Question

I’ve a custom SplitButton implementation in which contains a ComboBox with several ComboBoxItems bound to commands. I can bind to the Name, and Text properties of the command just fine but have no way of binding the ComboBoxItem’s IsEnabled property to the result of a Command’s CanExecute method because it is a method. Is there some syntax that I’m unaware of for binding to methods or is there some trickery that will help me to bind to CanExecute.

By the way, I’ve thought about using a custom ValueConverter except for that I realized that I probably wouldn’t receive any updates when CanExecute is re-evaluated since it is not a property and since my commands are not business objects. It’s looking to me that I might have to create a ViewModel for a command at this point to use only within my custom SplitButton control but that seems a little overboard to me.

Answer 1

Another solution by ViewModel. Below is how I used a ViewModel to solve my problem. And please note that the nifty NotifyPropertyChanged method is part of my base ViewModel class.

public class RoutedUICommandViewModel : ViewModel
{
    private RoutedUICommand _command;
    private IInputElement _target;

    public string Name { get { return _command.Name; } }

    public string Text { get { return _command.Text; } }

    public bool CanExecute
    {
        get
        {
            return _command.CanExecute(null, _target);
        }
    }

    public RoutedUICommand Command { get { return _command; } }

    public RoutedUICommandViewModel(ReportCommand command, IInputElement target)
    {
        _command = command;
        _target = target;
        _command.CanExecuteChanged += _command_CanExecuteChanged;
    }

    private void _command_CanExecuteChanged(object sender, EventArgs e)
    {
        base.NotifyPropertyChanged(() => this.CanExecute);
    }
}