Caliburn Micro publish / subscribe

Question

I'm working through the following tutorial http://www.mindscapehq.com/blog/index.php/2012/2/1/caliburn-micro-part-4-the-event-aggregator/ and I'm currently stuck at the publish / subscribe part.

I have everything set up, so that it should actually publish the events but the subscribing viewmodel doesn't get the message.

I've done the following:

Publishing ViewModel:

[Export(typeof(ColorViewModel))]
public class ColorViewModel : PropertyChangedBase
{
    private readonly IEventAggregator events;

    [ImportingConstructor]
    public ColorViewModel(IEventAggregator events)
    {
        this.events = events;
    }

    public void Red()
    {
        this.events.PublishOnUIThread(new ColorEvent(new SolidColorBrush(Colors.Red)));
    }

    public void Green()
    {
        this.events.PublishOnUIThread(new ColorEvent(new SolidColorBrush(Colors.Green)));
    }

    public void Blue()
    {
        this.events.PublishOnUIThread(new ColorEvent(new SolidColorBrush(Colors.Blue)));
    }
}

Subscribing ViewModel:

[Export(typeof(AppViewModel))]
public class AppViewModel : PropertyChangedBase, IAppViewModel, IHandle<ColorEvent>
{
    private IEventAggregator events;

    [ImportingConstructor]
    public AppViewModel(ColorViewModel colorViewModel, IEventAggregator events)
    {
        this.ColorViewModel = colorViewModel;

        this.events = events;
        this.events.Subscribe(this);
    }

    public ColorViewModel ColorViewModel { get; private set; }

    private SolidColorBrush color;

    public SolidColorBrush Color
    {
        get
        {
            return this.color;
        }

        set
        {
            this.color = value;
            this.NotifyOfPropertyChange(() => this.Color);
        }
    }

    public void Handle(ColorEvent message)
    {
        this.Color = message.Color;
    }
}

There are 3 radio buttons on the ColorView which I can click and I do get into the Red(), Green(), Blue() methods so that the PublishOnUIThread is called. But I never reach the Handle(ColorEvent) method of the AppViewModel.

Am I missing something or why doesn't my handle method gets called after publishing the ColorEvents?

Thanks in advance

Answer 1

Where is the event aggregator coming from? Is it the same instance shared between AppViewModel and ColorViewModel?

Make sure the event aggregator is registered as a singleton in the dependency injector.