CommandParameter with MVVM Light - wpf

Question

I'm trying to get a RelayCommand working with a CommandParameter working using MVVM Light. The command is defined in my viewmodel, and I want to pass the selected ListBox item as the parameter. The command is bound, but the parameter is not. Is this possible?
<UserControl x:Class="Nuggets.Metro.Views.EmployeeListView"
...
DataContext="{Binding EmployeeList,Source={StaticResource Locator}}">
<ListBox x:Name="lstEmployee" ItemsSource="{Binding EmployeeItems}" Style="{StaticResource EmployeeList}" Tag="{Binding EmployeeItems}">
<ListBox.ContextMenu>
<ContextMenu DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
<MenuItem Header="Edit item" Command="{Binding EditEmployeeCommand}" CommandParameter="{Binding PlacementTarget.SelectedItem,RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"/>
<MenuItem Header="Delete item" Command="{Binding DeleteEmployeeCommand}" CommandParameter="{Binding PlacementTarget.SelectedItem,RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"/>
</ContextMenu>
</ListBox.ContextMenu>

Answer 1

This should work
<ContextMenu DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
<MenuItem Header="Edit item"
Command="{Binding EditEmployeeCommand}"
CommandParameter="{Binding SelectedItem,ElementName=lstEmployee}"/>
<MenuItem Header="Delete item"
Command="{Binding DeleteEmployeeCommand}"
CommandParameter="{Binding SelectedItem,ElementName=lstEmployee}"/>
</ContextMenu>
Use the Name of your ListBox als ElementName in the binding of the CommandParameter and set the path to SelectedItem.
Update:
The above code does not work for ListBox and ContextMenu, cause they belong to diffrent visual trees. The result is
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=lstEmployee'. BindingExpression:Path=SelectedItem; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'CommandParameter' (type 'Object')
The following XAML does the job. Using the PlacementTarget (that is the ListBox) of the ContextMenu.
<ContextMenu DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
<MenuItem Header="Edit item"
Command="{Binding EditEmployeeCommand}"
CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.SelectedItem}"/>
<MenuItem Header="Delete item"
Command="{Binding DeleteEmployeeCommand}"
CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu}, Path=PlacementTarget.SelectedItem}"/>
</ContextMenu>

Answer 2

This works for TreeView or ListView with MVVM.
The PlacementTarget from the ContextMenu is (here) the Listview
<ListView.ContextMenu>
<ContextMenu>
<MenuItem x:Name="OpenExplorer"Header="ShowFolder"
Command="{Binding ShowExplorer}"
CommandParameter ="{Binding Path=PlacementTarget.SelectedItem,
RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
</ContextMenu>
</ListView.ContextMenu>