[Moo] populating class variables within a request onSuccess

[drew n]

The following code requests information about an object, and then
tries to set a couple class variables based on the data returned from
the request.

var Demo = new Class({
    save: function() {
            var req = new Request.JSON({
                url: "/demos.json",
                method: "post",
                data: {"demo[name]":this.name,
"authenticity_token":this.auth_token},
                onSuccess: function(d) {
                    this.updateDemo(d.demo.id, d.demo.name);
                    this.id = d.demo.id;
                }.bind(this)
            }).send();
    },

    updateDemo: function(id, name) {
        this.id = id;
        this.name = name;
    }
}

I've got "this" binded properly because I can access the updateDemo
function properly but I can't seem to be able to set variables from
within the updateDemo function, or the onSuccess function.

If I create a demo class and then try and access the "id" variable, it
returns as undefined. What am I doing wrong?

Thanks in advance!