DataContract and inheritance?

Question

How to use DataContract with inheritance? Will code below work?

[DataContract]
public class ConsoleData
{
    [DataMember]
    public String Description { ge         


        

Answer 1

You'll need to use the KnownType attribute if you are using the XmlSerializerFormat for your ServiceContract:

[DataContract]
public class ConsoleData
{
    [DataMember]
    public String Description { get; set; }
}

[DataContract, KnownType(typeof(ConsoleData))]
public class SomeData : ConsoleData
{
    [DataMember]
    public int Volume { get; set; }
}

Answer 2

Yes, that would work.

The DataContractAttribute has Inherited set to false, so it is necessary to apply the attribute to both the child class and the parent class (as you have done in the question).

---

You would need to use the KnownType attribute if you want to use your data contracts with polymorphism.

For example

 [ServiceContract]
 interface MyWcfContract
 {
       [OperationContract]
       HandleData(ConsoleData contractData);
 }

If you invoked the method like so:

 SomeData someData = new SomeData { Description = "Test", Volume = 30 };
 // The method is expecting a ConsoleData instance, 
 // I'm passing a SomeData instance instead
 myWcfProxy.HandleData(someData);

Then the deserializer on the service end will not know that it's an instance of SomeData, just an instance of ConsoleData which it was expecting. The way to fix this is to register the SomeData class as a known type of the ConsoleData.

[DataContract]
[KnownType(typeof(SomeData))]
public class ConsoleData
{
    [DataMember]
    public String Description { get; set; }

}

[DataContract]
public class SomeData : ConsoleData
{

    [DataMember]
    public int Volume { get; set; }
    ......