public string GetUserId(XDocument xml) { var logins = CustomSerializer.Deserializ <SysAdminUnit>(new MemoryStream(Encoding.UTF8.GetBytes(xml.ToString() ?? ""))); var respond = new SysAdminUnitResponed(); foreach (var login in logins.items) { respond.items.Add(new ItemRespond() { ErrorCode = 1, ErrorDescription = "error1", IsSuccess = true, UserOneCGuid = Guid.NewGuid() }); } var stream = CustomSerializer.Serializ(respond); var srteamReader = new StreamReader(stream); return(srteamReader.ReadToEnd()); }