CODEWITHSUNDEEP
c#xnasystem.reflectionmethodinfo
ThomasSquall
ThomasSquall

Reputation: 717

MethodInfo.Invoke TargetException

I've an Issue with System.Reflection, when I call MethodInfo.Invoke method it gaves me the TargetException exception that says: Object does not match with target, Here the code:

object[] parms = new object[] { path };

Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();
Type gameType = null;

foreach (Assembly asm in assemblies)
{
    string asmName = asm.GetName().Name;

    if (asmName == "Tester")
    {
        gameType = asm.GetType("Tester.Main");
        break;
    }
}

var game = Convert.ChangeType(GameInstance, gameType);
Type delegateType = game.GetType().GetEvent("gameVideoLoader").EventHandlerType;

MethodInfo method = delegateType.GetMethod("Invoke");
method.Invoke(game,  parms); // Here the exception

Any Idea? PS: game object is correctly assigned so it's not null

Upvotes: 0

Views: 1186

Answers (2)

Eli Arbel
Eli Arbel

Reputation: 22739

What Jon said.

Also, if you're trying to do some hacking (and not production-level code), here's some practical advice: take a look at the source code (or use a disassembler such as Reflector or dotPeek) and see how the event is invoked.

  • If there's a method that invokes it, use Reflection to call that method

  • Otherwise, if the event is using a compiler-generated field, use Type.GetField to retrieve the field (it would have the same name as the event) and then call GetValue to get the actual delegate

    • If the delegate type is public, cast the value and invoke

      ((MyDelegate)fieldValue)(arg1, arg2...)

    • Otherwise, cast to Delegate and use the dynamic invoke method

      ((Delegate)fieldValue).DynamicInvoke(new object[] { arg1, arg2 })

Upvotes: 2

Jon Skeet
Jon Skeet

Reputation: 1500375

You're trying to call the delegate's Invoke method, but on a Tester.Main instance. That's just wrong - because the Tester.Main instance isn't an instance of the appropriate delegate.

If you're trying to actually raise the gameVideoLoader event, then that's a different matter... and something that you shouldn't be doing anyway. The purpose of events is to allow clients to subscribe and unsubscribe handlers - the object itself should be responsible for raising the event. You may be able to find an underlying field which is used to implement the event, get the value of that field and invoke the delegate - but I'd strongly advise against it. You're basically going against the design of events at this point.

Upvotes: 1

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