WPF HiercharchicalDataTemplate.DataType: How to react on interfaces?

Question

Problem

I\'ve got a collection of IThings and I\'d like to create a HierarchicalDataTemplate for a TreeView. The straightfor

Answer 1

The reason for this is that the default template selector supports only concrete types, not interfaces. You need to create a custom DataTemplateSelector and apply it to the ItemTemplateSelector property of the TreeView. I can't find the URL where I found an example of it, but hopefully with this info, you can Google it.

Answer 2

Another solution is you give a key to the HierarchicalDataTemplate and put it in the Windows.Resources, and manually reference to it in the TreeView. <TreeView ItemDataTemplate={StaticResource templateKey}/>

But that limits the autoselection of data template according to data type, which is provided by WPF TreeView.

Answer 3

Another alternative (similar to jing's solution): If you only have one type of item, you can set the ItemTemplate directly. Then you don't need to set a key or a datatype.

In your ViewModel:

public ObservableCollection<IThing> Thingies { get; private set; }

In the View:

<TreeView ItemsSource="{Binding Thingies}">
    <TreeView.ItemTemplate>
        <HierarchicalDataTemplate ItemsSource="{Binding SomeThings}">
            <TextBox Text="{Binding SomeString}" />    
        </HierarchicalDataTemplate>
    </TreeView.ItemTemplate>
</TreeView>