I'm trying to write a F# driver implementation that wraps what the C# driver does. Right now the main thing that I'm getting stuck on is deserializing immutable record types. If I have this F# record:

type Person =

{ Id : BsonObjectId Name : string }

it compiles to [roughly] this C# code

public class Person
{
private readonly BsonObjectId id;
private readonly string name;

public Person(BsonObjectId id, string name)

{ this.id = id; this.name = name; }

public BsonObjectId Id { get

{ return id; }

}
public string Name { get

{ return name; }

}
}

I can configure the BsonClassMapSerializer to serialize objects just fine, however when I try deserializing it skips all the properties of the record because they don't have setter methods.

A big part of the problem is that BsonClassMapSerializer does 90% of what I need, but it's an internal class. Even if it were public, it's too much of a behemoth to be able to customize via subclassing. A better solution might be to add configuration to class maps. Perhaps an interface such as:

interface IMemberAccumulator

{ object Initialize(Type nominalType); void AccumulateMember(object state, Type nominalType, MemberInfo memberInfo, object value); object GetFinalValue(object state, Type nominalType); }

and a `BsonClassMap.SetMemberAccumulator(IMemberAccumulator)` would probably get me what I need. I'm sure this sort of thing might even be useful for other languages, including C#.

https://github.com/tkellogg/MongoDB.FSharp