BsonKnownTypes Attribute Support

[Turnerj]

While MongoFramework handles polymorphism when dealing with a derived type, there isn't functionality to support something like the MongoDB C# Driver's BsonKnownTypes attribute.

You can still use the native one but it doesn't apply any additional mapping through MongoFramework's entity mapper.

It might be useful to just leverage that exact attribute and make a custom mapping processor use it to apply entity mapping that is native to MongoFramework.

It would be ideal to just make this apply at runtime and for some things it is possible. It is possible to apply runtime mapping for any writes (as the entity type is available) however runtime mapping for reads is both complex and would impact performance.

Assuming one could inject code into the serialization process for the C# driver, it would be taking the string type discriminator in the DB and finding the right type in the right assembly to convert to. This is possible with reflection but is a pretty average solution.

[Turnerj]

With Runtime Type Detection, you no longer need to specify known types at compile time. It is opt-in and requires the RuntimeTypeDiscovery attribute on the desired class.

This solves part of the problem in that during deserialization that types are then mapped through the entity mapper. It doesn't however map them during serialization which is another important step.

Plus if you didn't want to use RuntimeTypeDiscovery, it would still be a good idea to look for the BsonKnownTypes attribute and grab the types from there.