Single Table Inheritance & Polymorphic Association in Rails 3

This is a Rails 3 Application that helps you to understand:

• Single Table Inheritance
• Polymorphic Associations

Single Table Inheritance

Example Taking "Mobile" as a single entity. We have Nokia, Samsung, Apple etc that will inherit the property of Mobile class.

class Mobile < ActiveRecord::Base end;

class Samsung < Mobile end; class Apple < Mobile end; class Macromax < Mobile end;

• config/routes.rb resources :mobiles resources :samsung, :controller => 'mobiles', :type => "Samsung" resources :apple, :controller => 'mobiles', :type => "Apple" resources :htc, :controller => 'mobiles', :type => "HTC" resources :macromax, :controller => 'mobiles', :type => "Macromax"

Polymorphic Associations

class Users < ActiveRecord::Base has_many :comments, :as => :commendable end

class Event < ActiveRecord::Base has_many :comments, :as => :commendable end

class Comment < ActiveRecord::Base belongs_to :commendable, :polymorphic => true end