Question

I can easily understand how to use custom events in pure C# code, but how can I do pass in custom event arguments on asp:button click?

I’ve tried all sorts of things (defining new event args, new delegates, etc etc) but I have had no luck.

Is there a tutorial of how to do this with the standard asp controls?

Answer 1

As long as your EventArgs inherit from System.EventArgs you will be able to pass them. Then, once inside your event handler, you can cast the event to the proper subtype.

Here is an example:

using System;  class Program {     static event EventHandler Foo;      static void Main()     {         // Here is cast the EventArgs to FooEventArgs         Foo += (o,e) => Console.WriteLine(((FooEventArgs)e).Number);          // Notice that I am passing a 'FooEventArgs' instance         // even though the delegate signature for 'EventHandler'         // specifies 'EventArgs'.  Polymorphism in action. :)         Foo(null, new FooEventArgs { Number = 1 });     } }  class FooEventArgs : EventArgs {     public int Number { get; set; } } 

I know that you are working with existing control delegates so unfortunately this kind of casting is neccessary. Keep in mind though that there is a EventHandler<T> where T : EventArgs delegate in .NET 2.0 and greater that will allow you to do what I have done above without casting.