Rails and PostgreSQL inheritance

awesome_ad.rb

class AwesomeAd < ActiveRecord::Base;end

migration.rb

class CreateAds < ActiveRecord::Migration
  def up
    create_table "ads", :force => true do |t|
      t.decimal "uid",             :precision => 30, :scale => 0,                   :null => false
      t.string  "title",                                                            :null => false
    end

    create_table :my_cool_ads, options: 'INHERITS (ads)'
    create_table :awesome_ads, options: 'INHERITS (ads)'
  end

  def down
    drop_table :awesome_ads
    drop_table :my_cool_ads
    drop_table :ads
  end
end

my_cool_ad.rb

class MyCoolAd < ActiveRecord::Base;end

pg_inheritance_rails.rb

example_ids = [1, 2, 3, 4]

initialize_klasses = {}
result = ActiveRecord::Base.connection.execute(
  ActiveRecord::Base::sanitize_sql_array[%Q{
    SELECT distinct("ads".*), pg_class.relname
    FROM ads, pg_class
    WHERE ads.id IN (?)
      AND ads.tableoid = pg_class.oid
  }, example_ids
  ]).to_a
result.map do |attributes|
  object_attributes = attributes.reject { |key, _| key == 'relname' }
  klass = attributes['relname']
  initialize_klasses[klass] ||= klass.camelize.singularize.constantize

  object = initialize_klasses[klass].new object_attributes, without_protection: true
  object.instance_variable_set :'@new_record', false
  object
end