Null reference exception during Base64 deserialization (C #)

Question

I use the following methods to serialize and deserialize .NET objects:

public static string SerializeToBase64(object data) { var stream = new MemoryStream(); var formatter = new BinaryFormatter(); formatter.Serialize(stream, data); stream.Position = 0; return Convert.ToBase64String(stream.ToArray()); } public static object DeserializeFromBase64(string data) { var stream = new MemoryStream(Convert.FromBase64String(data)); stream.Position = 0; var formatter = new BinaryFormatter(); return formatter.Deserialize(stream); } 

These methods seem to work just fine when dealing with simple classes marked with the [Serializable] attribute.

But I need to use this code to serialize entity classes (also made as Serializable) created by the ORM framework, with each entity class coming from a base class for which I don't have source code.

When working with instances of an entity class, it completes serialization with no exceptions, but deserialization always throws a reference zero of exception when excecuting formatter.Deserialize ().

I am not very familiar with the serialization process, but I assume that this problem should be caused by something abnormal in the state of the target. Is there a standard set of criteria that an object must meet before serialization?

Any other debugging suggestions would be appreciated.

Thanks Tim

UPDATE:

After further experimentation, I think I discovered the cause of the problem. The target has events that are handled by another class that is not marked as serializable, as described in this post .

Interestingly, serialaztion works correctly, even with attached event handlers - this is deserialization that fails.

But I tested by temporarily removing event handlers, and serialization and deserialization work correctly, so I assume this is a problem. However, since I do not have access to the code in which the events are declared, I cannot immediately see how to implement the solution described above. Perhaps I need to modify the serialization process to remove and then restore event handlers.

Answer 1

What is the ORM structure? Please note that types with ORM code are usually especially unpleasant when used with BinaryFormatter , because they are not always "POCO": they often have fields that are related to ORM, therefore, to create their own problems. In short, I am not very surprised that in this case it does not work.

You might want to use something like DataContractSerializer , XmlSerializer , protobuf-net, or perhaps NetDataContractSerializer - they all do the same job, but since they work with public properties (not fields), they tend to be more efficient - and many of them have built-in support for these approaches for use as DTOs.

Answer 2

Can I use Reflector to build an ORM base class? There may be some kind of custom deserialization code that ISerializable exception (i.e., that implements the ISerializable interface). If you find that this is the case and what it does, you can set sufficient state in the instance of the subclass to prevent this from happening. On the other hand, if he has a mistake, then you are a little out of luck.