Rails - Oct 2009 - Inheritance Problem

Hello.

I have a question to inheritance in Rails(2.3.4).

I have this three models.

class Vehicle < ActiveRecord::Base
end

class Car < Vehicle
end

class RallyCar < Car
end

And this Migration:
class CreateVehicles < ActiveRecord::Migration
  def self.up
    create_table :vehicles do |t|
      t.string :name
      t.string :brand
      t.string  :type
      t.timestamps
    end

    Vehicle.create(:name =>''Demo Vehicle'', :brand =>
''unknown'')
    Vehicle.create(:name => ''Demo2 Vehicle'', :brand =>
''unknown'')
    Car.create(:name => ''My Car'', :brand =>
''Mercedes'')
    Car.create(:name => ''My Second Car'', :brand =>
''VW'')
    RallyCar.create(:name => ''My Rally Car'', :brand =>
''Ford'')
    RallyCar.create(:name => ''My Second Rally Car'', :brand
=> ''Toyota'')
  end

  def self.down
    drop_table :vehicles
  end
end


This model structur has curious behavior.
>> Vehicle.count
=> 6
>> Car.count
=> 2
>> RallyCar.count
=> 2
>> Car.count
=> 4

I have the same Problem in find.
Car.find(:all) returns two Records
RallyCar.count
Car.find(:all) returns four Records

Can anyone help me.

Thanks,
Michael
-- 
Posted via http://www.ruby-forum.com/.

On Oct 24, 11:07 am, "Michael .."
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> I have the same Problem in find.
> Car.find(:all) returns two Records
> RallyCar.count
> Car.find(:all) returns four Records
>
This is  a known pecularity of STI - when you do a count for the
subclass it adds a type = "Car" condition. This obviously
doesn''t find
instances of RallyCar. Once the RallyCar class is loaded then
ActiveRecord is aware of its existance and will add type = "Car" or
type = "RallyCar" as the condition. It''s a bit messy but in
production
it should work fine (since all classes are loaded up front) or you can
also use require_dependency to force them to be loaded (ie at the
bottom of car.rb stick require_dependency ''rally_car'')

Fred
> Can anyone help me.
>
> Thanks,
> Michael
> --
> Posted viahttp://www.ruby-forum.com/.