Question

I want to bind a command in my ViewModel to a menuItem which is in DataTemplate. I can do that with using Tag. Is there any method which can do the same task but without using tag.

<Window.Resources>
    <DataTemplate x:Key="StudentListBoxItemTemplate">
        <StackPanel Tag="{Binding DataContext, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListBox}}}">
            <TextBlock Text="{Binding Name}"/>
            <StackPanel.ContextMenu>
                <ContextMenu>
                    <MenuItem Header="Trigger" Command="{Binding PlacementTarget.Tag.TriggerCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
                </ContextMenu>
            </StackPanel.ContextMenu>
        </StackPanel>
    </DataTemplate>
</Window.Resources>
<StackPanel>
    <ListBox 
        ItemsSource="{Binding StudentList}" 
        ItemTemplate="{StaticResource StudentListBoxItemTemplate}">
    </ListBox>
</StackPanel>

My ViewModel

public class MainViewModel {
    public ICommand TriggerCommand { ... }
    public ObservableList<Student> StudentList { ... }
}

Answer 1

With your current design, you need to get from the ContextMenu through the StackPanel and back to the DataContext of the containing ListBox. What makes this awkward is that the DataContext of the StackPanel is already narrowed down to a particular student.

There are at least two ways to make this easier:

• Provide a TriggerCommand property in Student so the command is right there where you need it
• Provide a Parent property in the Student to escape the narrowed scope