`, it first displays the fallback page. Next.js then generates the HTML in the background and caches it for future requests.

cypress/fixtures/pages/api/enterPreviewStatic.js

@@ -0,0 +1,12 @@
+export default async function preview(req, res) {
+ const { query } = req;
+ const { id } = query;
+
+ // Enable Preview Mode by setting the cookies
+ res.setPreviewData({});
+
+ // Redirect to the path from the fetched post
+ // We don't redirect to req.query.slug as that might lead to open redirect vulnerabilities
+ res.writeHead(307, { Location: `/previewTest/static` });
+ res.end();
+}

cypress/fixtures/pages/index.js

@@ -230,6 +230,11 @@ const Index = ({ shows }) => (
  <a>previewTest/222</a>
  </Link>
  </li>
+ <li>
+ <Link href="/previewTest/static">
+ <a>previewTest/static</a>
+ </Link>
+ </li>
  </ul>
 
  <h1>6. Static Pages Stay Static</h1>

cypress/fixtures/pages/previewTest/static.js

@@ -0,0 +1,45 @@
+import Link from "next/link";
+
+const StaticTest = ({ number }) => {
+ return (
+ <div>
+ <p>
+ This page uses getStaticProps() and is SSRed when in preview mode.
+ <br />
+ <br />
+ By default, it shows the TV show by ID (as static HTML).
+ <br />
+ But when in preview mode, it shows person by ID instead (SSRed).
+ </p>
+
+ <hr />
+
+ <h1>Number: {number}</h1>
+
+ <Link href="/">
+ <a>Go back home</a>
+ </Link>
+ </div>
+ );
+};
+
+export const getStaticProps = async ({ preview }) => {
+ let number;
+
+ // In preview mode, use odd number
+ if (preview) {
+ number = 3;
+ }
+ // In normal mode, use even number
+ else {
+ number = 4;
+ }
+
+ return {
+ props: {
+ number,
+ },
+ };
+};
+
+export default StaticTest;

cypress/integration/default_spec.js

@@ -529,12 +529,18 @@ describe("API endpoint", () => {
 });
 
 describe("Preview Mode", () => {
- it("redirects to preview test page", () => {
+ it("redirects to preview test page with dynamic route", () => {
  cy.visit("/api/enterPreview?id=999");
 
  cy.url().should("include", "/previewTest/999");
  });
 
+ it("redirects to static preview test page", () => {
+ cy.visit("/api/enterPreviewStatic");
+
+ cy.url().should("include", "/previewTest/static");
+ });
+
  it("sets cookies on client", () => {
  Cypress.Cookies.debug(true);
  cy.getCookie("__prerender_bypass").should("not.exist");
@@ -546,7 +552,18 @@ describe("Preview Mode", () => {
  cy.getCookie("__next_preview_data").should("not.be", null);
  });
 
- it("renders page in preview mode", () => {
+ it("sets cookies on client with static redirect", () => {
+ Cypress.Cookies.debug(true);
+ cy.getCookie("__prerender_bypass").should("not.exist");
+ cy.getCookie("__next_preview_data").should("not.exist");
+
+ cy.visit("/api/enterPreviewStatic");
+
+ cy.getCookie("__prerender_bypass").should("not.be", null);
+ cy.getCookie("__next_preview_data").should("not.be", null);
+ });
+
+ it("renders serverSideProps page in preview mode", () => {
  cy.visit("/api/enterPreview?id=999");
 
  if (Cypress.env("DEPLOY") === "local") {
@@ -557,7 +574,15 @@ describe("Preview Mode", () => {
  cy.get("p").should("contain", "Sebastian Lacause");
  });
 
- it("can move in and out of preview mode", () => {
+ it("renders staticProps page in preview mode", () => {
+ // cypress local (aka netlify dev) doesn't support cookie-based redirects
+ if (Cypress.env("DEPLOY") !== "local") {
+ cy.visit("/api/enterPreviewStatic");
+ cy.get("h1").should("contain", "Number: 3");
+ }
+ });
+
+ it("can move in and out of preview mode for SSRed page", () => {
  cy.visit("/api/enterPreview?id=999");
 
  if (Cypress.env("DEPLOY") === "local") {
@@ -582,6 +607,45 @@ describe("Preview Mode", () => {
  cy.get("h1").should("contain", "Show #222");
  cy.get("p").should("contain", "Happyland");
  });
+
+ it("can move in and out of preview mode for static page", () => {
+ if (Cypress.env("DEPLOY") !== "local") {
+ cy.visit("/api/enterPreviewStatic");
+ cy.window().then((w) => (w.noReload = true));
+
+ cy.get("h1").should("contain", "Number: 3");
+
+ cy.contains("Go back home").click();
+
+ // Verify that we're still in preview mode
+ cy.contains("previewTest/static").click();
+ cy.get("h1").should("contain", "Number: 3");
+
+ cy.window().should("have.property", "noReload", true);
+
+ // Exit preview mode
+ cy.visit("/api/exitPreview");
+
+ // TO-DO: test if this is the static html?
+ // Verify that we're no longer in preview mode
+ cy.contains("previewTest/static").click();
+ cy.get("h1").should("contain", "Number: 4");
+ }
+ });
+
+ it("hits the prerendered html out of preview mode and netlify function in preview mode", () => {
+ if (Cypress.env("DEPLOY") !== "local") {
+ cy.request("/previewTest/static").then((response) => {
+ expect(response.headers["cache-control"]).to.include("public");
+ });
+
+ cy.visit("/api/enterPreviewStatic");
+
+ cy.request("/previewTest/static").then((response) => {
+ expect(response.headers["cache-control"]).to.include("private");
+ });
+ }
+ });
 });
 
 describe("pre-rendered HTML pages", () => {

lib/helpers/isSourceRouteWithFallback.js

@@ -0,0 +1,11 @@
+const getPrerenderManifest = require("./getPrerenderManifest");
+
+const { dynamicRoutes } = getPrerenderManifest();
+
+const isSourceRouteWithFallback = (srcRoute) => {
+ return Object.entries(dynamicRoutes).some(
+ ([route, { fallback }]) => route === srcRoute && fallback !== false
+ );
+};
+
+module.exports = isSourceRouteWithFallback;

lib/helpers/setupNetlifyFunctionForPage.js

@@ -1,4 +1,4 @@
-const { copySync } = require("fs-extra");
+const { copySync, existsSync } = require("fs-extra");
 const { join } = require("path");
 const {
  NEXT_DIST_DIR,
@@ -14,24 +14,21 @@ const setupNetlifyFunctionForPage = (filePath) => {
  const functionDirectory = join(NETLIFY_FUNCTIONS_PATH, functionName);
 
  // Copy function template
- copySync(
- FUNCTION_TEMPLATE_PATH,
- join(functionDirectory, `${functionName}.js`),
- {
- overwrite: false,
- errorOnExist: true,
- }
+ const functionTemplateCopyPath = join(
+ functionDirectory,
+ `${functionName}.js`
  );
+ copySync(FUNCTION_TEMPLATE_PATH, functionTemplateCopyPath, {
+ overwrite: false,
+ errorOnExist: true,
+ });
 
  // Copy page
- copySync(
- join(NEXT_DIST_DIR, "serverless", filePath),
- join(functionDirectory, "nextJsPage.js"),
- {
- overwrite: false,
- errorOnExist: true,
- }
- );
+ const nextPageCopyPath = join(functionDirectory, "nextJsPage.js");
+ copySync(join(NEXT_DIST_DIR, "serverless", filePath), nextPageCopyPath, {
+ overwrite: false,
+ errorOnExist: true,
+ });
 };
 
 module.exports = setupNetlifyFunctionForPage;

lib/pages/getStaticProps/pages.js

@@ -6,15 +6,16 @@ const pages = [];
 // Get pages using getStaticProps
 const { routes } = getPrerenderManifest();
 
-// Parse pages
+// Parse static pages
 Object.entries(routes).forEach(
- ([route, { dataRoute, initialRevalidateSeconds }]) => {
+ ([route, { dataRoute, initialRevalidateSeconds, srcRoute }]) => {
  // Ignore pages with revalidate, these will need to be SSRed
  if (initialRevalidateSeconds) return;
 
  pages.push({
  route,
  dataRoute,
+ srcRoute,
  });
  }
 );

lib/pages/getStaticProps/redirects.js

@@ -1,7 +1,36 @@
+const { join } = require("path");
+const getFilePathForRoute = require("../../helpers/getFilePathForRoute");
+const getNetlifyFunctionName = require("../../helpers/getNetlifyFunctionName");
 const pages = require("./pages");
 
-// Pages with getStaticProps do not need redirects, unless they are using
-// fallback: true or a revalidation interval. Both are handled by other files.
+// Pages with getStaticProps (without fallback or revalidation) only need
+// redirects for handling preview mode.
 const redirects = [];
 
+pages.forEach(({ route, dataRoute, srcRoute }) => {
+ const relativePath = getFilePathForRoute(srcRoute || route, "js");
+ const filePath = join("pages", relativePath);
+ const functionName = getNetlifyFunctionName(filePath);
+
+ const conditions = ["Cookie=__prerender_bypass,__next_preview_data"];
+ const target = `/.netlify/functions/${functionName}`;
+
+ // Add one redirect for the page, but only when the NextJS
+ // preview mode cookies are present
+ redirects.push({
+ route,
+ target,
+ force: true,
+ conditions,
+ });
+
+ // Add one redirect for the data route, same conditions
+ redirects.push({
+ route: dataRoute,
+ target,
+ force: true,
+ conditions,
+ });
+});
+
 module.exports = redirects;

lib/pages/getStaticProps/setup.js

@@ -1,7 +1,10 @@
+const { join } = require("path");
 const { logTitle, logItem } = require("../../helpers/logger");
 const { NETLIFY_PUBLISH_PATH } = require("../../config");
 const getFilePathForRoute = require("../../helpers/getFilePathForRoute");
+const isSourceRouteWithFallback = require("../../helpers/isSourceRouteWithFallback");
 const setupStaticFileForPage = require("../../helpers/setupStaticFileForPage");
+const setupNetlifyFunctionForPage = require("../../helpers/setupNetlifyFunctionForPage");
 const pages = require("./pages");
 
 // Copy pre-rendered SSG pages
@@ -11,7 +14,11 @@ const setup = () => {
  NETLIFY_PUBLISH_PATH
  );
 
- pages.forEach(({ route, dataRoute }) => {
+ // Keep track of the functions that have been set up, so that we do not set up
+ // a function for the same file path twice
+ const filePathsDone = [];
+
+ pages.forEach(({ route, dataRoute, srcRoute }) => {
  logItem(route);
 
  // Copy pre-rendered HTML page
@@ -21,6 +28,19 @@ const setup = () => {
  // Copy page's JSON data
  const jsonPath = getFilePathForRoute(route, "json");
  setupStaticFileForPage(jsonPath, dataRoute);
+
+ // // Set up the Netlify function (this is ONLY for preview mode)
+ const relativePath = getFilePathForRoute(srcRoute || route, "js");
+ const filePath = join("pages", relativePath);
+
+ // Skip if we have already set up a function for this file
+ // or if the source route has fallback: true
+ if (filePathsDone.includes(filePath) || isSourceRouteWithFallback(srcRoute))
+ return;
+
+ logItem(filePath);
+ setupNetlifyFunctionForPage(filePath);
+ filePathsDone.push(filePath);
  });
 };
 

lib/steps/setupRedirects.js

@@ -45,7 +45,19 @@ const setupRedirects = () => {
  // One route may map to multiple Netlify routes: e.g., catch-all pages
  // require two Netlify routes in the _redirects file
  getNetlifyRoutes(route).map((netlifyRoute) => {
- const redirect = `${netlifyRoute} ${nextRedirect.target} 200`;
+ const {
+ conditions = [],
+ force = false,
+ statusCode = "200",
+ target,
+ } = nextRedirect;
+ const redirectPieces = [
+ netlifyRoute,
+ target,
+ `${statusCode}${force ? "!" : ""}`,
+ conditions.join(" "),
+ ];
+ const redirect = redirectPieces.join(" ").trim();
  logItem(redirect);
  redirects.push(redirect);
  });
@@ -61,6 +73,10 @@ const setupRedirects = () => {
  redirects.splice(rootCatchAllIndex, 0, "/_next/* /_next/:splat 200");
  }
 
+ // Add workaround that was introduced for pre-traffic mesh cookie-based redirects
+ // TO-DO: remove when internal netlify bug is resolved
+ if (nextRedirects.length >= 1) redirects.push("/* /:splat 200");
+
  // Write redirects to _redirects file
  writeFileSync(join(NETLIFY_PUBLISH_PATH, "_redirects"), redirects.join("\n"));
 };