Publishing collection of INotifications

[jblackburn21]

In v2.1 I was able to loop through a collection of INotifications and publish the events since it used var notificationType = notification.GetType(); to determine the exact notification type of the handlers to execute. In v3, it uses var notificationType = typeof(TNotification);, which causes it to look for handlers that implement IAsyncNotificationHandler. Can this be changed back to the original behavior?

[jbogard]

Not sure what the problem is, do you have a snippet that shows the bad behavior? I want to write a test for this and I'm not sure what I'm aiming for.

[jblackburn21]

Here is a variation of the unit test. I collect a list of events and then publish them at the end of my process, so the list could contain different types.

[Fact]
        public async Task Should_resolve_handler_for_list_of_generic_notifications()
        {
            var builder = new StringBuilder();
            var writer = new StringWriter(builder);

            var container = new Container(cfg =>
            {
                cfg.Scan(scanner =>
                {
                    scanner.AssemblyContainingType(typeof(AsyncPublishTests));
                    scanner.IncludeNamespaceContainingType<Ping>();
                    scanner.WithDefaultConventions();
                    scanner.AddAllTypesOf(typeof(IAsyncNotificationHandler<>));
                });
                cfg.For<TextWriter>().Use(writer);
                cfg.For<IMediator>().Use<Mediator>();
                cfg.For<SingleInstanceFactory>().Use<SingleInstanceFactory>(ctx => t => ctx.GetInstance(t));
                cfg.For<MultiInstanceFactory>().Use<MultiInstanceFactory>(ctx => t => ctx.GetAllInstances(t));
            });

            var mediator = container.GetInstance<IMediator>();

            var pings = new List<INotification>()
            {
                new Ping {Message = "Ping"}
            };

            foreach (var ping in pings)
            {
                await mediator.Publish(ping);
            }

            var result = builder.ToString().Split(new[] { Environment.NewLine }, StringSplitOptions.None);
            result.ShouldContain("Ping Pong");
        }

[jbogard]

Ah, makes sense.

[jblackburn21]

I was able to get it to work by adding the handler wrappers back in. Let me know what you think. It is currently missing the wrapper cache, but I can get those added in as well.

https://github.com/jbogard/MediatR/compare/master...jblackburn21:feature/NotificationHandlerWrapper?expand=1

Also, thanks for fixing my other issue. I was able to verify it after I got this working.

[remcoros]

I am running into this as well when dynamically publishing notifications.

I added a failing test here: remcoros@244659d

Note that it publishes using the notification base type like this:

INotification ping = new Ping()
mediatr.Publish(ping);

As @jblackburn21 said, this is because typeof(TNotification) is used instead of notification.GetType() as the notification type.