Bson serialization allow objects to implement ISupportInitialize
and it will call appropriate methods. But I had not found any opposite method.
I think, it would be great to have some custom interface, e.g.:
interface IBsonSerializationHook
{
void BeforeSerialize();
void AfterDeserialize();
}
So it will be easy to do some work before serialization and after deserialization.
I have a use case for this:
There is a document per user {_id:123, ReadArticleIds:[1,2,3,4,5.... 10000]}
ReadArticleIds may contain thousands of Ids. If i just save/load it, it takes forever (more then a second for one record) to load.
But, I know, that I need ReadArticleIds only in memory, I will not be doing any queries against it. So I serialize it with BinaryFormatter and save it in BsonBinaryData. Now it will load/save 100 times faster at least. Even with overhead of binaryformatter.

I tried to implement IBsonSerializable and inside do my stuff and just call BsonSerializer.Seriaze(). But that obviuously caused stack overflow

Also, I just don't like doing such hacky customization. Code would be much easier to understand with appropriate interface/method names.