Socket io group chat logic

[emirhanyagci]

I'm building a chat app and i'm comfused at some point how should be socket io logic these are my things please share if there is a more optimal option

1-) The new message events are emit for all user kinda like that

users.forEach((user) => {
      if (user._id == newMessageRecieve.sender._id) return;
      socket.in(user._id).emit('message recieved', newMessageRecieve);
});

2-) The other option is emiting to chatId but in this case i need add user to all existing chat.
I mean if user has 50 Conversation user should be in 50 different room

this is the situation i'm open the all advice.

[darrachequesne]

Hi!

You can take a look at our chat platform project. In this project, we use your 2nd option:

• the user join all the chat rooms it's part of:

  io.use(async (socket, next) => {
    // [...]

    let channels;

    try {
      channels = await db.fetchUserChannels(socket.userId);
    } catch (e) {
      return next(new Error("something went wrong"));
    }

    channels.forEach((channelId) => {
      socket.join(channelRoom(channelId));
    });

    // [...]

    next();
  });

Source: https://github.com/socketio/socket.io-chat-platform/blob/2a32486ff621a61648a3b28fad751e94a6cf2304/server/src/index.js#L92-L94

• then the message is simply sent to the chat room:

socket.broadcast
  .to(channelRoom(message.channelId))
  .emit("message:sent", message);

Source: https://github.com/socketio/socket.io-chat-platform/blob/2a32486ff621a61648a3b28fad751e94a6cf2304/server/src/message/send.js#L40-L42

[emirhanyagci]

thanks @darrachequesne then how should we optimize user rooms for example is it optimized for the user to be in 50 rooms at once maybe more maybe less actually i wonder why did you choose this way is there a reason ?

[darrachequesne]

The rooms the user is in are kept in memory, so you don't need to fetch them from the database every time a new message arrives.

[emirhanyagci]

thanks