About wcf rest return list - wcf

Question

Server side interface:
[OperationContract]
[WebGet(UriTemplate = "GetCardInfoByCardNumber/?cardNumber={cardNumber}&SerialNumber={SerialNumber}&token={token}", ResponseFormat = WebMessageFormat.Json)]
IList<Cards> GetCardInfoByCardNumber(string cardNumber, string SerialNumber, string token);
Server side implementation:
public IList<Cards> GetCardInfoByCardNumber(string cardNumber, string SerialNumber, string token)
{
if (BaseClass.HasPermission(token))
return cm.GetCardInfoByCardNumber(cardNumber, SerialNumber);
else
return null;
}
Client side:
class Program
{
static void Main(string[] args)
{
TestResWCF();
Console.ReadLine();
}
static List<Cards> TestResWCF()
{
List<Cards> a = null;
string ServiceUri = "http://192.168.15.18:8089/GetCardInfoByCardNumber/?cardNumber=HH-120109-017&SerialNumber=&token=123456";
WebClient proxy = new WebClient();
proxy.Encoding = Encoding.UTF8;
proxy.DownloadStringCompleted += new DownloadStringCompletedEventHandler
(
(s, e) =>
{
Stream stream = new MemoryStream(Encoding.Unicode.GetBytes(e.Result));
DataContractJsonSerializer obj = new DataContractJsonSerializer(typeof(List<Cards>));
a = obj.ReadObject(stream) as List<Cards>;
}
);
proxy.DownloadStringAsync(new Uri(ServiceUri));
return a;
}
List<Cards> a return empty string always! How to return data? Thank you very much!
Do you have any example? sorry for my bad english

Answer 1

Can you share the code for the "Cards" and "Card" classes?
I'm very sure that most likely, it is not decorated with [DataContract] and [DataMember] properly. You may have decorated the type with [DataContract], but forgotten to annotate the members you want with [DataMember]. Or alternatively, you may not have decorated them at all, and something else is happening behind the scenes. In 99% of the scenarios, misdecoration or improper decoration or mis-initialization of the serializer is the reason this error occurs.
If you did decorate it properly, there may be some other problems. It's hard to tell with 100% certainty from just the detail you've provided, so I'd enable tracing to generate tracing logs (that you can then view/share with SvcTraceViewer) and turn on debug exceptions (by turning on the includeExceptionDetailInFaults setting).