MVVM Madness: Commands

Question

I like MVVM. I don\'t love it, but like it. Most of it makes sense. But, I keep reading articles that encourage you to write a lot of code so that you can write XAML and don\'t

Answer 1

Although I prefer not to write code-behind when using the MVVM pattern, I think it's OK to do it as long as that code is purely related to the UI.

But this is not the case here : you're calling a view-model command from the code-behind, so it's not purely UI-related, and the relation between the view and the view-model command is not directly apparent in XAML.

I think you could easily do it in XAML, using attached command behavior. That way you can "bind" the MouseDoubleClick event to a command of your view-model :

   
      
   

    ...

You can also easily access the selected item of the ListView without referring to it directly, using the ICollectionView interface :

private ICommand _doSomething;

public ICommand DoSomething
{
    get
    {
        if (_doSomething == null)
        {
            _doSomething = new DelegateCommand(
                () =>
                {
                    ICollectionView view = CollectionViewSource.GetDefaultView(Items);
                    object selected = view.CurrentItem;
                    DoSomethingWithItem(selected);
                });
        }
        return _doSomething;
    }
}