Change field type on POST/PUT for Restful table

I’m trying to figure out how to change the type submitted by a Restful table’s POST and PUTs from the default string to some other type (like a number).

E.g. With the following table how would I get the POSTed JSON to actually have the “num” field be a number?

new AJS.RestfulTable({
        el: jQuery("#test-table"),
        autoFocus: true,
        resources: {
            all: "/test",
            self: "/test"
        columns: [
                id: "id",
                header: "ID",
                allowEdit: false,
                id: "name",
                header: "Name"
                id: "num",
                header: "Num",
                createView: AJS.RestfulTable.CustomCreateView.extend({
                    render: function ( self ) {
                        var $field = $("<input type='number' id='num' name='num'></input>");
                        return $field;