Please suggest me the ( Interaction model of view model) MVVM design in the simple scenario discussed in the subject/

Answer 1

Rather than give you a specific design, I'm going to suggest a different way of looking at the problem.

Make your xaml. Now, if it could have the data organized in any way exposing any set of methods it wanted, what would that look like? Don't even think about the real structure of the entities when imagining this. More inheritance? Less? Up to you - whatever would be best for your View.

Okay, whatever you just described is your ViewModel. Write the public API for that. Then, hook it up to the actual underlying entities.

Answer 2

Is your main problem in how to create the correct View for the selected Order type? ie How does the drop down or the ListView trigger the correct Order view to be displayed.

If that's what you're getting at then you're going to want something like: When the user clicks on the list of Orders (for example) you'll need to change the some underlying ObservableCollection and send out some kind of notification or force it to do something on some kind of Workspace object. Probably the best way to understand that is to look at the MvvmDemoApp by Josh Smith as well as his article if you haven't already read it. From there zero in on the way he implements the WorkspaceViewModel as I think that might be the approach, or something like that, you are after for your Order view user controls. (if I've understood you correctly).