Rails as_json issue - How to include nested objects efficiently?

I'm running into an issue where I'm working with the as_json method, and how to efficiently return the object in JSON AND it's belongs_to object as JSON as well, where the belongs_to object has its own belongs_to object. Code would probably explain it better.

The Not-Working Way

Alert class

class Alert < ActiveRecord::Base
    belongs_to :message
    # for json rendering
    def as_json(options={})
        super(:include => :message)
    end
end

Message class

 def as_json(options={})
    super( methods: [:timestamp, :num_photos, :first_photo_url, :tag_names],
           include: { camera: { only: [:id, :name] },
                      position: { only: [:id, :name, :address, :default_threat_level ]},
                      images: { only: [:id, :photo_url, :is_hidden]} })
  end

The problem with this first set up is that when I have an Alert object and call

alert.as_json()

I get all the attributes from Alert and all the attributes from Message, but none of the other attributes from Message that I want, like Camera, Position, etc.

Here's the "It's Working, But Probably Not Proper Design Way"

Alert Class

class Alert < ActiveRecord::Base

    belongs_to :message

    # for json rendering
    def as_json(options={})
        super().merge(:message => message.as_json)
    end
end

Messages Class

  # for json rendering
  def as_json(options={})
    super( methods: [:timestamp, :num_photos, :first_photo_url, :tag_names])
          .merge(:camera => camera.as_json)
          .merge(:position => position.as_json)
          .merge(:images => images.as_json)
  end

In this 2nd setup, I get all of Messages's nested attributes like I want.

My question, am I missing some Rails C