oneTomany Relationship in Sproutcore

gistfile1.js

App.Category = SC.Record.extend({
    name: SC.Record.attr(String),
    parent: SC.Record.toOne('App.Category'),
    lft: SC.Record.attr(Number),
    rgt: SC.Record.attr(Number),
    itemType: SC.Record.attr(String),
    listings: SC.Record.toMany('App.Listing', {inverse: "category"}),

    //Tree Properties
    treeItemIsExpanded: NO,
    treeItemChildren: function(){
        return App.store.find(SC.Query.local(App.Category,
        "parent_id = {categoryId}", {
            categoryId: this.get('guid'),
            orderBy: "name ASC"
        }))
    }.property('guid').cacheable()
});

App.Listing = SC.Record.extend({
    title: SC.Record.attr(String),
    category: SC.Record.toOne("App.Category", {inverse: "listings"}),
    status: SC.Record.attr(Number),
    value: SC.Record.attr(String),
    type: SC.Record.attr(String),
    description: SC.Record.attr(String)
});


Csquare.Listing.FIXTURES = [

    {
        guid: 1,
        title: "The first of many posts",
        category: [10],
        description: "Another test of my Herculian Strength",
        type: "Sale",
        status: 2,
        value: 10
    }
]

Csquare.Category.FIXTURES = [

    {
        guid: 10,
        name: "For Sale",
        status: 2,
        lft: 0,
        rgt: 0,
        itemType: "sale",
        parent_id: 0
    }
]