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Namespaced models

31 May 2011

Guo Lei (guolei9@gmail.com)

When the application grows bigger, it's kinda messy to keep all the models under app/models. To make the codes more readable, it makes sense to use namespaced models.

1. Add customized directories to autoload_paths

You can add as many directories as you like and then ask Rails to load the files by adding them to autoload_paths (load_paths in Rails2).

  # config/application.rb
  class Application < Rails::Application
    config.autoload_paths += %W(#{Rails.root}/app/models/pets)
  end

Now you can have dog.rb, cat.rb & any_animal_you_like.rb inside /app/models/pets directory. Notice that the directory name can not be the same with any model's name. Otherwise there will be wired exceptions.

2. Put subclasses under a module

We all know the magic of "type" attribute. From how it works, we rarely need to call the subclass directly, so it will not cause inconvenience if we put the subclasses under a module.

# app/models/account.rb
class Account < ActiveRecord::Base
end

# app/models/user/student.rb
class User::Student < Account
end

# app/models/user/admin.rb
class User::Admin < Account
end

In most cases, you will use Account.find(id) to get a user instance. So although the name "User::Student" is a bit longer than "Student", it will not cause much trouble but more meaningful, as well as keeping the app/models folder clear.

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