MVVM Dialogs is a framework simplifying the concept of opening dialogs from a view model when using MVVM in WPF. It enables the developer to easily write unit tests for view models in the same manner unit tests are written for other classes.

The framework has built in support for opening the following dialogs:

• Modal window
• Non-modal window
• Message box
• Open file dialog
• Save file dialog
• Folder browser dialog

To open a modal window, decorate the view with the attached property DialogServiceViews.IsRegistered:

<UserControl
    x:Class="DemoApplication.Features.Dialog.Modal.Views.ModalDialogTabContent"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:md="https://github.com/fantasticfiasco/mvvm-dialogs"
    md:DialogServiceViews.IsRegistered="True">

  ...
  
</UserControl>

With the view registered the view model is now capable of opening a dialog using the interface IDialogService:

public class ModalDialogTabContentViewModel : INotifyPropertyChanged
{
    private readonly IDialogService dialogService;

    public ModalDialogTabContentViewModel(IDialogService dialogService)
    {
        this.dialogService = dialogService;
    }

    ...

    private void ShowDialog()
    {
        var dialogViewModel = new AddTextDialogViewModel();

        bool? success = dialogService.ShowDialog(this, dialogViewModel);
        if (success == true)
        {
            Texts.Add(dialogViewModel.Text);
        }
    }
}

If you want to include MVVM Dialogs in your project, you can install it directly from NuGet.

To install MVVM Dialogs, run the following command in the Package Manager Console:

PM> Install-Package MvvmDialogs