How do I specify a HierarchicalDataTemplate for a templated type?

Sometimes you might have to specify a HierarchicalDataTemplate for a templated type. If so, you can only do this in code-behind. (If you have to do this in XAML try wrapping that template type within a non-templated dummy type.)

For example, if you have to do something like this:

            <HierarchicalDataTemplate ItemsSource='{Binding}'  
                                      DataType='{x:Type local:MyTemplatedList<int>}'>   
                <TextBlock Text='{Binding Name}'></TextBlock>  
            </HierarchicalDataTemplate>  

The above wouldn’t compile because the XAML compiler doesn’t support this.

So, you will have to do this in code-behind instead:

using MyListType = MyTemplatedList;

// Then in Window’s constructor for example:
HierarchicalDataTemplate hdt = new HierarchicalDataTemplate(typeof(MyListType));   
hdt.ItemsSource = new Binding();   
FrameworkElementFactory tb = new FrameworkElementFactory(typeof(TextBlock));   
tb.SetBinding(TextBlock.TextProperty, new Binding('Name'));   
hdt.VisualTree = tb;   
this.Resources[new DataTemplateKey(typeof(CountryList))] = hdt;  

Note that the above code also illustrates how to add a HierarchicalDataTemplate resource to the Resources list without specifying a key.