Callbacks and the Active Record

We’ve made a lot of changes to our models, so let’s make sure we’re on the same page before we move on. First, take a look at the Event model in Listing 5-27 and make sure that yours matches.

Listing 5-27. Current Event Model, in /app/models/event.rb

class Event < ActiveRecord::Base
  belongs_to :user
  has_many :registrations
  has_many :attendees, :through => :registrations, :source => :user 
  has_and_belongs_to_many :categories

  validates_presence_of :title, :location

  after_create :ensure_owner_attends
  validate     :has_not_occurred

  def is_in_the_past?
    occurs_on < Date.today
  end

  def long_title
    "#{title} - #{location} - #{occurs_on}"
  end

  protected
    def ensure_owner_attends
      unless attendees.include? user
        attendees << user
      end
  end

  def has_not_occurred
    errors.add("occurs_on", "is in the past") if occurs_on && is_in_the_past?
  end
end