Does the OnActionExecuted method of an attribute always execute?

Question

I've searched high and low and I can't seem to find a straight answer.

If I have a custom attribute/filter, will the OnActionExecuted method always be called? Even if there is an exception thrown?

Answer 1

At least with MVC 5, @tvanfosson's answer is no longer correct. This may apply to earlier versions as well.

OnActionExecuted is always called and has access to the thrown exception via filterContext.Exception.

Test case with exception in an action:

public class HomeController
    : Controller
{
    public ActionResult Index()
    {
        throw new Exception("Index");
    }
}

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new Foo());
        filters.Add(new Bar());
    }
}

public class Foo
    : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Debug.WriteLine($"{nameof(Foo)}.{nameof(OnActionExecuting)}");
        base.OnActionExecuting(filterContext);
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        Debug.WriteLine($"{nameof(Foo)}.{nameof(OnActionExecuted)}");
        Debug.WriteLine($"Has exception: {filterContext.Exception != null}");
        base.OnActionExecuted(filterContext);
    }
}

public class Bar
    : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Debug.WriteLine($"{nameof(Bar)}.{nameof(OnActionExecuting)}");
        base.OnActionExecuting(filterContext);
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        Debug.WriteLine($"{nameof(Bar)}.{nameof(OnActionExecuted)}");
        Debug.WriteLine($"Has exception: {filterContext.Exception != null}");
        base.OnActionExecuted(filterContext);
    }
}

Output:

Bar.OnActionExecuting
Foo.OnActionExecuting
Exception thrown: 'System.Exception' in WebApplication1.dll
Foo.OnActionExecuted
Has exception: True
Bar.OnActionExecuted
Has exception: True

Test case with exception in a filter

public class HomeController
    : Controller
{
    public ActionResult Index()
    {
        return new HttpStatusCodeResult(200);
    }
}

public class FilterConfig
{
    public static void RegisterGlobalFilters(GlobalFilterCollection filters)
    {
        filters.Add(new Foo());
        filters.Add(new Bar());
    }
}

public class Foo
    : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Debug.WriteLine($"{nameof(Foo)}.{nameof(OnActionExecuting)}");
        base.OnActionExecuting(filterContext);
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        Debug.WriteLine($"{nameof(Foo)}.{nameof(OnActionExecuted)}");
        Debug.WriteLine($"Has exception: {filterContext.Exception != null}");
        throw new Exception("Foo");
        base.OnActionExecuted(filterContext);
    }
}

public class Bar
    : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        Debug.WriteLine($"{nameof(Bar)}.{nameof(OnActionExecuting)}");
        base.OnActionExecuting(filterContext);
    }

    public override void OnActionExecuted(ActionExecutedContext filterContext)
    {
        Debug.WriteLine($"{nameof(Bar)}.{nameof(OnActionExecuted)}");
        Debug.WriteLine($"Has exception: {filterContext.Exception != null}");
        base.OnActionExecuted(filterContext);
    }
}

Output:

Bar.OnActionExecuting
Foo.OnActionExecuting
Foo.OnActionExecuted
Has exception: False
Exception thrown: 'System.Exception' in WebApplication1.dll
Bar.OnActionExecuted
Has exception: True