MVC - filterContext.ExceptionHandled

Question

Does the filterContext.ExceptionHandled property ever get set to true by MVC or is it only set to true by user code? If so where does this happen?

Answer 1

filterContext.ExceptionHandled get set to true when an exception is thrown by an action method. By default HandleErrorAttribute has been added in FilterConfig class which is registered in Application_Start(). When an exception occurs, the OnException method is called in HandleErrorAttribute class.

In OnException method, before removing the current HTTP response body by using Response.Clear(), the ExceptionHandled property will set to true.

Below is the default OnException method:

public virtual void OnException(ExceptionContext filterContext)
{
    if (filterContext == null)
    {
        throw new ArgumentNullException("filterContext");
    }
    if (filterContext.IsChildAction)
    {
        return;
    }
    if (filterContext.ExceptionHandled || !filterContext.HttpContext.IsCustomErrorEnabled)
    {
        return;
    }
    Exception exception = filterContext.Exception;
    if (new HttpException(null, exception).GetHttpCode() != 500)
    {
        return;
    }
    if (!ExceptionType.IsInstanceOfType(exception))
    {
        return;
    }
    string controllerName = (string)filterContext.RouteData.Values["controller"];
    string actionName = (string)filterContext.RouteData.Values["action"];
    HandleErrorInfo model = new HandleErrorInfo(filterContext.Exception, controllerName, actionName);

    filterContext.Result = new ViewResult
    {
        ViewName = View,
        MasterName = Master,
        ViewData = new ViewDataDictionary<HandleErrorInfo>(model),
        TempData = filterContext.Controller.TempData
    };
    filterContext.ExceptionHandled = true;
    filterContext.HttpContext.Response.Clear();
    filterContext.HttpContext.Response.StatusCode = 500;
    filterContext.HttpContext.Response.TrySkipIisCustomErrors = true;
}