Setting up Autofac

 Autofac is very nice DI container, but documentation on their site is lacking on specifics.
 This is how I set up Autofac in global.asax.cs:


  protected void Application_Start()
   {
     RegisterAutofac();

     AreaRegistration.RegisterAllAreas();
     GlobalConfiguration.Configure(WebApiConfig.Register);
     FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
     RouteConfig.RegisterRoutes(RouteTable.Routes);
     BundleConfig.RegisterBundles(BundleTable.Bundles);
      
  }


and then do registration of all the things you want injected:

private void RegisterAutofac()
 {
   var builder = new ContainerBuilder();
   var config = GlobalConfiguration.Configuration;
   // all controllers are going to be built by autofac
   builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
   // concrete implementation first, interface second
   builder.RegisterType<ItemRepository>().As<IItemRepository>();

   //
   var container = builder.Build();
   config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
}