OnActionExecuted.cs

public override void OnActionExecuted(ActionExecutedContext filterContext)
{
  // Retrieve the information what we need to log
  string routeInfo = GetRouteData(filterContext.RouteData);

  bool isActionSucceeded = filterContext.Exception == null;
  string user = filterContext.HttpContext.User.Identity.Name;

  Debug.WriteLine(String.Format("ActionExecuted - {0} ActionType: {1}; Executed successfully:{2}; User:{3}"
      , routeInfo, ActionType, isActionSucceeded, user), "Audit Log");

  base.OnActionExecuted(filterContext);
}