Parse.com unable to output proper JSON

Let's say I have two Classes (tables) in Parse:

--- TABLE 1: Navigation -------------------
objectId
Name
Url
-------------------------------------------

--- TABLE 2: Items ------------------------
objectId
Navigation (pointer to Navigation class)
Name
Price
-------------------------------------------

All I want is for some JSON output like the following:

[
{
name: "Home",
url: "home"
},
{
name: "Menu",
url: "menu",
items: [{
    name: "French Fries",
    price: 3.00
    },
    {
    name: "Hamburger",
    price: 4.00
    },
    {
    name: "Cheeseburger",
    price: 5.00
    }]
},
{
name: "Dinner Menu",
url: "dinner-menu",
items: [{
    name: "Beer",
    price: 3.00
    },
    {
    name: "Wine (glass)",
    price: 9.00
    },
    {
    name: "Liquor Premium",
    price: 8.00
    }]
},
{
name: "Like and Follow Us",
url: "social-media"
}
]

I have tried everything in my power to make a query with a nest query inside that to loop the items. I have tried looking at the documentation for Parse.Promises, which I believe to be part of the problem, and cannot get the results to appear like above. Help!!!

My broken code:

var mainNav = [];
var navigationQuery = new Parse.Query(Parse.Object.extend("Navigation"));
navigationQuery.ascending("SortOrder").find().then(function(navItems) {

    _.each(navItems, function(navItem) {

        var newObj = {};
        newObj.Name = navItem.get("Name");
        newObj.Url = navItem.get("Url");
        newObj.Module = navItem.get("Module");
        newObj.SortOrder = navItem.get("SortOrder");

        var itemQuery = new Parse.Query(Parse.Object.extend("ListItems")).equalTo('Navigation', navItem).ascending('SortOrder').find(function(items) {
            newObj.Source = items; // not getting added to object!
        });
        mainNav.push(newObj);

    });


}).then(function(items) {

    res.send(mainNav);

});