Jonathan Birkholz

ISubscribe

I believe Jimmy Bogard has a similar technique (IHandler) with ASP .Net MVC but I thought I would still share the convention I’ve been using to wire up subscriptions to the Prism Event Aggregator.

Whenever an object is built with StructureMap, it goes through all the TypeInterceptors. I have a SubscriptionTypeInterceptor:

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public class SubscriptionInterceptor : TypeInterceptor

{

    public object Process(object target, IContext context)

    {

        var eventAggregator = context.GetInstance<IEventAggregator>();



        // Get interface ISubscribe<E>

        var interfaces = target.GetType().GetInterfaces().Where(i => i.Name.Contains("ISubscribe"));



        foreach (var type in interfaces)

        {

            // typeof(E)

            var eventType = type.GetGenericArguments()[0];



            var setupMethod = GetType().GetMethod("Setup");

            setupMethod.MakeGenericMethod(eventType).Invoke(this, new[] { target, eventAggregator });

        }



        return target;

    }



    public bool MatchesType(Type type)

    {

        return type.ImplementsInterfaceTemplate(typeof(ISubscribe<>));

    }



    public void Setup<T>(ISubscribe<T> subscriber, IEventAggregator eventAggregator)

    {

        eventAggregator

            .GetEvent<CompositePresentationEvent<T>>()

            .Subscribe(subscriber.Subscribe);

    }

}

So it finds all the ISubscribe interfaces the target implements and then subscribes the target to the event T in the event aggregator.

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public interface ISubscribe<E>

{

    void Subscribe(E e);

}

A simple example of usage:

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public class SecurityController : IController,

                                  ISubscribe<RequestUserLoginEvent>

{

    public void Subscribe(RequestUserLoginEvent e)

    {

        Publish.Event().ShowModal<IRequestUserLoginViewModel>();

    }

}