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I have data stored in an instance of a class which has been serialized with the .net BinaryFormatter. I now want to rename one of the fields in the class, but still be able to deserialize the old data.
One option is to implement ISerializable and deserialize all the the fields of the class manually. But this seems like a lot of work, especially if my class has lots of fields and I've only renamed a single field.
Is there a better way?
Craig suggests keeping a copy of the old class for deserialization, and copying values to the new class. I've seen this suggested elsewhere too - what advantage does this have over implementing ISerializable? As far as I can see, copying the class leaves me with 2 almost identical copies of the class plus I still have to copy all the values from the old class to the new class - which seems the same amount of work as implementing ISerializable with an almost duplicate class thrown into mix.
Two answers have mentioned Binders. I've successfully used a SerializationBinder to deserialize a class Bar which was Serialized as class Foo, but that's because the name of the class changed. Does SerializationBinder also help when you've renamed a field - say when int m_Left has been renamed to int m_Right?
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Serialization is the process of converting an object into a stream of bytes to store the object or transmit it to memory, a database, or a file. Its main purpose is to save the state of an object in order to be able to recreate it when needed. The reverse process is called deserialization.
Serialization or marshaling is the process of converting object state into a format that can be transmitted or stored. The serialization changes the object state into series of bits. The object state could be reconstructed later in the opposite process, called deserialization or unmarshalling .
To serialize an object means to convert its state to a byte stream so way that the byte stream can be reverted back into a copy of the object. A Java object is serializable if its class or any of its superclasses implements either the java.
Yes, this is the problem with field-based serializers. You can use either a custom Binder, or a "serialization surrogate" to avoid implementing ISerializable, but that is only a case-by-case fix.
I've discussed this topic (in the context of obfuscators, and auto-props) here. My advice is: don't use BinaryFormatter for persistance of data between versions... for that, look at contract-based serializers:
XmlSerializerDataContractSerializerNone of this helps you today, but it might help you design around it in the future.
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