DataContractSerializer cannot deserialize after namespace changed

Question

I have 50 classes marked with DataContractAttribute.

These classes form a huge hierarchical tree, which is serialized/deserialized using the DataContractSerializer to xml.

All of them specify a custom datacontract namespace [DataContract(Namespace="http://example.com")], except for 3 classes, which I've missed.

// Old class definitions 
[DataContract(IsReference=true)]  // <-- forgot ns
public class Type1{}
[DataContract(IsReference=true)] // <-- forgot ns
public class Type2{}
[DataContract(IsReference=true)] // <-- forgot ns
public class Type3{}
[DataContract(IsReference=true, Namespace="http://example.com")] // <-- 47 more like this
public class Type4{} 

I want these 3 classes to use the same datacontract namespace as the other 47 classes.

After the change, all my previously-saved xmls fails to load.

// Changed to:
[DataContract(IsReference=true, Namespace="http://example.com")] // <-- changed ns
public class Type1{} 
[DataContract(IsReference=true, Namespace="http://example.com")] // <-- changed ns
public class Type2{} 
[DataContract(IsReference=true, Namespace="http://example.com")] // <-- changed ns
public class Type3{} 
[DataContract(IsReference=true, Namespace="http://example.com")]
public class Type4{}

I tried this method:

DataContractSerializer - change namespace and deserialize file bound to old namespace

But got a SerializationException saying Deserialized object with reference id 'i5' not found in stream.

How can I deserialize xmls saved before and after the namespace change?

Answer 1

I would personally change the data contract and then create a script that parses the previously saved xmls to add the namespace info. Quick and simple.

Something like loading xmls as string and then calling:

xmlstr=xmlstr.Replace("<Type1>", "<Type1 xmlns:Namespace=\"http://example.com\">");

Or maybe create two classes (one with the old namespace and one with the new) create a mapping method so that you can deserialize the old xmls based on the old namespace and serialize them after mapping with the new namespace.