post.rb

post.rb

class Post < ActiveRecord::Base
  belongs_to :user
  belongs_to :topic, :counter_cache => true, :touch => :last_updated_at

  scope :major, where(:major=>true)
  scope :reply, where(:major=>false)

  validates_presence_of :body

  after_create  :update_cached_fields

  protected
    def update_cached_fields
      topic.update_cached_post_fields(self) unless self.major
    end
end