SignalR - Send message OnConnected

Mittchel picture Mittchel · May 21, 2015 · Viewed 22.9k times · Source

I've been experimenting with SignalR today and It's really neat. Basically what I wanted to achieve is the following:

As soon as a device connects it should send a message to the first one. If there are more devices than 1 connected I would like to send two messages. One to all except the last connected client. And one message to only the last connected client.

The code I've been using works perfect when I place it in a custom API controller and basically call the action, but that's not what I want.

I would like to send the messages as soon as a device connects within OnConnected without any user interaction, but when I place my code inside the OnConnected override it stops working. It doesn't send to the specific clients anymore (first connected and last connected).

I hope someone is able to help me out with this, because I've been banging my head for a few hours now.

    public override System.Threading.Tasks.Task OnConnected()
    {
        UserHandler.ConnectedIds.Add(Context.ConnectionId, UserHandler.ConnectedIds.Count + 1);

        int amountOfConnections = UserHandler.ConnectedIds.Count;
        var lastConnection = UserHandler.ConnectedIds.OrderBy(x => x.Value).LastOrDefault();
        var allExceptLast = UserHandler.ConnectedIds.Take(amountOfConnections - 1).Select(x => x.Key).ToList();

        if (amountOfConnections == 1)
        {
            Clients.Client(UserHandler.ConnectedIds.First().Key).hello("Send to only(also first) one");
        }
        else
        {
            Clients.Clients(allExceptLast).hello("Send to everyone except last");
            Clients.Client(lastConnection.Key).hello("Send to only the last one");
        }

        return base.OnConnected();
    }

Answer

Wasp picture Wasp · May 21, 2015

Unless I miss something from your question, the solution looks pretty simple to me, you just need to switch to using

Clients.Caller.hello("Send to only the last one");

instead of trying to understand yourself who's the last connected id. Same for the other ones, you can use:

Clients.Others.hello("Send to everyone except last");

You do not need all the logic you setup, those 2 lines do what you need, and they work inside OnConnected.