class User < ActiveRecord::Base

  has_many :registries
  has_many :viewers
  has_many :registries, :through => :viewers

end

class Registry < ActiveRecord::Base

  belongs_to :user
  has_many :viewers
  has_many :users, :through => :viewers

end


class Viewer < ActiveRecord::Base

  belongs_to :user
  belongs_to :registry

end