Monday, May 7, 2012

Adding AutoRegistration to the Microsoft Unity container

The default way to use an IoC container is to register all objects and their dependencies yourself. So somewhere in your code you have a long list of registrations like:
var container=new UnityContainer();
container.Register<ITypeA,TypeA>();
container.Register<ITypeB,TypeB>();
container.Register<ITypeC,TypeC>();
container.Register<ITypeD,TypeD>();
container.Register<ITypeE,TypeE>();
container.Register<ITypeF,TypeF>();
...


Most IoC containers allow you to simplify this registration process by using ‘AutoRegistrations’. Based on some rules or conventions, your assemblies are scanned for types and if these types match those rules, there are registered in the IoC container automatically.
The Microsoft Unity container does not include autoregistration out-of-the-box. However you can use  the Unity Auto Registration addon by Artem Govorov.


“Unity Auto Registration extends Unity IoC container and provides fluent syntax to configure rules for automatic type registration. Using few code lines you can scan specified assemblies and register all types that satisfy your rules. Rules for determining whether to include/exclude type/assembly are predicates (Predicate<T>) so you can use lambda syntax to specify them or direct method name. There are a few methods in If helper class (like Implements, DecoratedWith) to cover some common scenarios of type registering.”


A sample of the fluent interface:


var container = new UnityContainer();

            container
                .ConfigureAutoRegistration()
                .LoadAssemblyFrom("MyApp.dll")
                .ExcludeSystemAssemblies()
                .ExcludeAssemblies(a => a.GetName().FullName.Contains("Test"))
                .Include(If.Implements<ILogger>, Then.Register().UsingPerCallMode())
                .Include(If.ImplementsITypeName, Then.Register().WithTypeName())
                .Include(If.Implements<ICustomerRepository>, Then.Register().WithName("Sample"))
                .Include(If.Implements<IOrderRepository>,
                         Then.Register().AsSingleInterfaceOfType().UsingPerCallMode())
                .Include(If.DecoratedWith<LoggerAttribute>,
                         Then.Register()
                                .As<IDisposable>()
                                .WithTypeName()
                                .UsingLifetime<MyLifetimeManager>())
                .Exclude(t => t.Name.Contains("Trace"))
                .ApplyAutoRegistration();

1 comment:

Anonymous said...

Any chance of an example project ?