Question

I have two classes, which reference the third:

class Data1
{
   public Named Xxx { get; set; }
   public SomeClass1 Foo { get; set; }
   ...
}

class Data2
{
   public Named Yyy { get; set; }
   public SomeClass2 Bar { get; set; }
   ...
}

class Named
{
   public string Name { get; set; }
   ...
}

Now, I would like to display both Data1 & Data2:

<TreeView DataContext={Binding Path=Data1}>
  <TreeView.Items>
    <TreeViewItem>
      <TreeViewItem.Header>
        <StackPanel Orientation="Horizontal">
          <ContentControl xml:space="preserve">Name: </ContentControl>
          <ContentControl Content="{Binding Path=Xxx.Name}" />
        </StackPanel>
      </TreeViewItem.Header>
    </TreeViewItem>
    <TreeViewItem><!-- somehow display Foo --></TreeViewItem>
    <!-- More TreeViewItems, specific to Data1 -->
  </TreeView.Items>
</TreeView>

<TreeView DataContext={Binding Path=Data2}>
  <TreeView.Items>
    <TreeViewItem>
      <TreeViewItem.Header>
        <StackPanel Orientation="Horizontal">
          <ContentControl xml:space="preserve">Name: </ContentControl>
          <ContentControl Content="{Binding Path=Yyy.Name}" />
        </StackPanel>
      </TreeViewItem.Header>
    </TreeViewItem>
    <TreeViewItem><!-- somehow display Bar --></TreeViewItem>
    <!-- More TreeViewItems, specific to Data2 -->
  </TreeView.Items>
</TreeView>

So, markup is different, except for TreeViewItem that displays Named class. I would like to reuse markup for this TreeViewItem. It is too simple to make UserControl of it, but it is still a little more complicated than shown in example. So, I would really like to do something like this:

<ResourceDictionary>
  <TreeViewItem x:Key="Named">
    <TreeViewItem.Header>
      <StackPanel Orientation="Horizontal">
        <ContentControl xml:space="preserve">Name: </ContentControl>
        <ContentControl Content="{Binding Path=Name}" />
      </StackPanel>
    </TreeViewItem.Header>
  </TreeViewItem>
</ResourceDictionary>

And then just use it like this:

<TreeView DataContext={Binding Path=Data1}>
  <TreeView.Items>
    <StaticResource ResourceKey="Named" />
  </TreeView.Items>
</TreeView>

As you can see, Data1‘s property name for Named is Xxx, while Data2‘s property name for Named is Yyy. So, I have to pass that somehow to my resource. But how?

E.g. how do I set the DataContext of this StaticResource subtree to Xxx for Data1?

Something like this doesn’t work:

    <StaticResource ResourceKey="Named" DataContext={Binding Path=Xxx} />

Sorry for the long question.

Edit:

All I want is a piece of XAML, capable of displaying a Named instance. So, I want to be able to specify where to get the instance (from Xxx or Yyy) outside of this piece, so I can reuse it.

Edit2: here is the solution with ControlTemplate, however it doesn’t work well: the TreeViewItem becomes unselectable. What’s wrong?

<ControlTemplate x:Key="Named" TargetType="TreeViewItem">
    <TreeViewItem>
        <TreeViewItem.Header>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="Name: " />
                <TextBlock Text="{Binding Path=Name}" />
            </StackPanel>
        </TreeViewItem.Header>
    </TreeViewItem>
</ControlTemplate>

<!-- now use the template: -->
<TreeView>
  <TreeView.Items>
    <TreeViewItem Template="{StaticResource Named}" 
                  DataContext="{Binding Path=Xxx}" />
    ...

Answer 1

OK, I took a nap today and when I woke up, I suddenly realized what the answer is! Here it is:

<!-- In resources: -->
<Style TargetType="TreeViewItem" x:Key="Named">
  <Setter Property="Header" Value="{Binding Name}" />
  <Setter Property="HeaderTemplate">
    <Setter.Value>
      <DataTemplate>
        <StackPanel Orientation="Horizontal">
          <TextBlock Text="Name: " />
          <TextBlock Text="{Binding}" />
        </StackPanel>
      </DataTemplate>
    </Setter.Value>
  </Setter>
</Style>

<!-- now use the template: -->
<TreeView>
  <TreeView.Items>
    <TreeViewItem Style="{StaticResource Named}" 
                  DataContext="{Binding Path=Xxx}" />
    ...