Rails 3 scope only select certain attributes for a has_many relationship-Collection of common programming errors

This looks like it should be something pretty easy but I can’t seem to get it to work. I have a model with a has_many relationship and I’d like a scope on the parent that allows me to select only certain attributes for each.

An example:

class Bakery < ActiveRecord::Base
  has_many :pastries
  scope :summary, select([:id, :name, 'some option calling pastries.summary'])

class Pastry < ActiveRecord::Base
  belongs_to :bakery
  scope :summary, select([:id, :image_url])

I’d like to be able to call something like Bakery.first.summary and get a Bakery model with only the id and name populated and for each pastry in it’s pastries array to only have the id and image_url attributes populated.