Support replies in your app built with XMTP

Use the reply content type to support quote replies in your app. A reply is a method to directly respond to a specific message in a conversation. Users can select and reply to a particular message instead of sending a new one.

Open for feedback

You're welcome to provide feedback by commenting on the Proposal for Reply content type XIP idea.

Use a local database for performance

Use a local database to store replies. This will enable your app to performantly display a reply with its referenced message when rendering message lists.

To learn more about using a local database, see Use local-first architecture.

Configure the content type

In some SDKs, the ReplyCodec is already included in the SDK. If not, you can install the package using the following command:

JavaScript

In the JavaScript SDK, you need to import this package first.

npm i @xmtp/content-type-reply

After importing the package, you can register the codec.

import { ContentTypeReply, ReplyCodec } from "@xmtp/content-type-reply";
// Create the XMTP client
const xmtp = await Client.create(signer, { env: "dev" });
xmtp.registerCodec(new ReplyCodec());

React

The React SDK supports all current standards-track content types, but only text messages are enabled out of the box. Adding support for other standards-track content types requires a bit of configuration.

import {
  XMTPProvider,
  replyContentTypeConfig,
} from "@xmtp/react-sdk";

const contentTypeConfigs = [
  replyContentTypeConfig,
];

createRoot(document.getElementById("root") as HTMLElement).render(
  <StrictMode>
    <XMTPProvider contentTypeConfigs={contentTypeConfigs}>
      <App />
    </XMTPProvider>
  </StrictMode>,
);

Kotlin

import org.xmtp.android.library.codecs.ReplyCodec

Client.register(codec = ReplyCodec())

Swift

Client.register(codec: ReplyCodec())

Dart

import 'package:xmtp/src/content/codec_registry.dart';
import 'package:xmtp/src/content/decoded.dart';
import 'package:xmtp/src/content/text_codec.dart';
import 'package:xmtp/src/content/reply_codec.dart';

// Registering
var registry = CodecRegistry()..registerCodec(TextCodec());
var codec = ReplyCodec();
codec.setRegistry(registry);;

React Native

const client = await Client.create(signer, {
  env: "production",
  codecs: [new ReplyCodec()],
});

Send a reply

Once you've created a reply, you can send it. Replies are represented as objects with two keys:

• reference: ID of the message being replied to

• content: String representation of the reply

JavaScript

import { ContentTypeText } from "@xmtp/content-type-text";
import { ContentTypeReply } from "@xmtp/content-type-reply";
import type { Reply } from "@xmtp/content-type-reply";

const reply: Reply = {
  reference: someMessageID,
  contentType: ContentTypeText
  content: "I concur",
};

await conversation.send(reply, {
  contentType: ContentTypeReply,
});

React

import { useSendMessage } from "@xmtp/react-sdk";
import { ContentTypeReply } from "@xmtp/content-type-reply";

const { sendMessage } = useSendMessage();

const replyContent = {
  content: "Your reply content here",
  contentType: ContentTypeText,
  reference: "originalMessageXmtpId",
};

sendMessage(conversation, replyContent, ContentTypeReply);

Kotlin

import org.xmtp.android.library.codecs.ContentTypeReply
import org.xmtp.android.library.codecs.ContentTypeText
import org.xmtp.android.library.codecs.Reply

// Assuming aliceConversation and messageToReact are already defined
val reply = Reply(
    reference = messageToReact.id,
    content = "Hello",
    contentType = ContentTypeText
)

aliceConversation.send(
    content = reply,
    options = SendOptions(contentType = ContentTypeReply),
)

Swift

let reply = Reply(
  reference: messageToReply.id,
  content: "Hello",
  contentType: ContentTypeText
)

try await conversation.send(
  content: reply,
  options: .init(contentType: ContentTypeReply)
)

Dart

import 'package:xmtp/src/content/codec_registry.dart';
import 'package:xmtp/src/content/decoded.dart';
import 'package:xmtp/src/content/text_codec.dart';
import 'package:xmtp/src/content/reply_codec.dart';

var parentMessageId = "abc123"; // The ID of the message you're replying to
var replyContent = DecodedContent(contentTypeText, "This is my reply"); // The content of your reply

// Create a Reply instance
var reply = Reply(parentMessageId, replyContent);

// Send the reply
await client.sendMessage(conversation, reply, contentType: contentTypeReply);

React Native

// Assuming you have a conversation object and the ID of the message you're replying to
const replyContent = {
  reply: {
    reference: messageId, // ID of the message you're replying to
    content: {
      text: "This is a reply", // Content of the reply
    },
  },
};

await conversation.send(replyContent);

Receive the content type

JavaScript

if (message.contentType.sameAs(ContentTypeReply)) {
  // We've got a reply.
  const reply: Reply = message.content;
}

React

import { ContentTypeId } from "@xmtp/react-sdk";
import { ContentTypeReply } from "@xmtp/content-type-reply";

const contentType = ContentTypeId.fromString(message.contentType);

if (ContentTypeReply.sameAs(contentType)) {
  // We've got a reply.
  const reply = message.content as Reply;
  // Use reply...
}

getReplies

Use to retrieve all replies for a given message. It takes a message object and returns an array of reply IDs.

import { getReplies } from "@xmtp/react-sdk";
const replies = getReplies(message);

hasReply

Use to check if a given message has any replies. It takes a message object and returns a boolean indicating whether the message has replies.

import { hasReply } from "@xmtp/react-sdk";
const messageHasReply = hasReply(message);

getOriginalMessageFromReply

Use to retrieve the original message the reply is responding to. It takes a reply message object and returns the original message object.

import { getOriginalMessageFromReply } from "@xmtp/react-sdk";
const originalMessage = await getOriginalMessageFromReply(replyMessage, db);

Kotlin

if (encodedContent.type == ContentTypeReply) {
    // The message is a reply
    val reply: Reply? = message.content()
    println("Reply to: ${reply?.reference}")
    println("Content: ${reply?.content}")
}

Swift

let content: Reply = try message.content()

Dart

var decodedContent = await registry.decode(encoded);
if (decodedContent.contentType == contentTypeReply) {
  // The message is a reply.
}

React Native

if (message.contentTypeId === "xmtp.org/reply:1.0") {
  const reply = message.content();
  if (reply) {
    const replyContent: ReplyContent = reply;
    const replyContentType = replyContent.contentType;
    const codec = client.codecRegistry[replyContentType];
    const actualReplyContent = codec.decode(replyContent.content);
  }
}

To handle unsupported content types, refer to the fallback section.

Display the reply

How you choose to display replies in your app is up to you. It might be useful to look at the user experience for replies in popular apps such as Telegram and Discord. For example, in Discord, users can reply to individual messages, and the reply provides a link to the original message.

Note that the user experience of replies in iMessage and Slack follows more of a threaded pattern, where messages display in logical groupings, or threads. This reply content type doesn't support the threaded pattern. If you'd like to request support for a threaded reply pattern, post an XIP idea.