Thread Messages

Threads enable users to create a separate conversation from a specific message within a chat group to keep the main chat uncluttered.

This page shows how to use the Agora Chat SDK to send, receive, recall, and retrieve thread messages in your app.

Understand the tech

The Agora Chat SDK provides the ChatThreadManager, ChatMessage, and ChatThread classes for thread messages, which allows you to implement the following features:

• Send a thread message
• Receive a thread message
• Recall a thread message
• Retrieve a thread message

The following figure shows the workflow of how clients send and receive peer-to-peer messages.

As shown in the figure, the workflow of peer-to-peer messaging is as follows:

1. Clients retrieve a token from your app server.
2. Client A and Client B log in to Agora Chat.
3. Client A sends a message to Client B. The message is sent to the Agora Chat server and the server delivers the message to Client B. When Client B receives the message, the SDK triggers an event. Client B listens for the event and gets the message.

Prerequisites

Before proceeding, ensure that you meet the following requirements:

• You have initialized the Agora Chat SDK. For details, see Get Started with Flutter.
• You understand the call frequency limit of the Agora Chat APIs supported by different pricing plans as described in Limitations.

Implementation

This section describes how to call the APIs provided by the Agora Chat SDK to implement thread features.

Send a thread message

Sending a thread message is similar to sending a message in a chat group. The difference lies in the isChatThreadMessage field, as shown in the following code sample:

// Sets `targetGroup` to the ID of the chat group that receives the message.
// Sets `content` to the message content.
ChatMessage msg = ChatMessage.createTxtSendMessage(
  targetId: targetGroup,
  content: content,
);
// Sets `ChatType` to GroupChat as a thread that belongs to a chat group.
msg.chatType = ChatType.GroupChat;
// Sets `isChatThreadMessage` to `true` to mark this message as a thread message.
msg.isChatThreadMessage = true;
//  Sends the message.
ChatClient.getInstance.chatManager.sendMessage(msg);

For more information about sending a message, see Send Messages.

Receive a thread message

Once a thread has a new message, all chat group members receive the ChatThreadEventHandler#onChatThreadUpdated callback. Thread members can also listen for the ChatEventHandler#onMessagesReceived callback to receive thread messages, as shown in the following code sample:

  // Adds the chat event handler.
  ChatClient.getInstance.chatManager.addEventHandler(
    "UNIQUE_HANDLER_ID",
    ChatEventHandler(
      onMessagesReceived: (messages) {},
    ),
  );
  // Adds the thread event handler.
  ChatClient.getInstance.chatThreadManager.addEventHandler(
    "UNIQUE_HANDLER_ID",
    ChatThreadEventHandler(
      onChatThreadUpdate: (event) {},
    ),
  );
  ...
  // Removes the chat event handler.
  ChatClient.getInstance.chatManager.removeEventHandler("UNIQUE_HANDLER_ID");
  // Removes the chat thread event handler.
  ChatClient.getInstance.chatThreadManager.removeEventHandler("UNIQUE_HANDLER_ID");

For more information about receiving a message, see Receive Messages.

Recall a thread message

For details about how to recall a message, refer to Recall Messages.

Once a message is recalled in a thread, all chat group members receive the ChatThreadEventHandler#onChatThreadUpdated callback. Thread members can also listen for the ChatEventHandler#onMessagesRecalled callback, as shown in the following code sample:

  // Adds the chat event handler.
  ChatClient.getInstance.chatManager.addEventHandler(
    "UNIQUE_HANDLER_ID",
    ChatEventHandler(
      onMessagesRecalled: (messages) {},
    ),
  );
  // Adds the thread event handler.
  ChatClient.getInstance.chatThreadManager.addEventHandler(
    "UNIQUE_HANDLER_ID",
    ChatThreadEventHandler(
      onChatThreadUpdate: (event) {},
    ),
  );
  ...
  // Removes the chat event handler.
  ChatClient.getInstance.chatManager.removeEventHandler("UNIQUE_HANDLER_ID");
  // Removes the chat thread event handler.
  ChatClient.getInstance.chatThreadManager.removeEventHandler("UNIQUE_HANDLER_ID");

Retrieve thread messages from the server

For details about how to retrieve messages from the server, see Retrieve Conversations and Messages from Server.