README.md

irb(main):029:0* GeoEntity.last

GeoEntity Load (0.5ms) SELECT geo_entities.* FROM geo_entities ORDER BY geo_entities.id DESC LIMIT 1

returns:

County id: 4, eid: nil, pid: nil, ename: nil, etype: 2, created_at: "2011-11-21 06:26:37", updated_at: "2011-11-21 06:26:37"

city.rb

class City < GeoEntity
end

county.rb

class County < GeoEntity
end

geo_entity.rb

class GeoEntity < ActiveRecord::Base
  set_inheritance_column :etype

  ENTITIES = {
    1 => GeoEntity::State,
    2 => GeoEntity::County,
    3 => GeoEntity::City,
    4 => GeoEntity::Zip
  }

  class << self
    def find_sti_class(type_name)
      ENTITIES[type_name.to_i] or super
    end

    def sti_name
      ENTITIES.invert[self]
    end
  end


end

state.rb

class State < GeoEntity
end

zip.rb

class Zip < GeoEntity
end