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Getting Started With WebSockets ​

You can connect to a Directus project using a WebSocket interface and get updates on data held in a collection in real-time.

This guide will show you how to get started with Directus' WebSockets interface and JavaScript. WebSockets are language-agnostic, so you can apply the same set of steps in your stack of choice.

Before You Begin ​

You will need a Directus project. If you don’t already have one, the easiest way to get started is with our managed Directus Cloud service. You can also self-host Directus, ensuring the WEBSOCKETS_ENABLED environment variable is set to true.

Create a new collection called messages, with a date_created field enabled in the Optional Fields pane on collection creation. Create an input field called text and a second called user.

If it doesn’t already exist, create a user with a role that can execute read and create operations on the collection.

Finally in the Directus Data Studio, create a static access token for the user, copy it, and save the user profile.

Create an index.html file and open it in your code editor. Add the following boilerplate code:

html
<!DOCTYPE html>
<html>
	<body>
		<script>
			const url = 'wss://your-directus-url/websocket';
			const access_token = 'your-access-token';
			const collection = 'messages';
		</script>
	</body>
</html>
<!DOCTYPE html>
<html>
	<body>
		<script>
			const url = 'wss://your-directus-url/websocket';
			const access_token = 'your-access-token';
			const collection = 'messages';
		</script>
	</body>
</html>

Make sure to replace your-directus-url and your-access-token with your project and user details.

Create a Connection ​

At the bottom of your <script>, add the following code to establish a new WebSocket connection:

js
const connection = new WebSocket(url);
const connection = new WebSocket(url);

To add some feedback, add the following event handlers below your connection variable:

js
connection.addEventListener('open', function () {
	console.log({ event: 'onopen' });
});

connection.addEventListener('message', function (message) {
	const data = JSON.parse(message.data);
	console.log({ event: 'onmessage', data });
});

connection.addEventListener('close', function () {
	console.log({ event: 'onclose' });
});

connection.addEventListener('error', function (error) {
	console.log({ event: 'onerror', error });
});
connection.addEventListener('open', function () {
	console.log({ event: 'onopen' });
});

connection.addEventListener('message', function (message) {
	const data = JSON.parse(message.data);
	console.log({ event: 'onmessage', data });
});

connection.addEventListener('close', function () {
	console.log({ event: 'onclose' });
});

connection.addEventListener('error', function (error) {
	console.log({ event: 'onerror', error });
});

Open index.html in your browser and open the Developer Tools. You should see the onopen event logged in the console.

Authenticate Your Connection ​

Once a connection is opened, you have to send a message to authenticate your session. If you don't, you'll receive a message indicating there was an authentication failure.

js
connection.addEventListener('open', function () {
	console.log({ event: 'onopen' });

	connection.send( 
		JSON.stringify({ 
			type: 'auth', 
			access_token, 
		}) 
	); 
});
connection.addEventListener('open', function () {
	console.log({ event: 'onopen' });

	connection.send( 
		JSON.stringify({ 
			type: 'auth', 
			access_token, 
		}) 
	); 
});

You should immediately receive a message in return to confirm. The connection is now authenticated and will remain open, ready to send and receive data.

Learn more about WebSocket authentication here.

Create a Subscription ​

After subscribing to collections over your connection, you will receive new messages whenever items in the collection are created, updated, or deleted.

At the bottom of your <script>, create a new function which subscribes to a collection:

js
function subscribe() {
	connection.send(
		JSON.stringify({
			type: 'subscribe',
			collection: 'messages',
			query: { fields: ['*'] },
		})
	);
}
function subscribe() {
	connection.send(
		JSON.stringify({
			type: 'subscribe',
			collection: 'messages',
			query: { fields: ['*'] },
		})
	);
}

Save your file, refresh your browser, and open your browser console. Run this function by typing:

js
subscribe();
subscribe();

You will receive a message in response to confirm the subscription has been initialized. Then, new messages will be sent when there’s an update on the collection.

Create Item ​

Create a new function that sends a message over the connection with a create action:

js
function createItem(text, user) {
	connection.send(
		JSON.stringify({
			type: 'items',
			collection: 'messages',
			action: 'create',
			data: { text, user },
		})
	);
}
function createItem(text, user) {
	connection.send(
		JSON.stringify({
			type: 'items',
			collection: 'messages',
			action: 'create',
			data: { text, user },
		})
	);
}

Save your file, refresh your browser, and open your browser console. Create a few new items by using your new function directly in the console:

js
createItem('Hello World!', 'Ben');
createItem('Hello Universe!', 'Rijk');
createItem('Hello Everyone Everywhere All At Once!', 'Kevin');
createItem('Hello World!', 'Ben');
createItem('Hello Universe!', 'Rijk');
createItem('Hello Everyone Everywhere All At Once!', 'Kevin');

Every time you create an item, you will receive a message in response with the new item as created in your Directus collection.

Directus Data Studio Content Module showing the Messages collection with three items in it - one for each time the above command was run in the console.

Get Latest Item ​

You can use your connection to perform all CRUD actions by using type: 'items' in the payload and including the respective action. Create a new function for reading the latest message:

js
function readLatestItem() {
	connection.send(
		JSON.stringify({
			type: 'items',
			collection: 'messages',
			action: 'read',
			query: { limit: 1, sort: '-date_created' },
		})
	);
}
function readLatestItem() {
	connection.send(
		JSON.stringify({
			type: 'items',
			collection: 'messages',
			action: 'read',
			query: { limit: 1, sort: '-date_created' },
		})
	);
}

Send the message over the connection by entering readLatestItem() your browser console. You will receive a message with the result of your query on the collection.

Pings To Keep Connection Active ​

You may have noticed that, periodically, you will receive a message with a type of ping. This serves two purposes:

  1. To act as a periodic message to stop your connection from closing due to inactivity. This may be required by your application technology stack.
  2. To verify that the connection is still active.

In order to prevent the connection from closing, you may reply with a pong event:

js
// Exemplary code
connection.addEventListener('message', (message) => {
	const data = JSON.parse(message.data);

	if (data.type === 'ping') {
		this.connection.send(
			JSON.stringify({
				type: 'pong',
			}),
		);
	}
});
// Exemplary code
connection.addEventListener('message', (message) => {
	const data = JSON.parse(message.data);

	if (data.type === 'ping') {
		this.connection.send(
			JSON.stringify({
				type: 'pong',
			}),
		);
	}
});

On Directus Cloud, this feature is enabled. If you are self-hosting, you can alter this behavior with the WEBSOCKETS_HEARTBEAT_ENABLED and WEBSOCKETS_HEARTBEAT_PERIOD environment variables.

You may wish to exclude these messages from your application logic.

In Summary ​

In this guide, you have successfully created a new WebSocket connection, authenticated yourself, and performed CRUD operations over the connection. You have also created your first subscription.

Learn more about subscriptions with WebSockets with Directus.

Full Code Sample ​

html
<!DOCTYPE html>
<html>
	<body>
		<script>
			const url = 'wss://your-directus-url/websocket';
			const access_token = 'your-access-token';
			const collection = 'messages';

			const connection = new WebSocket(url);

			connection.addEventListener('open', function () {
				console.log({ event: 'onopen' });
				connection.send(
					JSON.stringify({
						type: 'auth',
						access_token,
					})
				);
			});

			connection.addEventListener('message', function (message) {
				const data = JSON.parse(message.data);
				console.log({ event: 'onmessage', data });
			});

			connection.addEventListener('close', function () {
				console.log({ event: 'onclose' });
			});

			connection.addEventListener('error', function (error) {
				console.log({ event: 'onerror', error });
			});

			function subscribe() {
				connection.send(
					JSON.stringify({
						type: 'subscribe',
						collection: 'messages',
						query: {
							fields: ['*'],
						},
					})
				);
			}

			function createItem(text, user) {
				connection.send(
					JSON.stringify({
						type: 'items',
						collection: 'messages',
						action: 'create',
						data: { text, user },
					})
				);
			}

			function readLatestItem() {
				connection.send(
					JSON.stringify({
						type: 'items',
						collection: 'messages',
						action: 'read',
						query: { limit: 1, sort: '-date_created' },
					})
				);
			}
		</script>
	</body>
</html>
<!DOCTYPE html>
<html>
	<body>
		<script>
			const url = 'wss://your-directus-url/websocket';
			const access_token = 'your-access-token';
			const collection = 'messages';

			const connection = new WebSocket(url);

			connection.addEventListener('open', function () {
				console.log({ event: 'onopen' });
				connection.send(
					JSON.stringify({
						type: 'auth',
						access_token,
					})
				);
			});

			connection.addEventListener('message', function (message) {
				const data = JSON.parse(message.data);
				console.log({ event: 'onmessage', data });
			});

			connection.addEventListener('close', function () {
				console.log({ event: 'onclose' });
			});

			connection.addEventListener('error', function (error) {
				console.log({ event: 'onerror', error });
			});

			function subscribe() {
				connection.send(
					JSON.stringify({
						type: 'subscribe',
						collection: 'messages',
						query: {
							fields: ['*'],
						},
					})
				);
			}

			function createItem(text, user) {
				connection.send(
					JSON.stringify({
						type: 'items',
						collection: 'messages',
						action: 'create',
						data: { text, user },
					})
				);
			}

			function readLatestItem() {
				connection.send(
					JSON.stringify({
						type: 'items',
						collection: 'messages',
						action: 'read',
						query: { limit: 1, sort: '-date_created' },
					})
				);
			}
		</script>
	</body>
</html>

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Contributors
Kevin Lewis
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