How to Automatically Use a DataTemplate Based on C

问题:

When I attempt to specify multiple DataTemplates for use by a ContentControl so that the correct one (based on Type) is used, I end up with Content that is simply the Content's ToString() value.

<ContentControl DataContext="{Binding MyTreeRootViewModels}" Content="{Binding /, Path=CurrentlySelectedTreeViewModel}">
  <ContentControl.Resources>
     <DataTemplate DataType="x:Type vm:TypeAViewModel">
        <StackPanel>
           <local:TypeAUserControl />
           </StackPanel>
     </DataTemplate>

     <DataTemplate DataType="x:Type vm:TypeBViewModel">
        <StackPanel>
           <local:TypeBUserControl />
        </StackPanel>
     </DataTemplate>
  </ContentControl.Resources>
</ContentControl>

In the example above I would see "MyApp.ViewModel.TypeAViewModel" displayed when a tree node of TypeAViewModel is returned by CurrentlySelectedTreeViewModel. I expect to see my TypeAViewModelUserControl.

I've tried putting a single <TextBlock Text="TESTING"/> element in one of my DataTemplates just to see if the problem was related to my user controls. Same result.

Any ideas what I am doing wrong?

(By the way, the CurrentlySelectedTreeViewModel is a property that returns the currently selected node in my treeview. It seems to work just fine - as I select nodes in the tree, the correct type name for the node appears ContentControl).

回答1:

The x:Type bit should be between curly braces {}:

<DataTemplate DataType="{x:Type vm:TypeAViewModel}">

回答2:

x:Type is a MarkupExtension, which requires {} to indicate to the XAML compiler.