Autofac, MVC (with ActionFilters), Web.Forms - dependency resolution conflict

asp.net-mvc, autofac, webforms

Solution

Actually there are two bugs? in Autofac which causing this behavior:

Bug #1: As side effect of the fix of Issue 351 the `AutofacDependencyResolver` needs to registered in the created Request bound `LifeTimeScope`s. The MVC intergration does this but the Winforms integration of course does not.

Bug? #2: Both the `RequestLifetimeScopeProvider` and the `ContainerProvider` stores the created `ILifetimeScope` with the same key `HttpContext.Current.Items`:

static ILifetimeScope LifetimeScope
{
    get { return (ILifetimeScope)HttpContext.Current.Items[typeof(ILifetimeScope)]; }
    set { HttpContext.Current.Items[typeof(ILifetimeScope)] = value; }
}

So there is a little bit race condition here because depending on which module gets executed first the WebForms or the MVC intergartion ILifetimeScope wins. So if the WebForms module wins the `AutofacDependencyResolver` won't be registered and you get the nice non descriptive exception.

Fix/workaround:

But there is an simple workaround: you just need to register the `AutofacDependencyResolver` in the `ContainerProvider` `requestLifetimeConfiguration` so no matter which one wins (WebForm vs. MVC) the `AutofacDependencyResolver` will be always registered:

var autofacDependencyResolver = new AutofacDependencyResolver(container);
DependencyResolver.SetResolver(autofacDependencyResolver);
_containerProvider = new ContainerProvider(container, requestContainerBuilder => 
     requestContainerBuilder.RegisterInstance(autofacDependencyResolver)
     .As<AutofacDependencyResolver>());

Problem

I've got a legacy Web.Forms app that been partially rewritten to MVC. MVC part uses autofac as a dependency injection container. MVC part have custom filter defined: ``` public class CustomActionFilter : ActionFilterAttribute { protected ILogger Logger { get; set; } public CustomActionFilter(ILogger logger) { Logger = logger; } public override void OnActionExecuting(ActionExecutingContext filterContext) { Logger.Log("OnActionExecuting"); } } ``` It works fine when Web.Forms integration is disabled in web.config. Hovewer, when I try to use Web.Forms autofac integration, I've got the NullReferenceException related to `AutofacFilterProvider` somewhere in autofac internals (stack trace). - Global.asax.cs: http://pastebin.com/437Tnp0t - web.config: http://pastebin.com/5pU6SH6c Note that `CustomActionFilter` is registered as global filter, thus it is registered with autofac: ``` public class FilterConfig { public static void RegisterGlobalFilters(GlobalFilterCollection filters) { filters.Add(new HandleErrorAttribute()); filters.Add(DependencyResolver.Current.GetService<CustomActionFilter>()); } } ``` I've tried: - using separate containers for MVC and Web.Forms - same result - Use property injection instead of constructor - same result - Explicitly trigger dependencies resolution on web.forms pages (like this) - worked So, the question is, are there any way to provide behind-the-scenes dependency resolution both to MVC and web.forms part. I'm new to autofac and somewhat new to dependency injection containers in general, so I might just miss something obvious. Update: error has nothing to do with custom filters. If I remove all references to custom filters the bug behavior still the same, even the stack trace.

Original source