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Draft Mode

Static rendering is useful when your pages fetch data from a headless CMS. However, it’s not ideal when you’re writing a draft on your headless CMS and want to view the draft immediately on your page. You’d want Next.js to render these pages at request time instead of build time and fetch the draft content instead of the published content. You’d want Next.js to switch to dynamic rendering only for this specific case.

Next.js has a feature called Draft Mode which solves this problem. Here are instructions on how to use it.

Step 1: Create and access the Route Handler​

First, create a Route Handler. It can have any name - e.g. app/api/draft/route.ts

Then, import draftMode from next/headers and call the enable() method.

// route handler enabling draft mode
import { draftMode } from 'next/headers'

export async function GET(request: Request) {
  draftMode().enable()
  return new Response('Draft mode is enabled')
}
// route handler enabling draft mode
import { draftMode } from 'next/headers'

export async function GET(request) {
  draftMode().enable()
  return new Response('Draft mode is enabled')
}

This will set a cookie to enable draft mode. Subsequent requests containing this cookie will trigger Draft Mode changing the behavior for statically generated pages (more on this later).

You can test this manually by visiting /api/draft and looking at your browser’s developer tools. Notice the Set-Cookie response header with a cookie named __prerender_bypass.

Securely accessing it from your Headless CMS​

In practice, you’d want to call this Route Handler securely from your headless CMS. The specific steps will vary depending on which headless CMS you’re using, but here are some common steps you could take.

These steps assume that the headless CMS you’re using supports setting custom draft URLs. If it doesn’t, you can still use this method to secure your draft URLs, but you’ll need to construct and access the draft URL manually.

First, you should create a secret token string using a token generator of your choice. This secret will only be known by your Next.js app and your headless CMS. This secret prevents people who don’t have access to your CMS from accessing draft URLs.

Second, if your headless CMS supports setting custom draft URLs, specify the following as the draft URL. This assumes that your Route Handler is located at app/api/draft/route.ts

https://<your-site>/api/draft?secret=<token>&slug=<path>
  • <your-site> should be your deployment domain.
  • <token> should be replaced with the secret token you generated.
  • <path> should be the path for the page that you want to view. If you want to view /posts/foo, then you should use &slug=/posts/foo.

Your headless CMS might allow you to include a variable in the draft URL so that <path> can be set dynamically based on the CMS’s data like so: &slug=/posts/{entry.fields.slug}

Finally, in the Route Handler:

  • Check that the secret matches and that the slug parameter exists (if not, the request should fail).
  • Call draftMode.enable() to set the cookie.
  • Then redirect the browser to the path specified by slug.
// route handler with secret and slug
import { draftMode } from 'next/headers'
import { redirect } from 'next/navigation'

export async function GET(request: Request) {
  // Parse query string parameters
  const { searchParams } = new URL(request.url)
  const secret = searchParams.get('secret')
  const slug = searchParams.get('slug')

  // Check the secret and next parameters
  // This secret should only be known to this route handler and the CMS
  if (secret !== 'MY_SECRET_TOKEN' || !slug) {
    return new Response('Invalid token', { status: 401 })
  }

  // Fetch the headless CMS to check if the provided `slug` exists
  // getPostBySlug would implement the required fetching logic to the headless CMS
  const post = await getPostBySlug(slug)

  // If the slug doesn't exist prevent draft mode from being enabled
  if (!post) {
    return new Response('Invalid slug', { status: 401 })
  }

  // Enable Draft Mode by setting the cookie
  draftMode().enable()

  // Redirect to the path from the fetched post
  // We don't redirect to searchParams.slug as that might lead to open redirect vulnerabilities
  redirect(post.slug)
}
// route handler with secret and slug
import { draftMode } from 'next/headers'
import { redirect } from 'next/navigation'

export async function GET(request) {
  // Parse query string parameters
  const { searchParams } = new URL(request.url)
  const secret = searchParams.get('secret')
  const slug = searchParams.get('slug')

  // Check the secret and next parameters
  // This secret should only be known to this route handler and the CMS
  if (secret !== 'MY_SECRET_TOKEN' || !slug) {
    return new Response('Invalid token', { status: 401 })
  }

  // Fetch the headless CMS to check if the provided `slug` exists
  // getPostBySlug would implement the required fetching logic to the headless CMS
  const post = await getPostBySlug(slug)

  // If the slug doesn't exist prevent draft mode from being enabled
  if (!post) {
    return new Response('Invalid slug', { status: 401 })
  }

  // Enable Draft Mode by setting the cookie
  draftMode().enable()

  // Redirect to the path from the fetched post
  // We don't redirect to searchParams.slug as that might lead to open redirect vulnerabilities
  redirect(post.slug)
}

If it succeeds, then the browser will be redirected to the path you want to view with the draft mode cookie.

Step 2: Update page​

The next step is to update your page to check the value of draftMode().isEnabled.

If you request a page which has the cookie set, then data will be fetched at request time (instead of at build time).

Furthermore, the value of isEnabled will be true.

// page that fetches data
import { draftMode } from 'next/headers'

async function getData() {
  const { isEnabled } = draftMode()

  const url = isEnabled
    ? 'https://draft.example.com'
    : 'https://production.example.com'

  const res = await fetch(url)

  return res.json()
}

export default async function Page() {
  const { title, desc } = await getData()

  return (
    <main>
      <h1>{title}</h1>
      <p>{desc}</p>
    </main>
  )
}
// page that fetches data
import { draftMode } from 'next/headers'

async function getData() {
  const { isEnabled } = draftMode()

  const url = isEnabled
    ? 'https://draft.example.com'
    : 'https://production.example.com'

  const res = await fetch(url)

  return res.json()
}

export default async function Page() {
  const { title, desc } = await getData()

  return (
    <main>
      <h1>{title}</h1>
      <p>{desc}</p>
    </main>
  )
}

That's it! If you access the draft Route Handler (with secret and slug) from your headless CMS or manually, you should now be able to see the draft content. And if you update your draft without publishing, you should be able to view the draft.

Set this as the draft URL on your headless CMS or access manually, and you should be able to see the draft.

https://<your-site>/api/draft?secret=<token>&slug=<path>

More Details​

By default, the Draft Mode session ends when the browser is closed.

To clear the Draft Mode cookie manually, create a Route Handler that calls draftMode().disable():

import { draftMode } from 'next/headers'

export async function GET(request: Request) {
  draftMode().disable()
  return new Response('Draft mode is disabled')
}
import { draftMode } from 'next/headers'

export async function GET(request) {
  draftMode().disable()
  return new Response('Draft mode is disabled')
}

Then, send a request to /api/disable-draft to invoke the Route Handler. If calling this route using next/link, you must pass prefetch={false} to prevent accidentally deleting the cookie on prefetch.

Unique per next build​

A new bypass cookie value will be generated each time you run next build.

This ensures that the bypass cookie can’t be guessed.

Good to know: To test Draft Mode locally over HTTP, your browser will need to allow third-party cookies and local storage access.