WPF

DialogResultEx dlgResult = new DialogResultEx();
dlgResult.DialogResult = dialog.DialogResult;
dlgResult.DialogData = viewModel.WhateverData;    //Modify as needed

public abstract class _DialogBaseViewModel
{
    public virtual object DialogData { get { return null; } }
}

public class InputDialogViewModel : _DialogBaseViewModel
{
    private string _textData = string.Empty;

    public override object DialogData
    {
        get
        {
            return _textData;
        }
    }
}

public static class DialogService
{
    private static Dictionary<Type, Type> registry = new Dictionary<Type, Type>();

    public static void RegisterDialog(Type dialogType, Type viewModelType)
    {
        if (!dialogType.IsSubclassOf(typeof(Window)))
        {
            throw new ArgumentException("The dialogType must be a subclass of type Window.");
        }

        bool exists = registry.Where(x => x.Key == dialogType).Any();

        if (!exists)
        {
            registry.Add(dialogType, viewModelType);
        }
    }

    public static bool? ShowDialog<TViewModelType>(TViewModelType viewModel) where TViewModelType : _DialogBaseViewModel
    {
        Type dialogType = registry.Where(x => x.Value == viewModel.GetType()).Select(x => x.Key).FirstOrDefault();
        var dialog = (Window)Activator.CreateInstance(dialogType);

        dialog.DataContext = viewModel;
        dialog.ShowDialog();

        return dialog.DialogResult.Value;
    }
}

public static class DialogManager
{
    static DialogManager()
    {
        // Register all dialogs here
        DialogService.RegisterDialog(typeof(SQLConnectionView), typeof(SQLConnectionViewModel));
    }

    public static string OpenSQLConnectionDialog()
    {
        string result = string.Empty;

        SQLConnectionViewModel vm = new SQLConnectionViewModel();

        bool? dialogResult = DialogService.ShowDialog(vm);

        if (dialogResult.Value)
        {
            result = vm.ConnectionString;
        }

        return result;
    }
}

var connString = DialogManager.OpenSQLConnectionDialog();

public static DialogResultEx ShowDialog<TViewModelType>(TViewModelType viewModel) where TViewModelType : _DialogBaseViewModel
{
    Type dialogType = registry.Where(x => x.Value == viewModel.GetType()).Select(x => x.Key).FirstOrDefault();

    if (dialogType == null)
    {
        throw new ArgumentException(string.Format("There is no registered dialog corresponding to a view model of type {0}.", viewModel));
    }

    var dialog = (Window)Activator.CreateInstance(dialogType);

    dialog.DataContext = viewModel;
    dialog.ShowDialog();

    DialogResultEx dlgResult = new DialogResultEx();
    dlgResult.DialogResult = dialog.DialogResult;
    dlgResult.DialogData = viewModel.DialogData;

    return dlgResult;
}




public static DialogResultEx ShowDialog<TViewModelType, TOwnerType>(TViewModelType viewModel, Type ownerType) where TViewModelType : _DialogBaseViewModel
{
    Type dialogType = registry.Where(x => x.Value == viewModel.GetType()).Select(x => x.Key).FirstOrDefault();

    if (dialogType == null)
    {
        throw new ArgumentException(string.Format("There is no registered dialog corresponding to a view model of type {0}.", viewModel));
    }



    var dialog = (Window)Activator.CreateInstance(dialogType);

    dialog.DataContext = viewModel;

    if (ownerType != null)
    {
        Window ownerWindow = FindWindow(ownerType);
        dialog.Owner = ownerWindow;
    }

    dialog.ShowDialog();

    DialogResultEx dlgResult = new DialogResultEx();
    dlgResult.DialogResult = dialog.DialogResult;
    dlgResult.DialogData = viewModel.DialogData;

    return dlgResult;
}

DialogResultEx dialogResult1 = DialogService.ShowDialog<SQLConnectionViewModel>(new SQLConnectionViewModel());

DialogResultEx dialogResult2 = DialogService.ShowDialog<SQLConnectionViewModel, MainWindowView>(new SQLConnectionViewModel(), typeof(MainWindowView));

public static DialogResultEx ShowDialog<TViewModelType>(TViewModelType viewModel, Type ownerType) where TViewModelType : _DialogBaseViewModel
        {
            Type dialogType = registry.Where(x => x.Value == viewModel.GetType()).Select(x => x.Key).FirstOrDefault();
 
            if (dialogType == null)
            {
                throw new ArgumentException(string.Format("There is no registered dialog corresponding to a view model of type {0}.", viewModel));
            }
 

 
            var dialog = (Window)Activator.CreateInstance(dialogType);
 
            dialog.DataContext = viewModel;
 
            if (ownerType != null)
            {
                Window ownerWindow = FindWindow(ownerType);
                dialog.Owner = ownerWindow;
            }
            
            dialog.ShowDialog();
 
            DialogResultEx dlgResult = new DialogResultEx();
            dlgResult.DialogResult = dialog.DialogResult;
            dlgResult.DialogData = viewModel.DialogData;
 
            return dlgResult;
        }

public static DialogResultEx ShowDialog<TViewModelType>(TViewModelType viewModel) where TViewModelType : _DialogBaseViewModel
        {
            return ShowDialog<TViewModelType>(viewModel, null);
        }

Kevin Marois wrote:

I was thinking of writing an article