Video SDK usePubSub Hook - React

usePubSub Hook

usePubSub takes all the properties and events as parameters and returns all the properties and methods to work pubsub instance.

usePubSub example

usePubSub react hook

import { usePubSub } from "@videosdk.live/react-sdk";

var topic = "CHAT";

function onMessageReceived(message) {
  console.log("New Message:", message);
}

function onOldMessagesReceived(messages) {
  console.log("Old Messages:", messages);
}

const { publish, messages } = usePubSub(topic, {
  onMessageReceived,
  onOldMessagesReceived,
});

Parameters

topic

• type : String

• Represents the topic for which you are publishing and getting a message.

---

onMessageReceived

• onMessageReceived() will be triggered when a new message is published for the subscribed topic with the message object.

---

onOldMessagesReceived

• onOldMessagesReceived() will be triggered once when you subscribe to the topic and will receive all the old messages present for that topic as an array of message object.

• message published with persist as true will only be available through this callback.

---

Returns

publish()

• publish() is used to publish the the message for the the particular topic.

Parameters

message

• type : String

• Message that has been published on the specific topic.

---

options

• type : Object

• This specifies the options for publish. You can specify following properties.

  • persist: When persist is set to true, that message will be retained for upcoming participants.
  • sendOnly: If you want to send a message to specific participants, you can pass their respective participantId here. If you don't provide any IDs, the message will be sent to all participants by default.

---

payload

• type : Object

• If you need to include additional information along with a message, you can pass here.

---

Example

const { publish, messages } = usePubSub("CHAT");

const sendMessage = (message) => {
  publish(message, { persist: true }, null, null);
};

sendMessage("Hello");

---

messages

• messages is an array of message objects which will hold all the persisted messages.

Message Object

{
  id: String,
  message: String,
  senderId: String,
  senderName: String,
  timestamp: String,
  topic: String,
  payload: Object
}