Get Started with Live Preview Utils SDK

Live Preview Utils SDK provides a utility function that listens to the entry change event fired from the contentstack app and updates the website accordingly. With this SDK, you can also configure the “Edit” button functionality.

Prerequisite

• Node.js version 4.4.7 or later

Installation and setup

Execute the below command to install the live-preview-utils package via npm:

npm install @contentstack/live-preview-utils

Alternatively, you can include the live-preview-utils package directly in your website HTML code as follows:

<script src="https://unpkg.com/@contentstack/live-preview-utils@1.4.0/dist/index.js"></script>

Initialize SDK

Since the Live Preview Utils SDK is responsible for communication, you only need to initialize it.

To do so, execute the below command:

import ContentstackLivePreview from "@contentstack/live-preview-utils";

ContentstackLivePreview.init({
    stackDetails: {
        apiKey: "your-stack-api-key"
    },
});

Alternatively, you can initialize the SDK directly inside the HTML tag using the ContentstackLivePreview.init() method as follows:

<script>
    ContentstackLivePreview.init({
        stackDetails: {
            apiKey: "your-stack-api-key"
        },
    });
</script>

init(config: IConfig)

The init() method initializes the Live Preview Utils SDK by setting up the necessary event listeners.

The init() method accepts a configuration object as a parameter. The following explains all the options available for the configuration.

enable

The enable property determines whether Live Preview communications have been enabled.

ssr

The ssr property determines the data update strategy for previewed content whenever you make changes to entry content. It depends on whether your app is SSR or CSR.

If you set the ssr property to true, your app or website is rendered from the server i.e., Server-side Rendering (SSR) and a request will be sent for a fresh HTML page every time you edit your content.

When you set the property to false, then the app is rendered from the client side i.e., Client-side Rendering (CSR). Your framework will fetch the data and reload the existing page.

Note: For CSR mode, stackSDK is required. Hence, you will automatically switch mode to CSR when you pass this object. This config is provided to override the default behavior.

editButton

The editButton object allows you to manage the "Edit" button both within and outside the Live Preview portal. It offers the following features:

• Enable/disable the "Edit" button
• Include/exclude the "Edit" button from inside/outside the Live Preview panel
• Adjust the position of the "Edit" button using eight over predefined positions

The editButton object contains four keys:

• enable

  This key lets you specify whether you want to display the “Edit” button or not. It is of type “Boolean” with the value true/false.

  type	default	optional
  boolean	true	no

• exclude

  This key provides you with the option to exclude the editButton from either inside or outside the Live Preview portal for certain conditions.

  type	default	optional
  array	[ ]	yes

  It is of type “Array” and takes one of the following string values:

  • insideLivePreviewPortal

    Used when you want to remove the “Edit” button from within the Live Preview portal.

  • outsideLivePreviewPortal

    Used when you want to remove the “Edit” button from outside the Live Preview portal.

  Note: Although you have excluded the "Edit" button for Live Preview, you can add the cslp-buttons query parameter in your website URL to display the "Edit" button outside of your Live Preview-enabled website.

• includeByQueryParameter

  This key is used to override the cslp-buttons query parameter. You can set this to true/false to enable/disable the "Edit" button option, respectively.

  type	default	optional
  boolean	true	yes

• position

  The user can place the "Edit" button in eight predefined positions within or over the Live Preview portal using these values: left, right, top-left (or top), top-right, top-center, bottom-left (or bottom), bottom-right, and bottom-center.

  type	default	optional
  string	top	yes

Note: The default position of the "Edit" button is set to "top". In a collaborative work environment, you can also manually position the “Edit” button on your website by applying the data-cslp-button-position attribute to the HTML tag with one of the position values.

For example:

ContentstackLivePreview.init({
    ...
    editButton: {
        enable: true,
        exclude: ["outsideLivePreviewPortal"],
        includeByQueryParameter: false,
        position:'top-right',
    }
});

cleanCslpOnProduction

When enable is set to false and cleanCslpOnProduction is set to true, the data-cslp attributes are removed from the website.

stackDetails

The stackDetails object contains stack related information that helps in redirecting to the corresponding entry whenever you use edit tags within your website.

If you do not use live edit tags, then you don't need to use the stackDetails property.

stackDetails {
    apiKey: string,
    environment: string
}

• apiKey

  The API key of the concerned stack.

  Note: This is required if you are using the live edit tags.

  type	optional
  string	yes (no, if you are using edit tags)

• environment

  The environment name of the concerned stack.

  type	optional
  string	yes (no, if you are using edit tags)

clientUrlParams

The clientUrlParams object contains the URL information of the stack that contains your webpage content. By default, the configuration details are set for the NA region.

//For North American region
{
    protocol: "https",
    host: "app.contentstack.com",
    port: 443
}
//For European region
{
    protocol: "https",
    host: "eu-app.contentstack.com",
    port: 443,
}
//For Azure EU region
{
    protocol: "https",
    host: "azure-eu-app.contentstack.com",
    port: 443,
}
//For Azure NA region
{
    protocol: "https",
    host: "azure-na-app.contentstack.com",
    port: 443,
}

Pass the clientUrlParams object only if you need to modify the URL.

stackSdk

The stackSdk object represents the Stack class that you get by executing the Contentstack.Stack() method. It is required for Client-Side Rendering (CSR) as we need to inject the Live Preview hash and content type UID into the Stack class.

Basic Queries

This section provides an overview of basic queries.

onLiveEdit(callback: () => void)

The onLiveEdit method modifies or alters the content inside the Live Preview panel as soon as a change is made in the entry. This method runs a single API request to retrieve draft content from the entry and display the changes in the Live Preview panel.

Note: The onLiveEdit method will not fetch the published content of the entry and is only applicable in the Client-Side Rendering (CSR) mode.

// utils.js
import ContentstackLivePreview from '@contentstack/live-preview-utils';
...
export const onLiveEdit = ContentstackLivePreview.onLiveEdit;

For Client-Side Rendering (CSR), as the framework handles data collection and rendering by itself, we recommend creating a function, say updateData(), to fetch data and pass it to the onLiveEdit() method. The onLiveEdit() method will execute the updateData() function whenever new data is available.

For example, in a React application, you can create an updateData() function that will fetch data from Contentstack and store it in a React state. Inside the useEffect() function, you need to call the onLiveEdit() method and pass the updateData() function to it.

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

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

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

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

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

onEntryChange(callback: () => void)

For Client-Side Rendering (CSR), data collection and rendering is handled by the framework itself. Hence, for CSR, we recommend creating a function responsible for fetching and storing data, for example, updatePage(), and passing it to the onEntryChange() method. This will execute the updatePage() function whenever new data is available.

Note: This function only works when SSR is set to false, indicating that the application is of type CSR.

// utils.js
import ContentstackLivePreview from '@contentstack/live-preview-utils';
...
export const onEntryChange = ContentstackLivePreview.onEntryChange;

For example, in a React application, you can create an updateData() function that will fetch data from Contentstack and store it in a React state. Inside the useEffect() function, you need to call the onEntryChange() method and pass the updateData() function to it.

// 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>;
};

Note: To make the onEntryChange() method work similarly to the onLiveEdit() method, you can utilize the optional parameter skipInitialRender:true. This will enable the function to only call the Contentstack API once.

Example:

onEntryChange(fetchData,{skipInitialRender:true})

getGatsbyDataFormat(sdkQuery: IStackSdk, prefix: string)

Gatsby primarily fetches data using the gatsby-source-contentstack plugin. But, Live Preview currently works only on the contentstack SDK.

Hence, for Gatsby, we fetch the data from the contentstack SDK and store it in React state. Post that, we re-render the page using the onEntryChange() method. As the data format is different for the gatsby-source-contentstack plugin, it returns a prefix and the entry name in Camel case. Hence, we use getGatsbyDataFormat() to change the entry's name.The getGatsbyDataFormat() method accepts 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 set for the prefix is contentstack.

Example:

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

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

setData(formattedData);

Difference in data:

// not passed to function
{
  "footer_lib": {
    "title": "footer",
    ...
  }
}

// passed to function with prefix as 'contentstack'
{
  "contentstackFooterLib": {
    "title": "footer",
    ...
  }
}