I have a card-game application which makes use of Single Table Inheritance. I have a class Card, and a database table cards with column type, and a number of subclasses of Card (including class Foo < Card and class Bar < Card, for the sake of argument).

As it happens, Foo is a card from the original printing of the game, which Bar is a card from an expansion. In an attempt to rationalise my models, I have created a directory structure like so:

app/
+ models/
  + card.rb
  + base_game/
    + foo.rb
  + expansion/
    + bar.rb

And modified environment.rb to contain:

Rails::Initializer.run do |config|
  config.load_paths += Dir["#{RAILS_ROOT}/app/models/**"]
end

However, when my reads a card from the database, Rails throws the following exception:

ActiveRecord::SubclassNotFound (The single-table inheritance mechanism failed to locate the subclass: 'Foo'. This error is raised because the column 'type' is reserved for storing the class in case of inheritance. Please rename this column if you didn't intend it to be used for storing the inheritance class or overwrite Card.inheritance_column to use another column for that information.)

Is it possible to make this work, or am I doomed to a flat directory structure?