How to Configure AutoMapper Once Per AppDomain

Question

My current project with assemblies for the domain model, MVC web application, and unit tests. How can I set up the AutoMapper configuration so that all assemblies reference

Answer 1

I have been moving my AutoMapper CreateMap calls into classes that live beside my view models. They implement an IAutomapperRegistrar interface. I use reflection to find the IAutoMapperRegistrar implementations, create an instance and add the registrations.

Here is the interface:

public interface IAutoMapperRegistrar
{
    void RegisterMaps();
}

Here is an implementation of the interface:

public class EventLogRowMaps : IAutoMapperRegistrar
{
    public void RegisterMaps()
    {
        Mapper.CreateMap()
            .ConstructUsing(he => new EventLogRow(he.Id))
            .ForMember(m => m.EventName, o => o.MapFrom(e => e.Description))
            .ForMember(m => m.UserName, o => o.MapFrom(e => e.ExecutedBy.Username))
            .ForMember(m => m.DateExecuted, o => o.MapFrom(e => string.Format("{0}", e.DateExecuted.ToShortDateString())));
    }
}

Here is the code that performs the registrations in my Application_Start:

foreach (Type foundType in Assembly.GetAssembly(typeof(ISaveableModel)).GetTypes())
{
    if(foundType.GetInterfaces().Any(i => i == typeof(IAutoMapperRegistrar)))
    {
        var constructor = foundType.GetConstructor(Type.EmptyTypes);
        if (constructor == null) throw new ArgumentException("We assume all IAutoMapperRegistrar classes have empty constructors.");
        ((IAutoMapperRegistrar)constructor.Invoke(null)).RegisterMaps();
    }
}

I figure it's appropriate and at least a bit logical; they are a lot easier to follow that way. Before I had hundreds of registrations in one huge bootstrap method and that was starting to become a pain in the ass.

Thoughts?