MVVM datatemplate 下button.contextmenu的command 失效解决方案

 1 <Button CommandParameter="{Binding}"
 2 Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type pagesView:OutputPage}}}"
 3 Command = "{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type pagesView:OutputPage}}, Path=DataContext.EditOutputCommand}">
 4 <Button.ContextMenu>
 5 <ContextMenu>
 6 <MenuItem Header="削除" 
 7 CommandParameter="{Binding}"
 8 Command="{Binding Path=PlacementTarget.Tag.DataContext.DeleteCurrentLineCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ContextMenu}}"/>
 9 </ContextMenu>
10 </Button.ContextMenu>
11 </Button>