Binding the Loaded event?

Question

I am trying to display a login window once my MainWindow loads while sticking to the MVVM pattern. So I am trying to Bind my main windows Loaded event to an event in my view

Answer 1

Use Attached Behavior. That is allowed in MVVM ....

(code below may / may not compile just like that)

XAML ...

Code Behind...

  class MainWindowViewModel : ViewModelBase
  {
      private ICommand _showLogInWindowCommand;

      public ICommand ShowLogInWindowCommand
      {
         get
         {
              if (_showLogInWindowCommand == null)
              {
                  _showLogInWindowCommand = new DelegateCommand(OnLoaded)
              }
              return _showLogInWindowCommand;
         }
      }

      private void OnLoaded()
      {
          //// Put all your code here....
      }
  } 

And the attached behavior...

  public static class MyAttachedBehaviors
  {
      public static DependencyProperty LoadedCommandProperty
        = DependencyProperty.RegisterAttached(
             "LoadedCommand",
             typeof(ICommand),
             typeof(MyAttachedBehaviors),
             new PropertyMetadata(null, OnLoadedCommandChanged));

      private static void OnLoadedCommandChanged
           (DependencyObject depObj, DependencyPropertyChangedEventArgs e)
      {
          var frameworkElement = depObj as FrameworkElement;
          if (frameworkElement != null && e.NewValue is ICommand)
          {
               frameworkElement.Loaded 
                 += (o, args) =>
                    {
                        (e.NewValue as ICommand).Execute(null);
                    };
          }
      }

      public static ICommand GetLoadedCommand(DependencyObject depObj)
      {
         return (ICommand)depObj.GetValue(LoadedCommandProperty);
      }

      public static void SetLoadedCommand(
          DependencyObject depObj,
          ICommand  value)
      {
         depObj.SetValue(LoadedCommandProperty, value);
      }
  }

DelegateCommand source code can be found on the internet... Its the most suited ICommand API available for MVVM.

edit:19.07.2016 two minor syntax errors fixed