How to handle the back button on WP 8.1 using MVVM light?

[admin]

I'm searching for the appropiate way to handle the back button pressed event on Windows Phone 8.1 WinRT using the

NavigationService

available on MVVM light 5.

So far I think the best place to do it is inside the

ViewModelLocator

by registering the

GoBack

method of the

NavigationService

while creating it following the approach outlined in <a href="https://marcominerva.wordpress.com/2014/10/10/navigationservice-in-mvvm-light-v5/" rel="nofollow">NavigationService in MVVM Light V5</a>

This is an effective approach. However, I can't handle validation before navigating back so I was wondering if there is a more suitable way to handle this event.

public class ViewModelLocator
{
    public ViewModelLocator()
    {
        ServiceLocator.SetLocatorProvider(() => SimpleIoc.Default);
        // Register NavigationService
        SimpleIoc.Default.Register(CreateNavigationService);
        // Register ViewModels here
    }

    private INavigationService CreateNavigationService()
    {
        var navigationService = new NavigationService();
        // Register pages here
        navigationService.Configure("Details", typeof(DetailsPage));
        // Handle back button
        HardwareButtons.BackPressed += (sender, args) => {
            navigationService.GoBack();
            args.Handled = true;
        }; 
        return navigationService;
    }
}