#Live preview

Hygraph Studio's Live Preview feature allows you to preview content in your frontend before it's published.

#What you can do

• Preview your work in a side-by-side view before it goes live.
• Switch between different screen sizes, such as desktop, mobile, or full width.
• Enhance your preview with the Preview SDK for real-time updates and interactive editing.

#Limitations

• Live Preview is not compatible with native mobile applications.
• Requests count against rate limits and usage of your project.

#Add a preview widget

Live preview - Add to content model

To use live preview, you must first add a preview widget to a model in your schema.

1. Navigate to the Schema builder.

2. Select a model to add the preview widget

3. Click on the Sidebar tab, located at the top of the screen.

4. Select the Preview widget from the right sidebar.

5. Complete the Preview name and the URL template fields.

   Pro Tip

   This is where you can add your own website URL and specify how the preview slug should be constructed from field values in the content entry.

   Click here to learn how to define your own preview URLs.

6. Click Add to save.

You can now use the live preview feature.

#How to define a URL template

The exact way to build a URL template for previews depends on your website's URL structure. You need to have a frontend already set up to be able to configure previews. You can also add localhost URLs so you can preview your work locally before publishing your website.

Typically, you will start with your domain, then a section such as a "blog". Finally, you will use handlebars notation to include a field that is unique to the content you want to preview, to use as an identifier - usually a unique slug or the ID.

The preview URL structure will vary based on your project. For example:https://preview.your-domain.com/blog/{slug} or https://your-domain.com/blog/{slug}?preview=true

The {slug} token is the most important. This will dynamically add the slug of what you are editing to the preview URL.

As soon as you type in the open curly brace in the URL template field, the system will list all the Available fields that you can add to the URL. You can use more than one of the available fields, if needed.

We also recommend adding a secret token to the URL, which only your app and Hygraph will know.

Check out our live preview implementation guides.

#Set up live preview for Variants

With Live Preview, you can preview content from Variants in your frontend before publishing.

Ensure that you've added the live preview widget and set up the preview URL template for your content entry. To configure live preview for your variants, do the following:

1. Navigate to the Schema builder.

2. Select the model for which you've enabled variants.

3. Click the Sidebar tab, and for the Preview widget, select Edit widget.

4. Under Variant preview settings, complete the Preview name and the URL template fields. You can use the following preview URL template options:

   • https://preview.your-domain.com/post/${id}?variant=${variant.id}
   • https://preview.your-domain.com/post/${id}?segment={variant.segments[0].id}
   • https://preview.your-domain.com/post/${id}?segments={variant.segments[*].id}

5. Click Update to save.

#Example URL template for variants

Use the Variant ID, the Segment ID, or multiple Segment IDs to set up the URL template. As a developer, you need to interpret the query parameter, and show the right variant by querying the API. For example:

{variant.segments[*].id} returns a comma separated list of all segments. Commas are encoded as %2C in the URL.

#Use live preview

Follow these steps to preview your content:

1. Navigate to the Content editor and select a content view.
2. Click an existing entry to edit it.
3. Click Open live preview on the right sidebar. The preview will display to the right of the content editing screen.
4. Make changes to the content entry and then click Save & preview.

Our live preview feature will show you a side-by-side content preview in the Hygraph content form:

Live preview

To update the preview after making additional changes, make sure to click Save & preview.

#Switch view

At the top of your preview you will find view switcher options that allow previewing the website for different screen sizes.

Switch view

Simply click on one of the three buttons to select a preview size. The available options are: desktop, mobile, and full width.

#Delete the preview widget

Delete a preview widget

1. Navigate to the Schema builder.
2. Select the model that contains the preview widget that you want to delete.
3. Click on the context menu for the widget, and select Remove.

#Troubleshooting

#CSP or security header issues

Once the preview is set up, the live preview panel may display an error message. If this happens, it could be due to a strict security configuration (Security Header or Content Security Policy) on your website that prevents other websites from embedding it.

To resolve this, contact your development or security team to adjust your website's security configuration.

To fix this issue, we need to verify what's causing it. Follow these steps:

1. Navigate to the Network tab in your browser console.

2. Search for the page you are trying to see.

3. Under the Headers subtab, click on the Response Headers.

4. Determine whether the security configuration matches one of the options below:

   • If the X-Frame-Options header is set, remove it from your application.

   OR

   • If the Content-Security-Policy header doesn't include the Hygraph domain, you need to add it. It should look similar to this: frame-ancestors 'self' https://*.hygraph.com.

#Stale data

If you're dealing with stale data, you need to make sure your application is reading data from the DRAFT stage, and that you don't have a caching layer when you're in preview mode.

Without this, your requests will be cached and so you will always see stale data in the UI.

Here are some recommendations:

• API permissions: Make sure you define the permissions for our API correctly. You can create a token for preview and another for production.
• Preview token: In your Hygraph project, go to Project Settings > Access > Permanent Auth Tokens and create a new token for preview. You need to select DRAFT as the default stage. Once on the token page, make sure you initialize default permissions.
• Production token: Repeat the process to create a token, but this time select PUBLISHED as the default stage. Make sure to also initialize default permissions.

#Content API endpoint

While new projects can only see this endpoint, old ones can see - and could be using - the legacy endpoint.

You can find the High Performance Content API endpoint in Project Settings > Access > API Access.

Click here to learn more about our high performance endpoint.

#Frontend implementation

To be able to use side-by-side visual preview in your frontend implementation, you have to query the GraphQL endpoint for your page in the DRAFT stage rather than the PUBLISHED stage.

Ways to query the DRAFT stage

• Create a URL for your web app that queries the DRAFT stage of your endpoint. This could look like: https://preview.yourwebsite.com. You could also use a query parameter on the URL, like this: https://yourwebsite.com?preview=true.
• Create a permission on another content API endpoint that by default returns the DRAFT stage in the context of preview. Use that in the web app you want to do preview with.
• Change from PUBLISHED to DRAFT in your app based on a preview context inside your frontend.

#Next.js

In Next.js we have the concept of draftMode from the next/headers package. This mode sets a cookie in the browser to enable itself.

import { draftMode, cookies } from 'next/headers';
import { redirect } from 'next/navigation';

export async function GET(request) {
  const { searchParams } = new URL(request.url);
  const previewToken = searchParams.get('previewToken');
  const slug = searchParams.get('slug');

  // Check for a slug and for a preview token
  if (!previewToken || !slug) {
    return new Response('Invalid token', { status: 401 });
  }

  // Get the slug from Hygraph to ensure we don't run into redirect loops
  const res = await fetch(process.env.HYGRAPH_ENDPOINT, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      query: `
      query SinglePage($slug: String!) {
        page(where: { slug: $slug }, stage: DRAFT) {
          slug
        }
      }
      `,
      variables: { slug },
    }),
  });

  // Return the data
  const { data } = await res.json();

  // If the data returns in undefined or in the wrong shape, return an error
  if (!data || !data.page) {
    return new Response('Invalid slug', { status: 401 });
  }

  // Workaround for https://github.com/vercel/next.js/issues/49927
  // Enable draft mode as usual
  draftMode().enable();

  // Update the cookie and set same site to none so we can render it inside Hygraph
  const cookieStore = cookies();
  const cookie = cookieStore.get('__prerender_bypass');
  cookies().set({
    name: '__prerender_bypass',
    value: cookie?.value,
    httpOnly: true,
    path: '/',
    secure: true,
    sameSite: 'none',
  });

  redirect(`/${data.page.slug}`);
}

Once draftMode is set up you can amend your GraphQL queries so they can query for the DRAFT or PUBLISHED stages.

If you prefer, to make things easier so you don't need to update all your queries, you can also use the strategy we shared before, of having two tokens. If isEnabled is true, you can conditionally change the token.

In /app/page.tsx:

import { request } from 'graphql-request';
import { draftMode } from 'next/headers';

// isEnabled is true if the cookie has been set.
// See: https://nextjs.org/docs/app/building-your-application/configuring/draft-mode
const { isEnabled } = draftMode();

const query = `
  query Page($slug: String!, $stage: Stage! = PUBLISHED) {
    page(where: { slug: $slug }, stage: $stage) {
      title
      description
	  }
	}
)`;

const variables = {
  stage: isEnabled ? 'DRAFT' : 'PUBLISHED',
  slug: '/about',
};

const { data: page } = await request(HYGRAPH_ENDPOINT, query, variables);

Next preview URL structure

The preview URL you set up in the sidebar configuration of your schema would look like this:

https://yourwebsite.com/api/draft?secret=MY_SECRET_TOKEN&slug={slug}

#Nuxt

Nuxt has a similar setup to Next.js and can put itself in preview mode as well. The below example is the simplest version. You will see this approach used by many CMS implementations.

Create a Nuxt plugin in the plugins folder like so: /plugins/review.ts. Nuxt will automatically read it once it starts up.

export default defineNuxtPlugin((nuxtApp) => {
  const route = useRoute();
  const preview = route.query.preview && route.query.preview === 'true';

  if (preview) {
    nuxtApp.hook('page:finish', () => {
      refreshNuxtData();
    });
  }

  return { provide: { preview } };
});

This plugin looks at the query string ?preview=true and based on that provides a global preview variable to the whole app.

The variable $preview is now available in all components.

In /pages/about.vue, you can do the following to decide what stage you want to query:

<script setup>
import { request } from "graphql-request";

// See previous code block for how to enable $preview
const { $preview } = useNuxtApp();

const query = `
  query Page($slug: String!, $stage: Stage! = PUBLISHED) {
    page(where: { slug: $slug }, stage: $stage) {
      title
      description
	  }
	}
)

const variables = {
	"stage": $preview ? "DRAFT" : "PUBLISHED",
	"slug": "/about"
}

const { data: page } = await request(
  HYGRAPH_ENDPOINT,
  query,
  variables
);
</script>
<template>
	<h1>{{ page.title }}</h1>
	<p>{{ page.description }}</p>
</template>

Nuxt preview URL structure

The preview URL you set up in the sidebar configuration of your schema would look like this:

https://yourwebsite.com/{slug}?preview=true

#Astro

Astro is generally focused on SSG rendering (static pages) and due to its incredible flexibility in terms of using frontend frameworks, there is no official “preview mode”.

To make it work with Hygraph:

1. Use output: 'server' to render the Astro site in SSR mode
2. Set an ENV variable for preview to true. For example: ASTRO_USE_PREVIEW and based on that set your stage from PUBLISHED to DRAFT.

As the site runs in SSR mode it will always query the DRAFT endpoint for fresh data.

In astro.config.mjs:

import { defineConfig } from 'astro/config';
import vercel from '@astrojs/vercel/serverless';

export default defineConfig({
  output: 'server',
  adapter: vercel(),
});

In /src/pages/page.astro:

---
import { request } from "graphql-request";

const isPreview = import.meta.env.ASTRO_USE_PREVIEW === 'yes';

const query = `
  query Page($slug: String!, $stage: Stage! = PUBLISHED) {
    page(where: { slug: $slug }, stage: $stage) {
      title
      description
	  }
	}
)`

const variables = {
	"stage": $preview ? "DRAFT" : "PUBLISHED",
	"slug": "/about"
}

const { data: page } = await request(
  HYGRAPH_ENDPOINT,
  query,
  variables
);
---

<html>
	<head>
		<title>{page.title}</title>
	</head>

	<body>
		<main>
			<article>
				<h1>{page.title}</h1>
				<p>{page.description}</p>
			</article>
		</main>
	</body>
</html>

Astro preview URL structure

Since you cannot set Astro to a preview mode like Next and Nuxt, what you will do is make it read from the DRAFT stage and set an ENV variable in the build system that says to query DRAFT. You should also configure the output: 'server' setting in the config.

You will then configure your preview URL in the sidebar by creating a URL for your web app that queries the DRAFT stage of your endpoint. This could look like this: https://preview.yourwebsite.com or it could have a query parameter in the URL like this: https://yourwebsite.com?preview=true.

Preview URL structure example:

https://preview.yourwebsite.com/{slug}