election_models.rb

# Voter, the polymorphic model
class Voter < ActiveRecord::Base
  belongs_to :voterable, polymorphic: true

  has_many :votes
  has_many :candidates, through: :votes
end

# Citizen, has one voter as voterable
# this is a new model where many of the attributes 
# that a voter has would move to
class Citizen < ActiveRecord::Base
  has_one :voter, as: :voterable
end

# Candidate, has one voter as voterable
# this was interesting, I wasn't sure if ActiveRecord would allow a model to
# have_many of a model and have_one of the same model.  Turns out it can.
# candidate.voters will be a method as well as a candidate.voter
#
# I added a method #as_a_voter, which aliases the #voter method
# that ActiveRecord provides to, hopefully, lessen confusion and 
# make the interface more legible
class Candidate < ActiveRecord::Base
  has_one :voter, as: :voterable

  has_many :votes
  has_many :voters, through: :votes
  
  def as_a_voter
    self.voter  
  end
end

# Vote, nothing here has changed
class Vote < ActiveRecord::Base
  belongs_to :voter
  belongs_to :candidate
end