identity.rb

class Identity < ActiveRecord::Base
  belongs_to :user
  has_many :accounts
  
  # relation logic methods.
end

class Account < ActiveRecord::Base
  belongs_to :identity
end

class TwitterAccount < Account
end

class FacebookAccount < Account
end

class YoutubeAccount < Account
end

class User < ActiveRecord::Base
  has_one :identity
  
  def aggregate_social_nonsense
    identity.aggregate_social_nonsense
  end
end

stages.rb

class BetterNameThanStageRelationForDescribingRelationshipBetweenIntakeAndStage < ActiveRecord::Base
  belongs_to :intake
  has_one :stage

  has_many :demos
  has_many :loans
  has_many :releases

  def each_by_date
    # To the best of my knowledge there's no Ruby that can interleave these as they come from the database.
    (demos.order_by(:date) + loans.order_by(:date) + releases.order_by(:date)).sort_by(&:date)
  end
end

class Intake < ActiveRecord::Base
  has_one :BetterNameThanStageRelationForDescribingRelationshipBetweenIntakeAndStages.underscored
end

class Demo < ActiveRecord::Base
  belongs_to :BetterNameThanStageRelationForDescribingRelationshipBetweenIntakeAndStages.underscored
end

class Loan < ActiveRecord::Base
  belongs_to :BetterNameThanStageRelationForDescribingRelationshipBetweenIntakeAndStages.underscored
end

class Release < ActiveRecord::Base
  belongs_to :BetterNameThanStageRelationForDescribingRelationshipBetweenIntakeAndStages.underscored
end