Brothers In Code

I had a view model that consisted of a linked list of nodes.  I wanted to group one set of nodes so I decided to try out the grouping functionality of CollectionViewSource.

Here's my XAML:

    <HierarchicalDataTemplate x:Key="ActionNodeTemplate">
      <tool:ActionNavigatorActionNodeUC />
    </HierarchicalDataTemplate>    
    <HierarchicalDataTemplate x:Key="GroupTemplate" ItemsSource="{Binding Items}" ItemTemplate="{StaticResource ActionNodeTemplate}">
      <Label Foreground="Green" Content="{Binding Path=Name}" Name="NodeLabel"/>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate DataType="{x:Type an:ActionProjectSummaryNode}" ItemsSource="{Binding SubItemsView.View.Groups}" ItemTemplate="{StaticResource GroupTemplate}">
      <Label Foreground="Red" Content="{Binding Path=DisplayText}" Name="NodeLabel"/>
    </HierarchicalDataTemplate>
    <HierarchicalDataTemplate DataType="{x:Type an:RootActionNavigatorNode}" ItemsSource="{Binding SubItems}">
      <Label Foreground="Blue" Content="{Binding Path=DisplayText}" Name="NodeLabel"/>
    </HierarchicalDataTemplate>

ProjectActionSummaryNode exposed a CollectionViewSource of ActionNode items named SubItemsView.  In that node i grouped by the Data.ActionTypeDescription with:

       SubItemsView.GroupDescriptions.Clear();
       SubItemsView.GroupDescriptions.Add(new PropertyGroupDescription("Data.ActionTypeDescription"));

That was pretty much it.  For nodes of type ActionProjectSummaryNode, ItemsSource was set to SubItemsView.View.Groups.  Groups is a ReadOnlyObervableCollection of CollectionViewGroup objects (CollectionViewGroupInternal actually).  Each one has a Name property that represents the Group (in this case Data.ActionTypeDescription), and a Items Property that contains the original items that were grouped (ActionNodes).