OnActionExecuting.cs

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
  // Retrieve the information what we need to log
  string routeInfo = GetRouteData(filterContext.RouteData);
  string user = filterContext.HttpContext.User.Identity.Name;

  Debug.WriteLine(String.Format("ActionExecuting - {0} ActionType: {1}; User:{2}"
     , routeInfo, ActionType, user), "Audit Log");

  base.OnActionExecuting(filterContext);
}