Problems with hierarchical DataSource

[Roland]

Hi

I have problem with hierarchical data within the datasource. As a trivial example I have the following data:

var data = [{
    id: 1,
    firstName: "Alex",
    positions: [{
        address: {
            street: "somewhere"
        }
    }]
}];

in which the parent (firstName, id) should be shown inside a Grid and the Children (positions) inside the popup dialog. Now if I bind that it's not possible to show the street as a template #=address.street# 

How can I define a hierarchical DataSource and how can i define a hierarchical schema (to use the validation) 

Here I have a JSFiddle to reproduce my problem

Thanks in advance