Rails Polymorphic associations explained

gistfile1.rb

class User < ActiveRecord::Base
  attr_accessible :email, :name
  has_many :comments, :as => :commendable
end

class Event < ActiveRecord::Base
  attr_accessible :name, :organizer, :place
  has_many :comments, :as => :commendable
end

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

# Migration: create_comments.rb
class CreateComments < ActiveRecord::Migration
  def change
    create_table :comments do |t|
      t.text :comment
    t.references :commendable, :polymorphic => true
      t.timestamps
    end
  end
end