Bus failing to publish interface-defined event when messageConstructor not defined

[thirkcircus]

When publishing using interface-defined events and when the messageConstructor not defined, an exception is thrown and the event is not published.

I came across an error situation which should have been a lot quicker to identify the root cause.

Using NServiceBus.Core 4.3.0 and NServiceBus.RabbitMQ 3.2.1
I have an event ITestEvent with one property. I'm also using Unobtrusive mode (have been for ages, this isn't a new message type).
If my commandhandler executes the following code it all works as expected:

public override void Handle(TestCommand command)
{
    LogTo.Info("Processing a {0} command...", command.GetType().Name);
    Bus.Publish<ITestEvent>(e => e.TestId = Guid.NewGuid());
}

but if my commandhandler executes the following code (forgetting to specify the messageConstructor for the event):

public override void Handle(TestCommand command)
{
    LogTo.Info("Processing a {0} command...", command.GetType().Name);
    Bus.Publish<ITestEvent>();  // oops, forgot to set the event properties
}

then I get the following error log:

NServiceBus.Unicast.Transport.TransportReceiver - "Failed to process message" with exception 
System.Exception: Could not find Metadata for 'System.Object'.
Please ensure the following:
1. 'System.Object' is included in initial scanning see File Scanning: http://particular.net/articles/the-nservicebus-host
2. 'System.Object' implements either 'IMessage', 'IEvent' or 'ICommand' or alternatively, if you don't want to implement an interface, you can use 'Unobtrusive Mode' see: http://particular.net/articles/unobtrusive-mode-messages
   at NServiceBus.Unicast.Messages.MessageMetadataRegistry.GetMessageDefinition(Type messageType) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\Messages\MessageMetadataRegistry.cs:line 18
   at NServiceBus.Unicast.Messages.LogicalMessageFactory.<CreateMultiple>b__0(Object m) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\Messages\LogicalMessageFactory.cs:line 53
   at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at NServiceBus.Unicast.Messages.LogicalMessageFactory.CreateMultiple(IEnumerable`1 messages) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\Messages\LogicalMessageFactory.cs:line 48
   at NServiceBus.Unicast.UnicastBus.Publish[T](T[] messages) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\UnicastBus.cs:line 305
   at NServiceBus.Unicast.UnicastBus.Publish[T](T message) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\UnicastBus.cs:line 276
   at NServiceBus.Unicast.UnicastBus.Publish[T](T[] messages) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\UnicastBus.cs:line 295
   at NServiceBus.Unicast.UnicastBus.Publish[T]() in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\UnicastBus.cs:line 284
   at Xero.PostOffice.Test5.TestCommandHandler.Handle(TestCommand command) in c:\Dev\temp\Xero.PostOffice.Test5\Xero.PostOffice.Test5\TestCommandHandler.cs:line 19
   at lambda_method(Closure , Object , Object )
   at NServiceBus.Unicast.HandlerInvocationCache.Invoke(Object handler, Object message, Dictionary`2 dictionary) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\HandlerInvocationCache.cs:line 61
   at NServiceBus.Unicast.HandlerInvocationCache.InvokeHandle(Object handler, Object message) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\HandlerInvocationCache.cs:line 22
   at NServiceBus.Unicast.Behaviors.LoadHandlersBehavior.<Invoke>b__1(Object handlerInstance, Object message) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\Unicast\Behaviors\LoadHandlersBehavior.cs:line 38
    SNIP
   at NServiceBus.UnitOfWork.UnitOfWorkBehavior.Invoke(ReceivePhysicalMessageContext context, Action next) in y:\BuildAgent\work\31f8c64a6e8a2d7c\src\NServiceBus.Core\UnitOfWork\UnitOfWorkBehavior.cs:line 20

So two questions:

1. My ITestEvent should only ever be published when all its properties have been specified - is there a way to enforce this?
2. Regardless, the error message isn't at all helpful - the error isn't a bad inheritance chain or unobtrusive msg settings, it's that I forgot to set the event properties. The error message is misleading.

[andreasohlund]

I'd say this is a bug since when you don't pass an action we should just create a new ITestEvent.. But that for some reason gets treated as a Object

[thirkcircus]

ok, ta.

when trying to repro, I have:
IEvent (my own marker interface, not the NSB one)
ITestEvent : IEvent
Unobtrusive convention:
config.DefiningCommandsAs(t => typeof(ICommand).IsImplementedBy(t))
.DefiningEventsAs(t => typeof(IEvent).IsImplementedBy(t))
.DefiningMessagesAs(t => typeof(ICommand).IsImplementedBy(t) || typeof(IEvent).IsAssignableFrom(t));

also, what about question 1 - is it possible to enforce all properties are set for a given event before publishing it?
cheers

[andreasohlund]

also, what about question 1 - is it possible to enforce all properties are
set for a given event before publishing it?

I'd say no, that is in my opinion not something that NSB should get
involved in. Wouldn't this be catched in unit/integration/acceptance tests?

On Tue, Dec 17, 2013 at 4:09 AM, Justin Thirkell
notifications@github.comwrote:

ok, ta.

when trying to repro, I have:
IEvent (my own marker interface, not the NSB one)
ITestEvent : IEvent
Unobtrusive convention:
config.DefiningCommandsAs(t => typeof(ICommand).IsImplementedBy(t))
.DefiningEventsAs(t => typeof(IEvent).IsImplementedBy(t))
.DefiningMessagesAs(t => typeof(ICommand).IsImplementedBy(t) ||
typeof(IEvent).IsAssignableFrom(t));

also, what about question 1 - is it possible to enforce all properties are
set for a given event before publishing it?
cheers

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