Register on specific changed property in MVVM Light on WP7

I've created a view with a listbox on it which shows a collection of Cars on it. If a user clicks on a specific car, 开发者_StackOverflow中文版he needs to be sent to a different view with some detailed information on it. The binding properties are normal MVVM Light properties (with RaisePropertyChanged and all). Some code snippets:

<ListBox ItemsSource="{Binding Cars}" SelectedItem="{Binding SelectedCar, Mode=TwoWay}">

While developing this application I've discovered I can register for property changed events using the Messenger object of MVVM Light, like so:

Messenger.Default.Register<PropertyChangedMessage<Car>>(this, (action) =>
{
    Deployment.Current.Dispatcher.BeginInvoke(() =>
    {
        DoViewDetail();
    });
});

But if I'm correct, this will register for every changed Car in the whole application. It's probably possible to do something with the RaisePropertyChanged or Register so you can target a specific property, but I can't find seem to find it.

Anyone here got a clue or heads up? In short: I want to register on a specific property, not a specific object in my MVVM Light application.

---

I think one alternative is to create a custom "message" to use only in connection with the desired functionality. For example declare a CarSelectedMessage and then instead of using the default broadcasting of PropertyChangedMessage<Car>, create and send the custom message from the view model:

public Car SelectedCar { 
    get { return _selectedCar; }
    set { 
        _selectedCar = value;
        RaisePropertyChanged("SelectedCar");

        var msg = new CarSelectedMessage(value);
        Messenger.Default.Send(msg);
    }
}

On navigation in general

For implementing navigation in the application, I followed this blog post to make it simple to issue navigation requests from view models. I think it had to be updated a little for the latest version of MVVM Light though, see my version below.

New NavigationRequest class to be used as the message:

public class NavigationRequest
{
    public NavigationRequest(Uri uri)
    {
        DestinationAddress = uri;
    }

    public Uri DestinationAddress
    {
        get;
        private set;
    }
}

Register for requests in the constructor of the application's main view:

Messenger.Default.Register<NavigationRequest>(this, 
    (request) => DispatcherHelper.CheckBeginInvokeOnUI(
         () => NavigationService.Navigate(request.DestinationAddress)));

Finally for calling navigation from a view model

var uri = new Uri("/MyPage.xaml", UriKind.Relative);
Messenger.Default.Send(new NavigationRequest(uri));

Hope this helps,