Set up Live Preview for Your Website

Live Preview lets you preview the changes made to your entry before they're published to the live site. Content managers can preview draft content in real-time across multiple digital channels.

Note: The Live Preview feature currently works only for web-based applications. We will provide support for mobile-based applications in the future.

In this guide, we will learn how to set up the Live Preview feature for your stack using various frameworks with our SDKs.

Process overview

We have a detailed step-by-step guide on how to set up Live Preview for your stack using three set up methods:

Server-side Rendering (SSR)
Client-side Rendering (CSR)
Gatsby-powered Sites

Let’s get started!

Prerequisites

Contentstack account
Access to stack settings
Management Token
Website that uses Contentstack Delivery SDKs
IFrame-compatible website to avoid CORS errors

Server-side Rendering (SSR)

Server-side rendering (SSR) is the process where an application converts HTML files on a server instead of a browser into a rendered HTML client page. This guide explains in detail how to set up Live Preview for your SSR websites.

Steps for Execution

Set up the SSR Website
Host the SSR Website
Update Stack Settings for the SSR Website

Set up the SSR Website

You must first set up your website. To do so, follow these steps given below:

Generate a management token for configuration
Generate Management Token under Settings | Tokens | Management Tokens in the Contentstack app. It is recommended to use a read-only management token for Live Preview to prevent any unauthorized data change.
Update Contentstack's delivery SDK
Add Live Preview configs to the Contentstack.Stack() method of Contentstack's delivery SDK, e.g., here is a sample code for the JavaScript Delivery SDK:
```
import Contentstack from 'contentstack'

const Stack = Contentstack.Stack({ 
  ...
  // update your configs here
  live_preview: {
    management_token: management_token,
    enable: true,
    host: 'api.contentstack.io'
  },
  ...
})
```
Note: Set the host parameter to api.contentstack.io for the North America endpoint. If your website is hosted on the European data center, then pass eu-api.contentstack.com.
Set host to Contentstack's API server
After creating the Stack object, set the host that points the SDK to Contentstack's API server. To set the host to the North America endpoint, use the following code:
```
Stack.setHost("api.contentstack.io")
```
To point the host to the European endpoint, you can use the following code:
```
Stack.setHost("eu-api.contentstack.com")
```
Install/Initialize the Live Preview Utils SDK
The Live Preview Utils SDK listens to content changes and requests Contentstack's delivery SDK to fetch draft or preview content or process real-time content changes. Therefore, this SDK needs to be executed on the client side.

To install it, you can either use npm or import it using the script tag in your HTML page code.

Using script tag: To import the Live Preview Utils SDK using the script tag of the HTML file, add the following code:
```
<script src="https://unpkg.com/@contentstack/live-preview-utils/dist/index.js"></script>
```
Then, you can initialize the SDK using the init() method and set the enable key to true.
```
<script>
    ContentstackLivePreview.init({
        enable: true,
        });
</script>
```
Using npm: Alternatively, you can install the Live Preview Utils SDK package via npm using the following command:
```
npm install @contentstack/live-preview-utils
```
You can then initialize the SDK using the init() method. This method helps set up event listeners that keep a tab of any changes made to the previewed entry's content. Set the enable key to true.
```
import ContentstackLivePreview from "@contentstack/live-preview-utils";

ContentstackLivePreview.init({
    enable: true,
});
```
Note: You need to define your SDK initialization code within a separate JavaScript file to prevent configuration resetting errors in your Live Preview setup caused by rerendering.
Set up a middleware
Set up a middleware to track all new changes being made to the entry content. This middleware injects the Live Preview hash and content type UID into the Stack class using the livePreviewQuery() method.
```
app.use((req, response, next) => {
       // this will get live_preview hash and ContentType to the request
       Stack.livePreviewQuery(req.query);
       next();
   });
```

With these steps, we have the user website ready. Let's move ahead and host this website.

Host the SSR Website

To host a website, you can simply use ngrok or any other website hosting service.

Note: Make sure your website is HTTPS enabled.

Update Stack Settings for the SSR Website

To enable Live Preview through the stack settings in Contentstack, follow the steps given below:

Go to Settings.
Create a new environment if there are no existing environments in your stack.
Add your hosted website URL as the base URL for the environment created.
Navigate to the Live Preview section under stack's "Settings".
Select the Enable Live Preview checkbox.
If needed, you can select a default URL and environment for previewing live content across all entries of your stack. This helps avoid having to add the preview settings manually across multiple entries.
Tip: You can also update the preview URL and environment from the preview settings available on the entry page.
Save the settings.

Tip: Once you have set up Live Preview for your stack, you can refer to the Live Editing for Entries section to learn how to set up real-time content editing and preview for stack entries.

You will now be able to see the Live Preview icon within all the entries of your stack and the feature will preview data from the hosted website.

Client-side Rendering (CSR)

Client-side rendering (CSR) is where developers render their content directly to a browser using JavaScript. This guide explains in detail how to set up Live Preview for your CSR websites.

Steps for Execution

Set up the CSR Website
Host the CSR Website
Update Stack Settings for the CSR Website

Set up the CSR Website

Generate a management token for configuration
Management token can be generated under Settings | Tokens | Management Tokens in the Contentstack app. It is recommended to use a read-only management token for Live Preview to prevent any unauthorized data change.
Update Contentstack's delivery SDK
Add Live Preview configs to the Contentstack.Stack() method of Contentstack's delivery SDK, e.g., here is a sample code for the JavaScript Delivery SDK:
```
import Contentstack from 'contentstack'

const Stack = Contentstack.Stack({ 
  ...
  // update your configs here
  live_preview: {
    management_token: management_token,
    enable: true,
    host: 'api.contentstack.io'
  },
  ...
})
```
Note: Set the host parameter to api.contentstack.io for the North America endpoint. If your website is hosted on the European data center, then pass eu-api.contentstack.com.
Set host to Contentstack's API server
After creating the Stack object, set the host that points the SDK to Contentstack's API server. To set the host to the North America endpoint, use the following code:
```
Stack.setHost("api.contentstack.io")
```
To point the host to the European endpoint, you can use the following code:
```
Stack.setHost("eu-api.contentstack.com")
```
Install and Initialize the Live Preview Utils SDK
The Live Preview Utils SDK listens to content changes and requests Contentstack's delivery SDK to fetch draft or preview content or process real-time content changes. Therefore, this SDK needs to be executed on the client side.

To install it, you can either use npm or import it using the script tag in your HTML page code.

Using script tag: To import the Live Preview Utils SDK using the script tag of the HTML file, add the following code:
```
<script src="https://unpkg.com/@contentstack/live-preview-utils/dist/index.js"></script>
```
Then, you can initialize the SDK using the init() method and set the enable key to true.
```
<script>
    ContentstackLivePreview.init({
        enable: true,
        });
</script>
```
Using npm: Alternatively, you can install the Live Preview Utils SDK package via npm using the following command:
```
npm install @contentstack/live-preview-utils
```
You can then initialize the SDK using the init() method. This method helps set up event listeners that keep a tab of any changes made to the previewed entry's content.

Set the enable key to true and pass the Stack object against the stackSDK parameter.
```
import ContentstackLivePreview from "@contentstack/live-preview-utils";

ContentstackLivePreview.init({
    enable: true,
    stackSdk: Stack,
    ssr: false,
});
```
Note: You need to define your SDK initialization code within a separate JavaScript file to prevent configuration resetting errors in your Live Preview setup caused by rerendering.
Configure Live Preview across each webpage
Whenever you update an entry, the onEntryChange() method will be executed. You can define any coding logic that helps fetch data inside this method.

Each page has a function responsible for retrieving data and setting it to the state. Here, we have used React.js for demonstration. We have created an updateData() function responsible for fetching the data and setting it to React state.

Now, inside the useEffect function, we pass the updateData function against the onEntryChange() method. This onEntryChange() method runs the updateData() function every time you update entry content.
```
// utils.js
...
export const onEntryChange = ContentstackLivePreview.onEntryChange;
...

// Footer.js
import React from "react";
import { onEntryChange } from "./utils.js";

const Footer = () => {
    const [data, setData] = React.useState({});

    const updateData = () => {
        const fetchedData = SomeCallToGetData();
        setData(fetchedData);
    };

    React.useEffect(() => {
        onEntryChange(updateData);
    }, []);

    return <div>{data.company_name}</div>;
};
```

Host the CSR Website

To host a website, you can simply use ngrok or any other website hosting service.

Update Stack Settings for the CSR Website

To enable Live Preview through the stack settings in Contentstack, follow the steps given below:

Go to Settings.
Create a new environment if there are no existing environments in your stack.
Add your hosted website URL as the base URL for the environment created.
Navigate to the Live Preview section under stack's "Settings".
Select the Enable Live Preview checkbox.
If needed, you can select a default URL and environment for previewing live content across all entries of your stack. This helps avoid having to add the preview settings manually across multiple entries.
Tip: You can also update the preview URL and environment from the preview settings available on the entry page.
Save the settings.

Tip: Once you have set up Live Preview for your stack, you can refer to the Live Editing for Entries section to learn how to set up real-time content editing and preview for stack entries.

You will now be able to see the Live Preview icon within all the entries of your stack and the feature will preview data from the hosted website.

Gatsby-powered Sites

Gatsby is an open-source framework that combines functionality from React, GraphQL and Webpack into a single tool for building static websites and apps. This guide explains in detail how to set up Live Preview for your Gatsby-powered websites.

Steps for Execution

Set up the Gatsby-powered Website
Host the Gatsby-powered Website
Update Stack Settings for the Gatsby-powered Website

Set up the Gatsby-powered Website

Generate a management token for configuration
Management Token can be generated under Settings | Tokens | Management Tokens in the Contentstack app. It is recommended to use a read-only management token for Live Preview to prevent any unauthorized data change.
Update Contentstack's delivery SDK
Add Live Preview configs to the Contentstack.Stack() method of Contentstack's delivery SDK, e.g., here is a sample code for the JavaScript Delivery SDK:
```
import Contentstack from 'contentstack'

const Stack = Contentstack.Stack({ 
  ...
  // update your configs here
  live_preview: {
    management_token: management_token,
    enable: true,
    host: 'api.contentstack.io'
  },
  ...
})
```
Note: Set the host parameter to api.contentstack.io for the North America endpoint. If your website is hosted on the European data center, then pass eu-api.contentstack.com.
Set host to Contentstack's API server
After creating the Stack object, set the host that points the SDK to Contentstack's API server. To set the host to the North America endpoint, use the following code:
```
Stack.setHost("api.contentstack.io")
```
To point the host to the European endpoint, you can use the following code:
```
Stack.setHost("eu-api.contentstack.com")
```
Install and Initialize the Live Preview Utils SDK
The Live Preview Utils SDK listens to content changes and requests Contentstack's delivery SDK to fetch draft or preview content or process real-time content changes. Therefore, this SDK needs to be executed on the client side.

To install it, you can either use npm or import it using the script tag in your HTML page code.

Using script tag: To import the Live Preview Utils SDK using the script tag of the HTML file, add the following code:
```
<script src="https://unpkg.com/@contentstack/live-preview-utils/dist/index.js"></script>
```
Then, you can initialize the SDK using the init() method and set the enable key to true.
```
<script>
    ContentstackLivePreview.init({
        enable: true,
        });
</script>
```
Using npm: Alternatively, you can install the Live Preview Utils SDK package via npm using the following command:
```
npm install @contentstack/live-preview-utils
```
You can then initialize the SDK using the init() method. This method helps set up event listeners that keep a tab of any changes made to the previewed entry's content.

Set the enable key to true and pass the Stack object against the stackSDK parameter.
```
import ContentstackLivePreview from "@contentstack/live-preview-utils";

ContentstackLivePreview.init({
    enable: true,
    stackSdk: Stack,
    ssr: false,
});
```
Note: You need to define your SDK initialization code within a separate JavaScript file to prevent configuration resetting errors in your Live Preview setup caused by rerendering.
Configure Live Preview across each webpage
Whenever you update an entry, the onEntryChange() method will be executed. Hence, you can define any coding logic that helps fetch data inside this method.

Each page has a function responsible for retrieving data and setting it to the state. Here, we have used React.js for demonstration. We have created an updateData() function responsible for fetching the data and setting it to React state.

Now, inside the useEffect function, we pass the updateData function against the onEntryChange() method. This onEntryChange method runs the updateData() function every time you update entry content.
```
// utils.js
...
export const onEntryChange = ContentstackLivePreview.onEntryChange;
...

// Footer.js
import React from "react";
import { onEntryChange } from "./utils.js";

const Footer = () => {
    const [data, setData] = React.useState({});

    const updateData = () => {
        const fetchedData = SomeCallToGetData();
        setData(fetchedData);
    };

    React.useEffect(() => {
        onEntryChange(updateData);
    }, []);

    return <div>{data.company_name}</div>;
};
```

Finally, Gatsby primarily gets its data from contentstack-source-plugin. But, Live Preview currently works only on JavaScript Content Delivery SDK. Hence, for Gatsby, we fetch the data from the contentstack SDK, store it to React state, and rerender the page using the onEntryChange() method.

The data format remains different for the Gatsby source plugin. It requires a prefix and the entry names are in Camel case. Hence, we use getGatsbyDataFormat() to convert the entry's name.

It takes the Contentstack Stack object as the first parameter and the prefix as the second. The prefix is set inside the gatsby-config.js file. The default value of the prefix is contentstack.

// for example:
const query = Stack.ContentType("your-contentype").Entry("entry-uid");

const formattedData = ContentstackLivePreview.getGatsbyDataFormat(
    query,
    "contentstack"
);

setData(formattedData);

Together, the code will look as follows:

// utils.js
...
export const onEntryChange = ContentstackLivePreview.onEntryChange;
...

// Footer.js
import React from "react";
import { onEntryChange } from "./utils.js";

const Footer = () => {
    const [data, setData] = React.useState({});

    const updateData = () => {
        const query = Stack.ContentType("your-contentype").Entry("entry-uid");

      const fetchedData = ContentstackLivePreview.getGatsbyDataFormat(
    query,
    "contentstack"
);

        setData(fetchedData);
    };

    React.useEffect(() => {
        onEntryChange(updateData);
    }, []);

    return <div>{data.company_name}</div>;
};

Host the Gatsby-powered Website

To host a website, you can simply use ngrok or any other website hosting service.

Update Stack Settings for the Gatsby-powered Website

To enable Live Preview through the stack settings in Contentstack, follow the steps given below:

Go to Settings.
Create a new environment if there are no existing environments in your stack.
Add your hosted website URL as the base URL for the environment created.
Navigate to the Live Preview section under stack's "Settings".
Select the Enable Live Preview checkbox.
If needed, you can select a default URL and environment for previewing live content across all entries of your stack. This helps avoid having to add the preview settings manually across multiple entries.
Tip: You can also update the preview URL and environment from the preview settings available on the entry page.
Save the settings.

Tip: Once you have set up Live Preview for your stack, you can refer to the Live Editing for Entries section to learn how to set up real-time content editing and preview for stack entries.

You will now be able to see the Live Preview icon within all the entries of your stack and the feature will preview data from the hosted website.

Live Edit Tags for Entries (optional)

Live edit tags allow you to navigate to the field that contains the website content being previewed within the Live Preview pane. When you click on the "Edit" button beside a content block in the preview pane, you will be redirected to the corresponding field within the entry. If the field holds reference to another entry, you will be redirected to the referenced entry's editor page.

Edit tags contain the location where the corresponding field lies within the entry. The Live Preview Utils SDK searches for the elements which contain the edit tags referred to as data-cslp.

The structure of the edit tag (field location in the entry) you can pass against the data-cslp attribute is as follows:

{content_type_uid}.{entry_uid}.{locale}.{field_uid}

Here's a sample field path:

home.blt80654132ff521260.en-us.modular_blocks.block_1.media_group_uid.image_uid

Note: If the field is nested within another complex field, such as Modular Blocks, provide the field path as follows: {modular_block_field_UID}.{block_UID}.{field_UID}.

For a website built using Contentstack's JavaScript Delivery SDK, we use the addEditableTags() method to automatically generate the edit tag for you. The following section explains how you can set up live edit tags using addEditableTags().

Set Up Live Editing Using the addEditableTags Method

Locate the Stack.ContentType() method
Firstly, navigate to the website code where the JavaScript Delivery SDK delivers entry content, and move to the section where you use the Stack.ContentType() method.

Here is a sample code for the Stack.ContentType() method:
```
let entry = await Stack.ContentType("content_type_uid").Query()
            .where("url", URL)
            .find();
```
Import the addEditableTags() method
Now, import the addEditableTags() method from the Contentstack SDK:
```
const Contentstack = require("contentstack");
Contentstack.Utils.addEditableTags()
```
Note: The addEditableTags() method is also available in the Contentstack JavaScript Utils SDK package.
Generate edit tags for previewed entry content
After retrieving data using the Contentstack JavaScript Delivery SDK, pass the resultant entry within the addEditableTags() function to add edit tags to the previewed entry content:
```
addEditableTags(entry, content_type_uid, tagsAsObject, locale)
```
Here, entry is the actual entry you get from the SDK, content_type_uid is the unique ID of the current entry’s content type, and tagsAsObject determines the format in which the edit tag would be added.

Note: The addEditableTags() method does not return any value. It only modifies the entry passed as the first argument to the method.

By default, tagsAsObject is set to false, and it appends data-cslp in the form of a string as follows:
```
'data-cslp=path.to.field'
```
Note: This option is provided for React-based apps as we cannot directly add any attributes in string format. Instead, we need to destructure an object.

If tagsAsObject is set to true, the data-cslp attribute is returned in object format as follows:
```
{ 'data-cslp': 'path.to.field'}
```
Here's a sample that shows how the code would look once you add the addEditableTags() method:
```
let entry = await Stack.ContentType("content_type_uid").Query()
            .where("url", URL)
            .find();

addEditableTags(entry[0][0], "content_type_uid", false)
```
When you use the addEditableTags() method, a new key-value pair is returned at every level in the existing entry schema. This pair is known as the edit tag and is denoted by a dollar sign ($).

For example, consider that you passed the following entry schema against the first parameter in the addEditableTags() method:
```
{
    "name": "John Doe",
    "description": {
        "occupation": [{
            "name": "Plumber",
            "since": 1920
        }],
        "height": "5ft"
    }
}
```
Once the addEditableTags() method is executed, the entry passed against the first parameter is updated as follows:
```
{
    "name": "John Doe",
    "$": {
        "name": "profile.blt8tvsk328dbw258.en-us.name"
    },
    "description": {
        "$": {
            "occupation": "profile.blt8tvsk328dbw258.en-us.description.occupation",
            "height": "profile.blt8tvsk328dbw258.en-us.description.height"
        },
        "occupation": [{
            "$": {
                "name": "profile.blt8tvsk328dbw258.en-us.description.occupation.name",
                "since": "profile.blt8tvsk328dbw258.en-us.description.occupation.since"
            },
            "name": "Plumber",
            "since": 1920
        }],
        "height": "5ft"
    }
}
```
Set up the Live Preview Utils SDK
Live Preview requires the stack API key and host URL to perform appropriate redirection to the relevant stack.
```
ContentstackLivePreview.init({
    ...
    stackDetails: {
       apiKey: "your api key",
   },
   clientUrlParams: {
       protocol: "https",
       host: "app.contentstack.com",
       port: 443,
   },
})
```
Here, the ClientUrlParams key is optional and is set for the North America region. For European region, you can use the following config for clientUrlParams:
```
{
   host: "eu-app.contentstack.com",
}
```
Configure live edit tags for each webpage
Now, navigate to the section in your website's front-end HTML code where you need to pass the edit tags as attributes. To access an edit tag, fetch the path to a field in the entry and add a dollar sign ($) before the last field in the field depth hierarchy.

For example, if the path to your entry data is data.description.height, then the corresponding edit tag will be data.description.$.height.

Once you add the edit tag, content managers will be able to see the "Edit" icon whenever they hover over the corresponding content block on the website.
```
<header class="text-center">
    <div class="author">
        <img {{ data.author.profile_image.$.url }} src="{{ data.author.profile_image.url }}" alt="{{ data.author.title }}" />
    </div>
    <h1 {{ data.author.$.title }}>{{ data.author.title }}</h1>
    <h2 class="author-job" {{ data.author.$.job_title }}>{{ data.author.job_title }}</h2>
    <p class="author-bio" {{ data.author.$.biography }}>{{ data.author.biography }}</p>
    <div class="author-social">
        <a href="mailto:{{ data.author.social.email }}"><ion-icon name="mail-outline"></ion-icon></a>
        <a href="https://www.twitter.com/{{ data.author.social.twitter }}"><ion-icon name="logo-twitter"></ion-icon></a>
        <a href="https://www.instagram.com/{{ data.author.social.instagram }}"><ion-icon name="logo-instagram"></ion-icon></a>
    </div>
</header>
```
For React-based applications, we generate edit tags by setting the tagsAsObject parameter to true. When set to true, this parameter returns the edit tag in object format. You need to destructure the object while passing it within the JSX element.

Here is an example of an edit tag that is returned in object format:
```
<h1 {...data.$.name}>{data.name}</h1>
<p {...data.description.$.height}>{data.description.height}</p>
```
Note: This setup only works for generic websites that use basic JavaScript frontend code. For websites working on other programming languages, you need to provide the entire path to the specific field.
Add CSS to display edit buttons in the project
The styles for the live edit tags are available in the @contentstack/live-preview-utils/dist/main.css file. You can import these styles in your main index.js file using npm as follows:
```
import "@contentstack/live-preview-utils/dist/main.css";
```
Alternatively, you can directly import the CSS within the HTML using the following code:
```
<link rel="stylesheet" href="https://unpkg.com/@contentstack/live-preview-utils/dist/main.css">
```

Once you have configured the settings, you will be able to see the Edit icon whenever you hover over a content block in your preview pane.

Set Up Live Preview for Your Website

Process overview

Prerequisites

Server-side Rendering (SSR)

Set up the SSR Website

Host the SSR Website

Update Stack Settings for the SSR Website

Client-side Rendering (CSR)

Set up the CSR Website

Host the CSR Website

Update Stack Settings for the CSR Website

Gatsby-powered Sites

Set up the Gatsby-powered Website

Host the Gatsby-powered Website

Update Stack Settings for the Gatsby-powered Website

Live Edit Tags for Entries (optional)

Set Up Live Editing Using the addEditableTags Method

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