rails4 sti, custom "type" column name and value

city.rb

class City < GeoEntity

  def self.sti_name
    3
  end  

end

county.rb

class Country < GeoEntity

  def self.sti_name
    2
  end  

end

geo_entity.rb

class GeoEntity < ActiveRecord::Base
  self.inheritance_column = 'etype'

  def self.find_sti_class(type_name)
    type_name = self.name # so GeoEntity.new(etype: 2) returns Country
    self
  end
  
end

state.rb

class State < GeoEntity

  def self.sti_name
    1
  end  

end

zip.rb

class Zip < GeoEntity

  def self.sti_name
    4
  end  
  
end