DataMapper

I'm not sure if this is something you want to support, but I'm mentioning it because json encoding model/resource collections is important in my small corner of the world, and it should at least be noted in the documentation that Resource.all() returns a DataMapper::Collection < LazyArray and although it smells like an Array, you need to add your own proxy for something like to_json

LazyArray will not proxy the method "to_json" to the underlying array, because the JSON library auto-adds "to_json" to every object, so method_missing is never called. The fix is simple:

class LazyArray
  def to_json(*a)
    @array.to_json(*a)
  end
end

We do this when we initialize our framework, which is where I'm tempted to say it belongs -- but just wanted you guys to be aware as I'm sure it will raise a few wtf's if not documented, especially in Rails apps migrating to dm where render :json just works with AR collections.