CODEWITHSUNDEEP
javascriptc#asp.netwebformssignalr
Daniel Anderson
Daniel Anderson

Reputation: 275

Javascript call to a SignalR hub method doesn't return a value

I am writing a chat room page for my web site, and I've run into a bit of a snag. I want to be sure that the names being used by chat room participants are unique. The hub class itself contains a List<> of participants already taking part in the chat, so I added a method to the class to check for the existence of a name already in use:

    public bool UserNameInUse(string name)
    {
        UserDetail item = ConnectedUsers.FirstOrDefault(x => x.UserName == name);
        return (item.ConnectionId == null);
    }

On the Javascript side, I am trying to call the hub method to check if the name is already in use before starting the connection, like so:

   $("#btnStartChat").click(function () {

    var name = $("#txtNickName").val();
    if (name.length > 0) {
        var status = chatHub.server.userNameInUse(name);
        alert(status);
        if (status!=1)
            chatHub.server.connect(name);
        else
            alert("The name you chose is already in use.  Try a different one, please.");
    }
    else {
        alert("Please enter a name to use for this chat.");
    }
});

As you can see, I instrumented the call to see what was being returned. But rather than obtaining a value from the hub method call (which does fire, since I tested it in Visual Studio under debug mode), this is what I get from the alert box:

screenshot of what the call returns

I've tried changing the return type to a string and sending back text, to an int and returning a number, yet I get the same result every time when I run the code. Can anyone help me understand why the call doesn't return a value?

Upvotes: 1

Views: 1847

Answers (1)

David Naylor
David Naylor

Reputation: 116

You need to register callback functions to receive the server response e.g.

chatHub.server.UserNameInUse(name).done(function (isInUse) {
    if (isInUse) {
       // Server returned true
    } else {
       // Server returned false
    }
}).fail(function (error) {
    console.log('Invocation of UserNameInUsefailed. Error: ' + error);
});

For more info check out the SignalR docs here

How to call server methods from the client

Upvotes: 2

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