title: prevent execution of default constructor in design time in ViewModel
body: <p>I put some data access logic in my default construct of ViewModel class.
  However, whenever try to open xaml designer window, visualstudio try to execute default constructor of ViewModel, then popup error window from this.</p>
  
  <p>How can I prevent execution of default constructor in ViewModel class.
  I know GetIsInDesignModel() method can do this in codebehind class, but it is impossible to use in ViewModel class because parameter of this method require DependencyObject type.</p>
  
  <p>any solution for this?</p>