diff --git a/Toolkit.Foundation/IValueInvoker.cs b/Toolkit.Foundation/IValueInvoker.cs
new file mode 100644
index 0000000..6bac696
--- /dev/null
+++ b/Toolkit.Foundation/IValueInvoker.cs
@@ -0,0 +1,6 @@
+namespace Toolkit.Foundation;
+
+public interface IValueInvoker<TValue>
+{
+    public void Invoke(TValue args);
+}
diff --git a/Toolkit.Foundation/ObservableViewModel.cs b/Toolkit.Foundation/ObservableViewModel.cs
index 47a45b0..7bd5543 100644
--- a/Toolkit.Foundation/ObservableViewModel.cs
+++ b/Toolkit.Foundation/ObservableViewModel.cs
@@ -83,6 +83,21 @@ public partial class ObservableViewModel<TValue>(IServiceProvider provider,
     IDisposer disposer) : ObservableViewModel(provider, factory, mediator, publisher, subscriber, disposer)
     where TValue : notnull
 {
+    [ObservableProperty]
+    private TValue? value;
+}
+
+public partial class ObservableViewModel<TKey, TValue>(IServiceProvider provider,
+    IServiceFactory factory,
+    IMediator mediator,
+    IPublisher publisher,
+    ISubscriber subscriber,
+    IDisposer disposer) : ObservableViewModel(provider, factory, mediator, publisher, subscriber, disposer)
+    where TValue : notnull
+{
+    [ObservableProperty]
+    private TKey? key;
+
     [ObservableProperty]
     private TValue? value;
 }
\ No newline at end of file