Extended Silverlight AutoCompleteBox for Handling Enter and Command Binding

In our RIA Services application, we’re using the AutoCompleteBox control, but what if you want to select something from the list, press Enter and bind to a Command in a viewmodel? Sort of like the Button Command property.

I decided to extend the control and add a “Command” DependencyProperty for an ICommand which is executed when Enter is pressed and if an item is selected in the AutoCompleteBox. Works for us:

public class AutoCompleteBoxEx : AutoCompleteBox

{

    protected override void OnKeyDown(KeyEventArgs e)

    {

        if (SelectedItem != null && e.Key == Key.Enter)

        {

            if (Command != null)

                Command.Execute(SelectedItem);

        }

        base.OnKeyDown(e);

    }

    public static readonly DependencyProperty CommandProperty =

        DependencyProperty.RegisterAttached("Command",

                    typeof(ICommand),

                    typeof(AutoCompleteBoxEx),

                    null);

    public ICommand Command

    {

        get { return (ICommand)GetValue(CommandProperty); }

        set { SetValue(CommandProperty, value); }

    }

}