WPF绑定中的父子关系

Question

I am working on an application which is totally based on MVVM. I am facing a binding problem.

<ListView ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}},Path=DataContext.CurrentSecurityList}">
<ListView.ContextMenu>
 <ContextMenu>
  <MenuItem Header="Remove" Command="{Binding RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type UserControl}},Path=DataContext.RemoveSecurity}"/>
 </ContextMenu>
</ListView.ContextMenu> 

ListView binding is working absolutely fine in this code but the problem comes when it comes to MenuItem Command Binding. Can someone explain what i am doing wrong over here.

Answer 1

ContextMenu works on different visual tree so it is not possible to bind it like that. You need to find ContextMenu ancestor and refer to its PlacementTarget.DataContext to retrieve your command. Try something like this:

<MenuItem Header="Remove" Command="{Binding RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type ContextMenu}},Path=PlacementTarget.DataContext.RemoveSecurity}"/>

Answer 2

Put a Tag in ListView to connect its ancestor to its ContextMenu:

<ListView ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}},Path=DataContext.CurrentSecurityList}"
              Tag="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}">
        <ListView.ContextMenu>
            <ContextMenu>
                <MenuItem Header="Remove" Command="{Binding PlacementTarget.Tag.DataContext.RemoveSecurity, RelativeSource={RelativeSource 
                                AncestorType=ContextMenu}}"/>
            </ContextMenu>
        </ListView.ContextMenu>
    </ListView>