Autofac InstancePerRequest returns new isntance - asp.net

Question

I have an ASP.NET Web API, .Net 4.6.1 project where I need to capture some info in the middleware and then retrieve it in a code that will be called from controller. In .Net core it is very easy with registering my custom context class as Scoped and resolving it in different stages of message processing. In .Net Framework, what looked similar to it was Autofac's InstancePerRequest so I tried but it does not work as I expected. Apparently every time I do BeginScope() it returns a new instance even if I am within same reuest? I am implementing the IAutofacContinuationActionFilter interface where I resolve my service, registered with InstancePerRequest, then later in controller I try to resolve it again and get new instance. What am I missing here?
Oh and in the controller below, both instances of IHomeService: injected via constructor and resolved manually are creating new instances.
UPDATE:
The code above is oversimplification of the real situation. The call where I need the information passed from filter is in a separate class and call happens through a series of autogenerated code. The constructor injection is not an option for me so I was hoping to have a solution similar to .Net Core DI.
my WebApiConfig:
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
// Web API configuration and services
var container = MyContainerBuilder.Build(config);
config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
// Web API routes
config.MapHttpAttributeRoutes();
config.Routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
}
}
my container builder class:
public class MyContainerBuilder
{
public static IContainer Build(HttpConfiguration config)
{
var builder = new ContainerBuilder();
builder.RegisterWebApiFilterProvider(config);
builder
.Register(c => new MyCustomFilter())
.AsWebApiActionFilterForAllControllers()
.InstancePerRequest();
// var assembly = typeof(IHomeService).Assembly;
// builder.RegisterAssemblyTypes(assembly).AsImplementedInterfaces().InstancePerRequest();
builder.RegisterApiControllers(Assembly.GetExecutingAssembly()).InstancePerRequest();
builder
.RegisterType<HomeService>()
.As<IHomeService>()
.InstancePerRequest();
return builder.Build();
}
}
filter:
public class MyCustomFilter : IAutofacContinuationActionFilter
{
public async Task<HttpResponseMessage> ExecuteActionFilterAsync(
HttpActionContext actionContext,
CancellationToken cancellationToken,
Func<Task<HttpResponseMessage>> next)
{
using (var scope = GlobalConfiguration.Configuration.DependencyResolver.BeginScope().GetRequestLifetimeScope())
{
var hs = scope.Resolve<IHomeService>();
++hs.Counter;
var hs1 = scope.Resolve<IHomeService>();
++hs1.Counter;
var r = next().Result;
return await Task.FromResult(r);
}
}
}
controller:
[Route("home")]
public class HomeController : ApiController
{
public IHomeService HomeService { get; set; }
public HomeController(IHomeService homeService)
{
HomeService = homeService;
}
[HttpGet]
[Route("")]
public string Index()
{
var dr = GlobalConfiguration.Configuration.DependencyResolver as AutofacWebApiDependencyResolver;
using (var scope = dr.GetRequestLifetimeScope())
// This does not work either, returns new instance:
// using (var scope = GlobalConfiguration.Configuration.DependencyResolver.BeginScope().GetRequestLifetimeScope())
{
var hs = scope.Resolve<IHomeService>();
++hs.Counter;
}
return "Home";
}
}
service class I try to resolve:
public interface IHomeService
{
int Counter { get; set; }
}
public class HomeService : IHomeService
{
public HomeService()
{
Console.WriteLine("Yet another instance of HomeService!!!");
}
public int Counter { get; set; }
}
Thanks in advance

Answer 1

You can't create your own request scope, you need to get it from the request message. In the filter, that's like:
var scope = actionContext.Request.GetDependencyScope();
An example filter showing this is in the Autofac docs
However, since you're using Autofac interfaces, they're injected by Autofac for each request - if your filter needs a per-request service, it's better to make it a constructor parameter on the filter. You only need to do service location if you're not using Autofac filter interfaces.
If you seriously need service location in the filter, you can still use the constructor to make things easier - add an ILifetimeScope parameter to the filter constructor and you'll get the request scope as a parameter.
For the controller, same thing: inject what you need in the constructor rather than using service location. If you need the request scope because you can't escape service location, either inject an ILifetimeScope into the controller constructor or get the request lifetime off the HttpRequestMessage.