Question

I have a UserControl UserControl1 and a button inside the UserControl1. And I have a UserControl1ViewModel that has an ICommand property for the button. Using this command I need to call a method outside(from other VMs or VM of the MainWindow) the VM. What is the best practice for this?

Answer 1

You might want to examine MVVM lite by Laurent Bugnion http://www.galasoft.ch/mvvm/getstarted/

This is a lightweight toolkit for helping enforce mvvm concepts. In it, every viewmodel is a static member in a ViewModelLocator class. So for instance, in your command you could do something like this.

ViewModelLocator.MainViewModel.MainContent = NewContent;

You can totally do this without mvvm lite, but using it really helps speed up the learning curve and enforce modularity.