Creating hasMany associations in Sencha Touch 2

I'm trying to create a simple model association in Sencha Touch 2.3.1.

Basically I want to have a store of coupons, arranged in categories. So every category hasMany coupons.

My data is currently hardcoded in the store declarations (no proxy or server).



Category model declaration :

Code:

Ext.define('Category', {
    extend: 'Ext.data.Model',
    requires:['Ext.data.Model'],
    config: {
        idProperty: 'id',
        fields: [
            { name: 'id'},
            { name: 'name' },
            { name: 'itemType'}
        ],
        hasMany: [
            {
                associatedModel: 'Coupon',
                name: 'Coupons',
                foreignKey: 'category_id'
            }
        ]
    }
});

Coupon model :

Code:

Ext.define('Coupon', {
    extend: 'Ext.data.Model',
    config: {


        fields: [
            { name: 'couponId'},
            { name: 'title'},
            { name: 'description'},
            { name: 'category_id'},
        ],
        belongsTo: [
            {
                model: 'Category',
                name: 'Category',
                associationKey: 'category_id'
            }
        ]
    }
});

Category store and data:

Code:

Ext.define('CategoryStore', {
    extend: 'Ext.data.Store',


    config: {
        autoLoad: true,


        data: [
            {
                id: 1,
                name: "cat1"
            },
            {
                id: 2,
                name: "cat2"
            }
        ],
        model: 'Category',
        storeId: 'CategoryStore'
    }
});

Coupon Store :

Code:

Ext.define('CouponStore', {    extend: 'Ext.data.Store',
    config: {
        autoLoad: true,


        data: [
            {
                id: '1',
                title: 'coupon1',
                description : 'some desc',
                category_id:1
            },
            {
                id: '2',
                title: 'coupon2',
                description : 'desc2',
                category_id:2
            }
        ],
        model: 'Coupon',
        storeId: 'CouponStore'
    }
});

And finally, the code in the launch function in app.js :

Code:

Ext.application({
    name: 'hasmany',


    launch: function () {
        // Destroy the #appLoadingIndicator element
        Ext.fly('appLoadingIndicator').destroy();


       var categoryStore = Ext.create('CategoryStore');
       var cat2 = categoryStore.findRecord('name','cat2');


       console.log(cat2.getData()); //This works fine


   console.log(cat2.Coupons().getData()); //This returns an empty array
    }
});

The Results : The hasMany association method cat2.Coupons() returns an empty array :

Chrome console :

Code:

> Object {id: 2, name: "cat2", itemType: undefined} app.js:100
Class {all: Array[0], items: Array[0], keys: Array[0], indices: Object, map: Object…}

Any help would be appreciated, thanks !



*** EDIT : I managed to achieve the desired results using a manual filter:

Code:

var couponStore = Ext.create('CouponStore');
couponStore.filter('category_id',2);

So that's good enough for me at the moment, however I would be very interested to know why my previous code didn't work.