define(["backbone", "jquery", "jquery.ui"], function(Backbone, $) {
    // course update -- biggest kludge here is the lack of a real id to map updates to originals
    var CourseUpdate = Backbone.Model.extend({
        defaults: {
            "date" : $.datepicker.formatDate('MM d, yy', new Date()),
            "content" : "",
            "push_notification_enabled": false,
            "push_notification_selected" : false
        },
        validate: function(attrs) {
            var date_exists = (attrs.date !== null && attrs.date !== "");
            var date_is_valid_string = ($.datepicker.formatDate('MM d, yy', new Date(attrs.date)) === attrs.date);
            if (!(date_exists && date_is_valid_string)) {
                return {"date_required": gettext("Action required: Enter a valid date.")};
            }
        }
    });
    return CourseUpdate;
}); // end define()