sti_update_attributes.rb

# STI, this is the base model which is stored in the database
class Character < ActiveRecord::Base
  belongs_to :location

  def move_to(new_location)
    update_attribute(:location_id, new_location.id)

    # or:
    # self.location = new_location
    # save
  end
end

class PlayerCharacter < Character
end

location_1 = Location.find(1)
location_2 = Location.find(2)

# Behold the following:
@player_character.location => location_1
@player_character.move_to(location_2) => true
@player_character.location => location_1 # Even after @player_character.reload

# This does work:
@player_character.location => location_1
@player_character.location = location_2
@player_character.save
@player_character.location => location_2