Strange behaviour of .NET binary serialization on Dictionary

Question

I encountered a, at least to my expectations, strange behavior in the binary serialization of .NET.

All items of a Dictionary that are loaded are added

Answer 1

Interesting... for info, I tried it with the attribute-based approach (below), and it behaves the same... very curious! I can't explain it - I'm just replying to confirm reproduced, and to mention the [OnDeserialized] behaviour:

[OnDeserialized] // note still not added yet...
private void OnDeserialized(StreamingContext context) {...}

Edit - found "connect" issue here. Try adding to your callback:

Dictionary.OnDeserialization(this);

Answer 2

I can reproduce the problem. Had a look around Google and found this: http://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=94265 although I'm not sure it's the exact same problem, it seems pretty similar.

EDIT:

I think that adding this code may have fixed the problem?

    public void OnDeserialization(object sender)
    {
            this.Dictionary.OnDeserialization(sender);
    }

No time to exhaustively test, and I want to beat Marc to the answer ;-)

Answer 3

Yes, you've discovered an annoying quirk in Dictionary<TKey, TValue> deserialization. You can get around it by manually calling the dictionary's OnDeserialization() method:

public void OnDeserialization(object sender)
{
    Dictionary.OnDeserialization(this);
    TestsLengthsOfDataStructures(this);
}

Incidentally, you can also use the [OnDeserialized] attribute rather than IDeserializationCallback:

[OnDeserialized]
public void OnDeserialization(StreamingContext context)
{
    Dictionary.OnDeserialization(this);
    TestsLengthsOfDataStructures(this);
}