Does associated store supports filtering?

Does an associated store support filter and filterBy?

I'm dealing with a MainStore whose records have an associated store Products; I bind a list to Products of 1st record:

Code:

MyList.setStore(Ext.getStore('mainStore').getAt(0).Products())

I filter it to show only products whose name starts with 'F':

Code:

MyList.getStore().filterBy(function(item,id) {
return item.get("name").charAt(0).toUpperCase() === 'F';}

or the product named 'Foo':

Code:

MyList.getStore().filter('name', 'Foo');

None of them works.

They work only if:

1. The store is a normal "simple store", eg. loaded from a JSON - not nested or at the root "nesting level"


2. The store is created and filled at runtime, eg.:

Code:

var Products = Ext.create('Ext.data.Store', { storeId: 'productsStore', model: 'Myapp.model.Product'});

//... later in the controller
init: function() {
Ext.getStore('mainStore').on('load', function() {
this.getAt(0).Products().each(function(item, idx) {
Products.add(item.copy());
}
});}

This way it works, but I duplicated the store.

Am I missing something in the docs?

Thanks in advance

Question within the question:
Using .add(item) instead .add(item.copy()) does add a reference to the item, thus avoiding duplication?

It works anyway

Does associated store supports filtering?