How to Bind CommandParameter to Unknown Parent

Question

I have the following context menu declared in my application resources, and it is referenced by several tree views in my app. I am trying to send the TreeView's SelectedItem property as the command parameter.

The problem is that I can't figure out how to get the commands to send the TreeView's SelectedItem.

The parameter is always null. I have tried using relative sources, templated parents, etc.; as well as, looking for a target of treeview, treeviewitem, and simply the datacontext. I have also tried sending different properties of these items (not just the TreeView's SelectedItem). I can't seem to get it to resolve anything.

<Application.Resources> <ContextMenu x:Key="ContextMenu.TreeView"> <MenuItem Header="Add Node" Command="{Binding AddNodeCommand}" CommandParameter="{Binding Path=SelectedItem, RelativeSource={RelativeSource AncestorType={x:Type TreeView}}}"></MenuItem> <MenuItem Header="Delete Node" Command="{Binding DeleteNodeCommand}" CommandParameter="{Binding Path=SelectedItem,RelativeSource={RelativeSource AncestorType={x:Type TreeView}}}"></MenuItem> </ContextMenu> </Application.Resources> <UserControl ...> <TreeView x:Name="TaxonomyTree" ItemsSource="{Binding Path=Tree}" ContextMenu="{StaticResource ContextMenu.TreeView}"/> </UserControl>

Viv · Accepted Answer · 2013-07-11 13:45:02Z

Try:

<ContextMenu x:Key="ContextMenu.TreeView"> <MenuItem Command="{Binding AddNodeCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=PlacementTarget.SelectedItem}" Header="Add Node" /> <MenuItem Command="{Binding DeleteNodeCommand}" CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=PlacementTarget.SelectedItem}" Header="Delete Node" /> </ContextMenu>

Contextmenu is not part of the same Visual tree as the TreeView it links against. So we need to use the PlacementTarget to route to the TreeView accordingly.

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