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I'm conducting a test using JOlivers CommonDomain and EventStore with NServiceBus. I need to raise an event in my Aggregate like this:

RaiseEvent(bus.CreateInstance<IPhoneNumberChanged>(m => { m.Number = number; }));

And then later i have this handler:

private void Apply(IPhoneNumberChanged phoneNumberChangedEvent)
{
    this.Number = phoneNumberChangedEvent.Number;
}

Unfortunately this doesn't work. I get an exception: "CommonDomain.Core.HandlerForDomainEventNotFoundException: Aggregate of type 'Phone' raised an event of type 'IPhoneNumberChanged' but not handler could be found to handle the message.".

The problem here is the object created from "bus.CreateInstance" since it works with pure concrete classes. But I need my events as interfaces. Can this be solved?

EDIT: Just a note - I don't have to use "bus.CreateInstance" to create the object, it's just the easiest (only) way I currently have to raise the 'IPhoneNumberChanged'. Any other way would also be great - just as long as I have an interface as argument in the handler.

Ruben Bartelink
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Werner
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1 Answers1

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In your constructor for your Phone aggregate, simply add the following:

this.Register<IPhoneNumberChanged>(this.Apply);

That will take care of the exception. The default internal routing mechanism inside of the CommonDomain is a registration-based router than understands how to get an event to the appropriate Handle method--all without using reflection. Another router has been written and is already part of the CommonDomain project which uses reflection and is more convention based.

One quick thought regarding your event name. Rather than saying that the phone number changed, you may want the event to indicate why the phone number changed. From a domain perspective, the why of something is always more interesting and important that the what. The fact that a phone number changed usually isn't interesting. The fact that it changed because the person moved or cancelled their account or whatever--that's interesting and very likely important as well.

Jonathan Oliver
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  • Hi Jonathan, unfortunately it doesn't work. I have debugged it and while the name is the same (IPhoneNumberChanged) the Type isn't. The type constructed from Bus.CreateInstance is "MyDomain.__Impl.IPhoneNumberChanged" and the type registered is "MyDomain.IPhoneNumberChanged". And since the "MyDomain__Impl.IPhoneNumberChanged" is created at runtime only I can't register it in CommonDomain. Any advices? – Werner Sep 05 '11 at 07:16
  • I guess a "this.Register(Type, action)" is basically what I'm looking for? Or are there another solution? – Werner Sep 05 '11 at 07:22
  • On second thoughts, forget my last comment. Such registration would have to be done each time an event object is created. – Werner Sep 05 '11 at 07:45