/// <summary>
        /// 根据角色ID获取角色信息
        /// </summary>
        /// <param name="id"></param>
        /// <returns></returns>
        public Roles GetRoleByID(string id)
        {
            if (id == null)
            {
                id = string.Empty;
            }

            var data = from r in RoleList.AsNoTracking()
                       where r.RoleID == id
                       select r;

            if (data.Count() > 0)
            {
                return(data.First());
            }
            else
            {
                return(null);
            }
        }