Filters of GlobalFilterCollection run before Filters of ControllerInstanceFilterProvider

Question

I came across a weird behavior but I am not sure if I am on the right track here.

I have a controller which overrides OnException method of the Controller base class.

public class ControllerFiltersController : Controller {

    public ActionResult Index() {

        throw new NotImplementedException();
    }

    protected override void OnException(ExceptionContext filterContext) {

        Trace.TraceInformation(
            "ControllerFiltersController Exception: " + DateTime.Now.ToString("hh:mm:ss.fff")
        );
    }
}

I also have an custom ExceptionFilter as follows:

public class HandleErrorCustom : IExceptionFilter {

    public void OnException(ExceptionContext filterContext) {

        Trace.TraceInformation(
            "HandleErrorCustom Exception Message: " + DateTime.Now.ToString("hh:mm:ss.fff")
        );
    }
}

Then, I registered it as a global filter:

public static void RegisterGlobalFilters(GlobalFilterCollection filters) {

    filters.Add(new HandleErrorCustom());
}

What I expected is here for the controller instance filter to run before global filter since the order of filters which are provided by ControllerInstanceFilterProvider is Int32.MinValue and the scope of them is FilterScope.First.

As also explained here: ASP.NET MVC 3 Service Location, Part 4: Filters

But the result is different:

iisexpress.exe Information: 0 : HandleErrorCustom Exception Message: 06:56:49.972

iisexpress.exe Information: 0 : ControllerFiltersController Exception: 06:56:49.974

This is an ASP.NET MVC 4 application and I am not aware of any changes which effects the filter ordering behavior of ASP.NET MVC 3. What am I missing here?

Answer 1

This is expected behavior.

Filter ordering depends on the direction the information is flowing. If the information is flowing into the action, then the order is as you expect it; if the information is flowing back out of the action, then the order is reversed.

For example, assume you have three filters in this order: F1, F2, F3. Assume that these are action filters (meaning, they're listening to ActionExecuting and ActionExecuted). The order the system will run them is as follows:

F1.ActionExecuting()
F2.ActionExecuting()
F3.ActionExecuting()
Action()
F3.ActionExecuted()
F2.ActionExecuted()
F1.ActionExecuted()

Error handlers are, by definition, filters that run on the return-side of actions, so their order is reversed.