#1,097 – Getting Items in Context Menu to Correctly Use Command Binding

Let’s say that you set up command bindings for a main Window in an application and then use the command for some control (e.g. a Button) and also within a ContextMenu.  (Assume that the GreetUser_CanExecute method always returns true).

    <Window.CommandBindings>
        <CommandBinding Command="{x:Static loc:MainWindow.GreetUserCommand}"
                        CanExecute="GreetUser_CanExecute"
                        Executed="GreetUser_Executed"/>
    </Window.CommandBindings>

    <Window.ContextMenu>
        <ContextMenu>
            <MenuItem Command="{x:Static loc:MainWindow.GreetUserCommand}"/>
        </ContextMenu>
    </Window.ContextMenu>

    <StackPanel>
        <TextBox Name="txtSomeText"
                 Width="220" Height="25" Margin="10"/>
        <Button HorizontalAlignment="Center"
                Padding="10,5" Margin="10"
                Content="{Binding RelativeSource={RelativeSource Self}, Path=Command.Text}"
                Command="{x:Static loc:MainWindow.GreetUserCommand}"/>
    </StackPanel>

If you run this code and right-click on the window to bring up the context menu, the MenuItem is greyed out.  It’s not binding correctly to our CanExecute method.  The Button, on the other hand, did find the binding.

1097-001

The fix for this is to set the CommandTarget for the MenuItem to the PlacementTarget of the parent ContextMenu–the Window.  The MenuItem definition becomes:

            <MenuItem Command="{x:Static loc:MainWindow.GreetUserCommand}"
                      CommandTarget="{Binding Path=PlacementTarget, RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"/>

1097-002

 

About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #1,097 – Getting Items in Context Menu to Correctly Use Command Binding

  1. Pingback: Dew Drop – June 19, 2014 (#1800) | Morning Dew

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: