Prism Event Aggregation - subscriber not triggered

Question

I'm working on implementing an event aggregation with Prism. I have a few modules, and I want each of them to subscribe to events that tells them when they are requested. I started out doing an all plain example with both subscribed and publisher in the shell. No problems there. Now; when I move the subscribers out to my modules they don't get triggered. What's even more odd is that it actually has worked a few times - all of which I've been pending in a breakpoint. So it seems to me to be some race condition, but I don't understand why.

Assumption made: I don't need to set up the IEventAggregator anywhere - e.g. registering in the IoC container? This is built into Prism such that I only have one instance of the event aggregator, right?

So, the question is basically how/where/when I should set up my subscribers. Is there a specific order on stuff etc? In my simplified example I have one module MyModule. The Bootstrapper will add MyModule to the catalog - making it initialized:

catalog.AddModule(typeof(MyModule));

MyModule will store the aggregator and use this for subscribing to the MyModuleRequestedEvent. It also uses a menu registry to register in the application menu. The idea is that eventually clicking in the menu should trigger the event - notifying MyModule that it has been requested. Then I want it to be MyModule's responsibility to figure out what to do further.

public MyModule(IEventAggregator aggregator, IApplicationMenuRegistry menu)
{
    _applicationMenu = menu;
    _aggregator = aggregator;
}

public void Initialize()
{
    var evnt = _aggregator.GetEvent();
    evnt.Subscribe(MyModuleRequested);
    _applicationMenu.RegisterMenuItem("MyModule", evnt);
}

public void MyModuleRequested(bool b)
{
    MessageBox.Show("MyModule requested");
}

Now, I have a button in my shell which will publish this event. The shell gets the same (?) event aggregator when resolved.

public Shell(IEventAggregator aggregator)
{
    InitializeComponent();
    var evnt = aggregator.GetEvent();
    EventTriggerButton.Click += (s, e) => evnt.Publish(true);
}

Notes:

Have verified that the event is published. Adding a subscriber in the shell too will make this subscriber receive the event.
Again; the subscriber in MyModule isn't triggered. However, it has - strangely - been on a few occasions.
I don't use the input to the event. It seemed like you needed to have some input-type, so I just went with a dummy bool. Can I get rid of this..?

Prism Event Aggregation - subscriber not triggered

2 Answers