WPF: binding MenuItem.CommandParameter to null

Question

I have the following ContextMenu defined for my data grid:

<igDP:XamDataGrid.ContextMenu>
    <ContextMenu ItemsSource="{Binding CommandViewModels}"                     >
        <ContextMenu.ItemContainerStyle>
            <Style TargetType="MenuItem">
                <Setter Property="Command" Value="{Binding Command}" />
                <Setter Property="CommandParameter" Value="{Binding CommandParameter}" />
                <Setter Property="Header" Value="{Binding Name}" />
                <Setter Property="Icon" Value="{Binding Icon}" />
            </Style>
        </ContextMenu.ItemContainerStyle>
    </ContextMenu>
</igDP:XamDataGrid.ContextMenu>

The CommandViewModel class is defined as follows:

public class CommandViewModel : ICommandViewModel
    {
        public CommandViewModel(string name, Image icon, ICommand command, object commandParameter = null, int index = 0)
        {
            Name = name;
            Icon = icon;
            Command = command;
            CommandParameter = commandParameter;
            Index = index;
        }

        public string Name { get; set; }
        public Image Icon { get; set; }
        public ICommand Command { get; set; }
        public object CommandParameter { get; set; }
        public int Index { get; set; }     
    }

When I right-click on a row in the grid, each MenuItem ContextMenu element is correctly decorated. The icon, label, and MenuItem command are as expected. However, the CommandViewModel.CommandParameter command parameter, which must be passed as the RelayCommand argument associated with MenuItem.Command, is null.

I'm pretty sure that the command parameter available for binding is not null. This is a WPF application running on .NET 4.0.

Has anyone experienced this?

Answer 1

, -, CommandParameter.

Prism, CommandParameterBehavior, CodePlex.

RelayCommand IDelegateCommand :

 public class RelayCommand : IDelegateCommand
{
    readonly protected Predicate<object> _canExecute;
    readonly protected Action<object> _execute;      

    public RelayCommand(Predicate<object> canExecute, Action<object> execute)
    {
        _canExecute = canExecute;
        _execute = execute;          
    }

    public void RaiseCanExecuteChanged()
    {
        if (CanExecuteChanged != null)
            CanExecuteChanged(this, EventArgs.Empty);
    }      

    public virtual bool CanExecute(object parameter)
    {
        return _canExecute(parameter);
    }

    public event EventHandler CanExecuteChanged;

    public virtual void Execute(object parameter)
    {
        _execute(parameter);
    }      
}

CommandParameterBehavior:

 <Style TargetType="MenuItem">
                <Setter Property="Command" Value="{Binding Command}" />
                <Setter Property="CommandParameter" Value="{Binding CommandParameter}" />
                <Setter Property="Header" Value="{Binding Name}" />
                <Setter Property="Icon" Value="{Binding Icon}" />
                <Setter Property="utility:CommandParameterBehavior.IsCommandRequeriedOnChange" Value="true"
            </Style>

CommandParameter .