WebApi 2，OWIN和AutoFac-更改HttpContextBase依赖项

Question

Recently I decided that I would like to integrate test my WebApi 2 application. I decided to convert my application to OWIN compliant. I have included all the NuGet packages and hooked it up with AutoFac middleware and so on.

However when I try to test the application with HttpClient in in Main method of sample program, I get an error:

{
  "Message":"An error has occurred.",
  "ExceptionMessage":"An error occurred when trying to create a controller of type 'DinnerListController'. Make sure that the controller has a parameterless public constructor.",
  "ExceptionType":"System.InvalidOperationException",
  "StackTrace":"   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)\r\n   at System.Web.Http.Controllers.HttpControllerDescriptor.CreateController(HttpRequestMessage request)\r\n   at System.Web.Http.Dispatcher.HttpControllerDispatcher.<SendAsync>d__1.MoveNext()",
  "InnerException":{
    "Message":"An error has occurred.",
    "ExceptionMessage":"An exception was thrown while executing a resolve operation. See the InnerException for details. ---> Value cannot be null.\r\nParameter name: httpContext (See inner exception for details.)",
    "ExceptionType":"Autofac.Core.DependencyResolutionException",
    "StackTrace":"   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Lifetime.LifetimeScope.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.ResolutionExtensions.TryResolveService(IComponentContext context, Service service, IEnumerable`1 parameters, Object& instance)\r\n   at Autofac.ResolutionExtensions.ResolveOptionalService(IComponentContext context, Service service, IEnumerable`1 parameters)\r\n   at Autofac.Integration.WebApi.AutofacWebApiDependencyScope.GetService(Type serviceType)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.GetInstanceOrActivator(HttpRequestMessage request, Type controllerType, Func`1& activator)\r\n   at System.Web.Http.Dispatcher.DefaultHttpControllerActivator.Create(HttpRequestMessage request, HttpControllerDescriptor controllerDescriptor, Type controllerType)",
    "InnerException":{
      "Message":"An error has occurred.",
      "ExceptionMessage":"Value cannot be null.\r\nParameter name: httpContext",
      "ExceptionType":"System.ArgumentNullException",
      "StackTrace":"   at System.Web.HttpContextWrapper..ctor(HttpContext httpContext)\r\n   at Autofac.Integration.Mvc.AutofacWebTypesModule.<Load>b__0(IComponentContext c)\r\n   at Autofac.RegistrationExtensions.<>c__DisplayClass10`1.<Register>b__f(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Builder.RegistrationBuilder.<>c__DisplayClass1`1.<ForDelegate>b__0(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n   at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Activators.Reflection.AutowiringParameter.<>c__DisplayClass2.<CanSupplyValue>b__0()\r\n   at Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate()\r\n   at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n   at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Activators.Reflection.AutowiringParameter.<>c__DisplayClass2.<CanSupplyValue>b__0()\r\n   at Autofac.Core.Activators.Reflection.ConstructorParameterBinding.Instantiate()\r\n   at Autofac.Core.Activators.Reflection.ReflectionActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.<Execute>b__0()\r\n   at Autofac.Core.Lifetime.LifetimeScope.GetOrCreateAndShare(Guid id, Func`1 creator)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.ResolveComponent(IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Registration.ExternalRegistrySource.<>c__DisplayClass8.<RegistrationsFor>b__3(IComponentContext c, IEnumerable`1 p)\r\n   at Autofac.Core.Activators.Delegate.DelegateActivator.ActivateInstance(IComponentContext context, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Activate(IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.InstanceLookup.Execute()\r\n   at Autofac.Core.Resolving.ResolveOperation.GetOrCreateInstance(ISharingLifetimeScope currentOperationScope, IComponentRegistration registration, IEnumerable`1 parameters)\r\n   at Autofac.Core.Resolving.ResolveOperation.Execute(IComponentRegistration registration, IEnumerable`1 parameters)"
    }
  }
}

I isolated the cause: it's my service which has dependency on HttpContextBase for storing and extracting something from cookies:

public CookieUserService(HttpContextBase httpContext)

and AutoFac can't initialize this class. When I tried another implementation, without HttpContextBase , dependency it works.

So the question is: is there a way to get access to cookies while using OWIN, so I could refactor the service and get rid of HttContextBase (and Web.dll ) dependecies?

Answer 1

While switching to OWIN, all dependencies on System.Web and so on become invalid, as they are coupling tight the application with IIS hosting environment. Therefore AutoFac is not able to inject HttpContextBase as dependency to my service, because it can't instan.

In order to overcome the problem, instead of using System.Web dependencies like HttpContextBase , service should depend on OWIN specific interfaces, which provide abstraction between application and hosting environment.

In my specific case, I changed the service to depend on IOwinContext, like so:

public OwinCookieUserService(IOwinContext owinContext)
{
    if (owinContext == null) throw new ArgumentNullException(nameof(owinContext));  
    _owinContext = owinContext;
}

After adding two additional NuGet packages:

1. Autofac.Owin
2. Autofac.WebApi2.Owin

I was able to glue together AutoFac and OWIN in my Startup class:

public class Startup
{
   public void Configuration(IAppBuilder appBuilder)
   {
       var httpConfiguration = new HttpConfiguration();
       ...
       AutoFacConfig.ConfigureAutoFac(httpConfiguration);
       appBuilder.UseAutofacMiddleware(AutoFacConfig.Container);
       appBuilder.UseAutofacWebApi(httpConfiguration);
       appBuilder.UseWebApi(httpConfiguration);
   }
}

In my AutoFac mappings, I have the following routine that where I define my service dependency:

....
    builder.RegisterType<OwinCookieUserService>().AsImplementedInterfaces().InstancePerLifetimeScope();
....

That is basically it! I didn't have to specifically setup mappings for OWIN interfaces and classes, it just works. I hope that will help some of you folks in the future.