WPF - Close window from UserControl ViewModel when using ViewModelLocator pattern

Question

I have a WPF app in which I use Windows to house UserControls which contain all the actual controls and whose ViewModels do all the actual work. In other words the Windows don't do anything besides be a graphical container for my UserControls (I believe this is a good practice?). I am marrying the views and viewmodels by use of the ViewModelLocator pattern, shown below:

namespace Frontend
{
    /// <summary>
    /// Locates and "marries" views to their corresponding viewmodels,
    /// provided they follow the standard naming convention.
    /// </summary>
    public static class ViewModelLocator
    {
        public static bool GetAutoWireViewModel(DependencyObject obj)
        {
            return (bool)obj.GetValue(AutoWireViewModelProperty);
        }

        public static void SetAutoWireViewModel(DependencyObject obj, bool value)
        {
            obj.SetValue(AutoWireViewModelProperty, value);
        }

        // Using a DependencyProperty as the backing store for AutoWireViewModel.  This enables animation, styling, binding, etc...
        public static readonly DependencyProperty AutoWireViewModelProperty =
            DependencyProperty.RegisterAttached("AutoWireViewModel", typeof(bool), typeof(ViewModelLocator), new PropertyMetadata(false, AutoWireViewModelChanged));

        private static void AutoWireViewModelChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            if (DesignerProperties.GetIsInDesignMode(d)) return;
            var viewType = d.GetType();
            var viewTypeName = viewType.FullName;
            var viewModelTypeName = viewTypeName.Replace("View", "ViewModel");
            var viewModelType = Type.GetType(viewModelTypeName);
            var viewModel = Activator.CreateInstance(viewModelType);
            ((FrameworkElement)d).DataContext = viewModel;
        }
    }
}

Using this pattern makes the views and viewmodels sort themselves out, which is great, but I don't have any reference to the view from the viewmodel, so now I want to be able to click a button in a UserControl and close the Window containing it.

I use RelayCommand and Binding to execute the command.

Is there a better way to close the current window than to use var window = Application.Current.Windows[0]; to get a reference to the currently open window, and then close it?

Does this answer your question? [Close Window from ViewModel](https://stackoverflow.com/questions/16172462/close-window-from-viewmodel) — Pavel Anikhouski, Nov 30 '19 at 16:41
@PavelAnikhouski, sorry, it doesn't. I'll edit my question to explain why. An oversight on my part, really. — mathgenius, Nov 30 '19 at 16:46
To not break the MVVM, what about invoking an event from the viewmodel to which the ``Window`` would subscribe? — Corentin Pane, Nov 30 '19 at 20:29
@CorentinPane, but how do I get a reference to the UserControlViewModel in order to subscribe to the event? — mathgenius, Dec 01 '19 at 00:15
@CorentinPane, I am using a ViewModelLocator and the ViewModel is the one that is tied to the UserControl View, not the Window. — mathgenius, Dec 01 '19 at 11:43

WPF - Close window from UserControl ViewModel when using ViewModelLocator pattern

0 Answers0