YjsNode.jsTutorialsWebhooksDatabases

How to synchronize your Liveblocks Yjs document data to a Vercel Postgres database

Liveblocks allows you to build collaborative applications with Yjs, which is tightly integrated into our infrastructure. Using our webhooks and REST API, you can then retrieve the Yjs document data as it changes, and store it in your database.

What we’re building

In this guide we’ll be linking a Yjs application up to a Vercel Postgres database so that Yjs document data is automatically synchronized. This is enabled through the following:

This specific webhook is throttled

Note that the YDocUpdated webhook event is throttled at a rate of once every 5 seconds. This is because Yjs can update up to 60 times per second, and it would be impractical to run the webhook this frequently.

Create an endpoint in your project

When a webhook event is triggered, it can send a POST request to the back end in your project, and from within there we can update the database. In this guide, we’ll be using a Next.js route handler (API endpoint) as an example, but other frameworks work similarly.

In order to use webhooks, we’ll need to retrieve the headers and body from the request. Here’s the basic endpoint we’ll be starting from:

export async function POST(request: Request) {  const body = await request.json();  const headers = request.headers;
  // Handle webhooks and database  // ...
  return new Response(null, { status: 200 });}

Create this endpoint in your project, and make it available on localhost at the following URL:

/api/liveblocks-database-sync

Testing webhooks locally

Running webhooks locally can be difficult, but one way to do this is to use a tool such as localtunnel or ngrok which allow you to temporarily put your localhost server online.

If your project is running on localhost:3000, you can run the following command to generate a temporary URL that’s available while your localhost server is running:

$npx localtunnel --port 3000

localtunnel generates a base URL that can be placed into the Liveblocks webhooks dashboard for quick testing. To use this, take the full address of your webhook endpoint, and replace the domain in your localhost address with the generated URL.

# Take your local URLhttp://localhost:3000/api/liveblocks-database-sync
# Replace localhost with the generated domain, then copy ithttps://my-localtunnel-url.loca.lt/api/liveblocks-database-sync

You now have a URL that can be used in the webhooks dashboard.

Set up webhooks on the Liveblocks dashboard

To use webhooks, you need to pass your endpoint URL to the webhooks dashboard inside your Liveblocks project, and tell the webhook to trigger when Yjs document data has changed.

  1. Select your project

    From the Liveblocks dashboard, navigate to the project you’d like to use with webhooks, or create a new project.

    Create a Liveblocks project

  2. Go to the webhooks dashboard

    Click on the “Webhooks” tab on the menu at the left.

    Click webhooks

  3. Create an endpoint

    Click the “Create endpoint…” button on the webhooks dashboard to start setting up your webhook.

    Click add endpoint

  4. Add your endpoint URL

    Enter the URL of the endpoint. In a production app this will be the real endpoint, but for now enter your localtunnel URL from earlier.

    Add endpoint URL

  5. Get your webhook secret key

    Click “Create endpoint” at the bottom, then find your “Webhook secret key” on the next page, and copy it.

    Copy your webhook secret key

  6. Webhooks dashboard is set up!

    Note that you can filter specifically for ydocUpdated events, but we’re ignoring this for now so we can test more easily. Let’s go back to the code.

Verify the webhook request

The @liveblocks/node package provides you with a function that verifies whether the current request is a real webhook request from Liveblocks. You can set this up by setting up a WebhookHandler and running verifyRequest.

Make sure to add your “Signing Secret” from the Liveblocks dashboard—in a real project we’d recommend using an environment variable for this.

import { WebhookHandler } from "@liveblocks/node";
// Add your signing key from a project's webhooks dashboardconst WEBHOOK_SECRET = "YOUR_SIGNING_SECRET";const webhookHandler = new WebhookHandler(WEBHOOK_SECRET);
export async function POST(request: Request) {  const body = await request.json();  const headers = request.headers;
  // Verify if this is a real webhook request  let event;  try {    event = webhookHandler.verifyRequest({      headers: headers,      rawBody: JSON.stringify(body),    });  } catch (err) {    console.error(err);    return new Response("Could not verify webhook call", { status: 400 });  }
  // Update database  // ...
  return new Response(null, { status: 200 });}

We can then check we’re receiving the correct type of event, get the updated roomId, and handle updating the database inside there.

import { WebhookHandler } from "@liveblocks/node";
// Add your signing key from a project's webhooks dashboardconst WEBHOOK_SECRET = "YOUR_SIGNING_SECRET";const webhookHandler = new WebhookHandler(WEBHOOK_SECRET);
export async function POST(request: Request) {  const body = await request.json();  const headers = request.headers;
  // Verify if this is a real webhook request  let event;  try {    event = webhookHandler.verifyRequest({      headers: headers,      rawBody: JSON.stringify(body),    });  } catch (err) {    console.error(err);    return new Response("Could not verify webhook call", { status: 400 });  }
  // When Yjs document data has been updated  if (event.type === "ydocUpdated") {    const { roomId } = event.data;
    // Update database    // ...  }
  return new Response(null, { status: 200 });}

Get the current room’s Yjs document data

Before updating our database, we need to get the current room’s data. We can do this through the Get Yjs Document REST API. You use the REST API, you need to add your secret key from your project page.

import { WebhookHandler } from "@liveblocks/node";
// Add your signing key from a project's webhooks dashboardconst WEBHOOK_SECRET = "YOUR_SIGNING_SECRET";const webhookHandler = new WebhookHandler(WEBHOOK_SECRET);
// Add your secret key from a project's API keys dashboardconst API_SECRET = "";
export async function POST(request: Request) {  const body = await request.json();  const headers = request.headers;
  // Verify if this is a real webhook request  let event;  try {    event = webhookHandler.verifyRequest({      headers: headers,      rawBody: JSON.stringify(body),    });  } catch (err) {    console.error(err);    return new Response("Could not verify webhook call", { status: 400 });  }
  // When Yjs document data has been updated  if (event.type === "ydocUpdated") {    const { roomId } = event.data;
    // Get Yjs data from Liveblocks REST API    const url = `https://api.liveblocks.io/v2/rooms/${roomId}/ydoc`;    const response = await fetch(url, {      headers: { Authorization: `Bearer ${API_SECRET}` },    });
    if (!response.ok) {      return new Response("Problem accessing Liveblocks REST APIs", {        status: 500,      });    }
    // Your JSON Yjs document data as a string    const yDocData = await response.text();
    // Update database    // ...  }
  return new Response(null, { status: 200 });}

Create a Vercel Postgres database

We’re ready to set up our database! This is how to get started with Vercel Postgres:

  1. Navigate to the Vercel Storage dashboard.

  2. Click "Create Database", then select “Postgres”.
  3. Give the database a name and click “Create”.

  4. Follow the getting started guide to connect the database to your Vercel project, link your environment variables, and install the packages.

Add the Yjs data to your database

And finally, we can add the Yjs JSON data to our database. Here we’re creating a simple documents table that contains the following fields:

FieldDescriptionTypeKey
roomIdThe roomId.VARCHAR(255)PRIMARY
yDocDataThe stringified JSON Yjs data.TEXT

This is how to implement it in your endpoint:

import { WebhookHandler } from "@liveblocks/node";import { sql } from "@vercel/postgres";
// Add your signing key from a project's webhooks dashboardconst WEBHOOK_SECRET = "YOUR_SIGNING_SECRET";const webhookHandler = new WebhookHandler(WEBHOOK_SECRET);
// Add your secret key from a project's API keys dashboardconst API_SECRET = "";
export async function POST(request: Request) {  const body = await request.json();  const headers = request.headers;
  // Verify if this is a real webhook request  let event;  try {    event = webhookHandler.verifyRequest({      headers: headers,      rawBody: JSON.stringify(body),    });  } catch (err) {    console.error(err);    return new Response("Could not verify webhook call", { status: 400 });  }
  // When Yjs document data has been updated  if (event.type === "ydocUpdated") {    const { roomId } = event.data;
    // Get Yjs data from Liveblocks REST API    const url = `https://api.liveblocks.io/v2/rooms/${roomId}/ydoc`;    const response = await fetch(url, {      headers: { Authorization: `Bearer ${API_SECRET}` },    });
    if (!response.ok) {      return new Response("Problem accessing Liveblocks REST APIs", {        status: 500,      });    }
    // Your JSON Yjs document data as a string    const yDocData = await response.text();
    // Update database    try {      await sql`        CREATE TABLE IF NOT EXISTS documents (          roomId VARCHAR(255) PRIMARY KEY,          yDocData TEXT NOT NULL        );      `;      await sql`        INSERT INTO documents (roomId, yDocData)        VALUES (${roomId}, ${yDocData})        ON CONFLICT (roomId)        DO UPDATE SET          yDocData = EXCLUDED.yDocData      `;    } catch (err) {      return new Response("Problem inserting data into database", {        status: 500,      });    }  }
  return new Response(null, { status: 200 });}

Check if it worked

To check if your database synchronization is working, you can replay a yDocUpdated event from the Liveblocks dashboard.

Create your table schema

Then go to the Data page on your Vercel Postgres dashboard, find your table in the dropdown, and check the entries. You should now see your Yjs document—we’ve successfully set up data synchronization!

When a user edits Yjs data in your app, this function will be called, and your database will be updated. You can rely on this to stay up to date, within the 5 second throttle limit.

Learn more

You can learn more about Liveblocks webhooks in our full webhooks guide. We also have an API reference for the Get Yjs Document API.

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