How to create CommandBinding with a Parameter? - wpf

Question

Is there a way to create a CommandBinding with a parameter?
You can normally add bindings to commands for controls doing something like this:
<Control.CommandBindings>
<CommandBinding Command="ApplicationCommands.XXX" CanExecute="XXX_CanExecute"
Executed="XXX_Executed">
</CommandBinding>
</Control.CommandBindings>
I was wondering if there was also a way to pass a paramater?

Answer 1

No, you dont have a CommandParameter on the CommandBinding but you can use the InputBindings from UIElement to add for example a MouseBinding, which has a Command and CommandParameter attribute.
<Control>
<Control.InputBindings>
<MouseBinding MouseAction="LeftClick"
Command="{StaticResource MyCommand}"
CommandParameter="{x:Static system:Boolean.TrueString}"/>
</Control.InputBindings>
</Control>

Answer 2

You have to assign the parameter value to the ICommandSource.CommandParameter property of the element that invokes the command (for example Button.CommandParameter). This property also accepts a Binding.
You can retrieve the parameter from the ExecutedRoutedEventArgs.Parameter and CanExecuteRoutedEventArgs.Parameter property.
<Window>
<Window.CommandBindings>
<CommandBinding Command="ApplicationCommands.Delete"
CanExecute="DeleteCommand_CanExecute"
Executed="DeleteCommand_Executed" />
</Control.CommandBindings>
</Window.CommandBindings>
<Button Content="X"
Command="{x:Static ApplicationCommands.Delete}"
CommandParameter="abc" />
</Window>
private void DeleteCommand_Executed(object sender, ExecutedRoutedEventArgs e)
{
var commandParameter = e.Parameter as string; // Returns "abc"
}
private void DeleteCommand_CanExecute(object sender, CanExecuteRoutedEventArgs e)
{
var commandParameter = e.Parameter as string; // Returns "abc"
}
When clicking the Button or an ICommandSource in general, it sends the routed command along with the command parameter up the logical tree. The CommandBinding can catch this event and handle it using the registered handlers.
The point is that the command source must define the command parameter and not the CommandBinding. This way, the same CommandBinding can handle different command sources that send different command parameters.

Answer 3

Have you tried the CommandParameter property?
<DataGrid.ContextMenu>
<ContextMenu>
<MenuItem Header="MyHeader"
Command="{Binding MyCommand}"
CommandParameter="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}, Path=PlacementTarget.SelectedItem}" />
</DataGrid.ContextMenu>