Question

I have WCF service that return Json.

Data contract defined below

  [DataContract]
    public class OptionData
    {
        [DataMember]
        public string Book { get; set; }
        [DataMember]
        public string Id { get; set; }
        [DataMember]
        public string DealId { get; set; }
        [DataMember]
        public string DeliveryDate { get; set; }
        [DataMember]
        public string ExpiryDate { get; set; }
   }

And Operation Contract defined as follows

[Description("Returns List of Options by user id")]
        [WebGet(UriTemplate = "{sessionId}/Application/{applicationId}?start={start}&limit={limit}&page={page}", ResponseFormat = WebMessageFormat.Json)]
        public List<OptionData> GetAllTask(string sessionId, string applicationId)

I need to add dynamically new DataMember field to the OptionData class .

What is the best practice to do it ?

Answer 1

If you know you want JSON, you could always control the serialization yourself (see this post) – just return a string of JSON using an existing library.

Another option is to just us IsRequired = false if you know all the possible field names.

The final alternative is to use the same pattern WCF uses for Forward-Compatible Contracts – just attach all unknown properties to single collection object (ExtensionData). ExtensionData is just a dictionary of key/value pairs according to this post. Unfortunately – ExtensionData is not writable directly. This would be my approach to simulate what IExtensibleDataObject is doing…

[DataContract]
public class OptionData 
{
    [DataMember]
    public string Book { get; set; }
    [DataMember]
    public string Id { get; set; }
    [DataMember]
    public string DealId { get; set; }
    [DataMember]
    public string DeliveryDate { get; set; }
    [DataMember]
    public string ExpiryDate { get; set; }
    [DataMember]
    public Dictionary<string, string> Metadata { get; set;}
}