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REST with polymorphic DataContracts - Deserialization Fails

It drove me crazy all the time since I hadn't made any changes, but I swear it worked the way I thought yesterday.

I have a WCF 4 REST service defined with the following contract:

[ServiceContract]
public interface IPhoneFeaturesManagementHost
{
    [OperationContract]
    [WebInvoke(Method = "POST", UriTemplate = "/accounts/{accountNumber}/phoneNumbers/{phoneNumber}/features/{featureType}", RequestFormat = WebMessageFormat.Xml, ResponseFormat = WebMessageFormat.Xml, BodyStyle = WebMessageBodyStyle.Bare)]
    void UpdateFeatureStatus(string accountNumber, string phoneNumber, string featureType, FeatureUpdateRequest updateRequest);
}

I also have the following types defined:

[DataContract]
[KnownType(typeof(One900FeatureUpdateRequest))]
public abstract class FeatureUpdateRequest
{
    [DataMember]
    public FeatureStatus Status { get; set; }

    [DataMember]
    public DateTime EffectiveDate { get; set; }

    public string AccountNumber { get; set; }
    public string PhoneNumber { get; set; }
    public string UserId { get; set; }
    public DateTime Timestamp { get; set; }

    public override string ToString()
    {
        return String.Format("Status: {0}, Effective Date: {1}", Status, EffectiveDate);
    }
}

[DataContract]
public class One900FeatureUpdateRequest : FeatureUpdateRequest
{
    [DataMember]
    public bool PerformSwitchUpdate { get; set; }
}

Yesterday, I swear I was able to submit the POST data of this form:

<One900FeatureUpdateRequest>
  <EffectiveDate>1999-05-31T11:20:00</EffectiveDate>
  <Status>Enabled</Status>
  <PerformSwitchUpdate>true</PerformSwitchUpdate>
</One900FeatureUpdateRequest>

Today, this same batch of XML is causing HTTP 400 errors with the following message:

Unable to deserialize XML body with root name 'One900FeatureUpdateRequest' and root namespace '' (for operation 'UpdateFeatureStatus' and contract ('IPhoneFeaturesManagementHost',  'http://tempuri.org/')) using DataContractSerializer. Ensure that the type corresponding to the XML is added to the known types collection of the service.

The only XML that seems to work today is below, and I really don't like the need to add the namespace plus attribute to describe the subtype of my child DataContract.

<FeatureUpdateRequest i:type="One900FeatureUpdateRequest" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/Project.Services.Host">
  <EffectiveDate>1999-05-31T11:20:00</EffectiveDate>
  <Status>Enabled</Status>
  <PerformSwitchUpdate>true</PerformSwitchUpdate>
</FeatureUpdateRequest>

Does anyone have any ideas as to what I might have affected, or what I might need to change in order to revert to the previous simple XML format for deserialization?

. !

+5
1

DataContractSerializer, XmlSerializer, XML-. , .

+1

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