public void GetNavigationGroupItems(string navGroup, out string error)
        {
            error = "";
            NavigationItemsList.Clear();

            try
            {
                foreach (NavigationItems item in _context.usp_ST_Metrics_GetNavigationGroupItems(navGroup))
                {
                    _navigationItem = new NavigationItemDataModel
                    {
                        NavigationItem = item.NavigationItem
                    };
                    NavigationItemsList.Add(_navigationItem);
                }
            }
            catch (Exception ex)
            {
                string msg = string.Format("Failed to return menu items for group {0}.  Error: ", navGroup);
                error = (ex.InnerException == null)
                    ? msg + ex.Message
                    : msg + ex.InnerException.Message;
            }
        }