使用Caliburn.Micro的视图模型中的气泡事件

Question

I have a screen viewmodel with a search field and some results, composed of multiple, smaller viewmodels: a control for the search field, and a control instance for each result.

My "container" viewmodel (with the search and results) looks like this:

[Export(typeof(ShippingViewModel))]
public class ShippingViewModel : Screen, IHandle<SearchReferenceEvent>
{
    private readonly IEventAggregator events;

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

        this.Search = new QuickSearchViewModel(this.events);
    }

    public QuickSearchViewModel Search { get; set; }

    public void Handle(SearchReferenceEvent message)
    {
        System.Windows.MessageBox.Show(message.Reference);
    }
}

And the "quick search" (with the search fields) viewmodel:

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

    private string currentSearch;

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

    public string CurrentSearch // bound to the search field
    {
        get
        {
            return this.currentSearch;
        }

        set
        {
            this.currentSearch = value;
            this.NotifyOfPropertyChange(() => this.CurrentSearch);
        }
    }

    public void SearchReference(string reference) // bound to the search button
    {
        this.events.Publish(new SearchReferenceEvent(reference));
    }
}

The view is displayed as expected, and the search button triggers the SearchReference method.

But the event doesn't seem to be bubbled up to the ShippingViewModel , the Handle is never triggered.

Thanks!

Answer 1

Looks like you're never subscribing to the events in your ShippingViewModel . Try modifying your constructor like so:

[ImportingConstructor]
public ShippingViewModel(IEventAggregator events)
{
    this.events = events;
    this.events.Subscribe(this); // <= register to receive events

    this.Search = new QuickSearchViewModel(this.events);
}