DataContract and Serializable in WCF Service
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I try to write a demo with WCF (REST) Service, and I use LinqToSQL as my db operator.
When I try to pub [DataContract] or [Serializable] on top of my domain object, it cannot be serialized to JSON. I only can get a pair of '{}' in my browser. After removing [DataContract] or [Serializable] attribute, it become normal again.

    [DataContract]
    public partial class MyDoc{ } // a Linq To SQL domain class

get method:

        [WebGet(UriTemplate = "GetMyDoc/{docID}",ResponseFormat=WebMessageFormat.Json)]       
        [ServiceKnownType(typeof(MyDoc))]
        public WcfRESTfulTest.Db.MyDoc GetMyDoc(string docID)
        {
            WcfRESTfulTest.Db.DbDataContext db = new DbDataContext();
            var query = db.MyDocs.Where(d => d.DocID.Equals(Int32.Parse(docID)));
            return query.FirstOrDefault();
        }
