Htykuut

Environment

socket.io 2.1.1 

express 4.16.3  

Node v10.13.0  

Desired Behaviour

When a client joins a room, all clients in the room receive a list of all clients in the room, including each client's custom socket.username property.

What I've Tried

Attempt 01:

Use the clients() method with a callback, see:

https://socket.io/docs/server-api/#namespace-clients-callback.

socket.on('join', function(data) {

    // get desired room name

    var room = data.room;

    // get username

    var username = data.username;

    // add username key:value to socket

    socket.username = username;

    // add socket to room

    socket.join(room);



    // get list of clients in room

    io.of('/').in(room).clients((error, clients) => {

        if (error) {

            throw error;

        } else {

            // send data to all clients in room

            io.in(room).emit('room_join', { username: socket.username, room: room, clients: clients });

        }

    });

});

In the above example, clients is returned as an array of socket id's.

Attempt 02:

Use io.sockets.adapter.rooms[room], inspired by this answer:

socket.on('join', function(data) {

    var room = data.room;

    var username = data.username;

    socket.username = username;

    socket.join(room);

    var sockets_in_room = io.sockets.adapter.rooms[room];

    io.in(room).emit('room_join', { username: socket.username, room: room, sockets_in_room: sockets_in_room });

});

The above returns:

Room { sockets: { '3-fHYqg7e8h-6K8EAAAC': true }, length: 1 }

Question

It seems a custom username property can be added to a socket with:

socket.username= "john";

How can that property be accessible in a list of "client objects" so that the usernames of all clients in a room are accessible?

Edit 1

In case it is relevant, there are possibly thousands of rooms in this scenario, with each room name derived from a unique content id, so any solutions need to accommodate that constraint.

Edit 2

I made the following and it seems to be working, not sure if heading in right direction or not:

var users_in_rooms = {};



io.on('connection', function(socket) {



    // handle joining

    socket.on('join', function(data) {

        var room = data.room;

        var username = data.username;

        socket.username = username;

        socket.join(room);

        // add key:value to users_in_rooms object

        users_in_rooms[socket.id] = username; 



        // get list of clients in room

        io.of('/').in(room).clients((error, clients) => {

            if (error) {

                throw error;

            } else {

                // for each socket id in the clients array, look up its corresponding username

                var client_object_array = clients.map(socketid => ({

                    socketid: socketid,

                    username: users_in_rooms[socketid]

                }));

                // return client_object_array to all clients

                io.in(room).emit('room_join', { client_object_array: client_object_array, username: socket.username, room: room  });

            }

        });

    });



    // handle leaving

    socket.on('leave_all', function() {

        socket.leaveAll();

        // when a user leaves all rooms, delete their corresponding entry from the users_in_rooms object

        delete users_in_rooms[socket.id];

    });



    // handle disconnecting

    socket.on('disconnect', function(reason) {

        console.log("client " + socket.id + " disconnected because:");

        console.log(reason);

        delete users_in_rooms[socket.id];

    });



});