GetEvent<>.Subscribe of event aggregator gives exception

Question

I am loading the dll's using reflection and I then try to execute a method in that dll. That method has this line that subscribes to an event. I get an exception at this line

This line is in a dll that I am invoking dynamically using reflection

evntAgg.GetEvent<ExceptionEvent>().Subscribe(Message);

and the exception is something like this:

The Target of the IDelegateReference should be of type System.Action`1[[CustomType, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]]. Parameter name: actionReference

this is the event handling method and is in the same dll that I am invoking dynamically

public void Message(ExceptionEvent exception)
{
//Do something
}

Any help would be appreciated?

I forgot to mention your username in the comment to my answer, so not sure if you got notified - just in case you weren't: Please read my answer again, the Message-method should has TEventArgs as parameter, not TEvent. — Spontifixus

Spontifixus Spontifixus · Accepted Answer · 2013-03-25T08:44:27

When using Prism's EventAggregator-class you will need to fulfill vertain requirements:

Define an event that derives from CompositePresentationEvent<TEventArgs>, where TEventArgs derives from System.EventArgs
Define a public method that handles your event, taking an instance of TEventArgs as parameter; for example:
```
public void HandleExceptionEvent(ExceptionEventArgs eventArgs)
{
}
```
The method needs to be public because otherwise the EventAggregator won't be able to invoke that method.
Subscribe to your event:
```
evntAgg.GetEvent<ExceptionEvent>.Subscribe(HandleExceptionEvent);
```
Given that you have implemented step 2 as described that should work without a problem.

GetEvent<>.Subscribe of event aggregator gives exception

1 Answers