Setting different styles for Dual level grouping with DataTrigger

Question

I have a dual level grouping and thought I could define different styles with DataTriggers.

Thinking that GroupStyles.HeaderTemplate would bind to CollectionViewGroup I tried DataBinding to IsBottomLevel property.

<GroupStyle>
     <GroupStyle.HeaderTemplate>
          <DataTemplate>
              <TextBlock x:Name="GroupName"
                         Text="{Binding Path=Name}"
                         Foreground="Red" />
                   <DataTemplate.Triggers>
                         <DataTrigger Binding="IsBottomLevel" Value="True" >
                              <Setter TargetName="GroupName" Property="Foreground" Value="Blue" />
                         </DataTrigger>
                    </DataTemplate.Triggers>
            </DataTemplate>
       </GroupStyle.HeaderTemplate>
  </GroupStyle>

Can I get this to work somehow?

Answer 1

Define your trigger in the Style of the TextBlock itself, TargetName normally is for ControlTemplates, then you can just drop that.

This is not a binding:

Binding="IsBottomLevel"

You should replace it with the following of course:

Binding="{Binding IsBottomLevel}"

---

<TextBlock Text="{Binding Name}">
    <TextBlock.Style>
        <Style TargetType="{x:Type TextBlock}">
            <Setter Property="Foreground" Value="Red" />
            <Style.Triggers>
                <DataTrigger Binding="{Binding IsBottomLevel}" Value="True">
                    <Setter Property="Foreground" Value="Blue" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBlock.Style>
</TextBlock>

If you set the red Foreground directly in the TextBlock declaration the trigger will have no effect due to precedence.