Flex datagrid component and agregated classes

Answer 1

After some more tries got the problem solved.

<mx:DataGrid id="grid" dataProvider="{items}">
    <mx:columns>
        <mx:DataGridColumn headerText="aId">
            <mx:itemRenderer>
                <mx:Component>
                    <mx:Label text="{data.a.id}"/>
                </mx:Component>
            </mx:itemRenderer>
        </mx:DataGridColumn>
        <mx:DataGridColumn headerText="value" dataField="value"/>
    </mx:columns>
</mx:DataGrid>