[Beginning Rails 6] Listing 6-32. The email_article_author Method Specified as an after_create Callback in app/models/comment.rb

comment.rb

class Comment < ApplicationRecord
  belongs_to :article

  validates :name, :email, :body, presence: true
  validate :article_should_be_published

  after_create :email_article_author

  def article_should_be_published
    errors.add(:article_id, 'is not published yet') if article && !article.published?
  end

  def email_article_author
    puts "We will notify #{article.user.email} in Chapter 12" if article.user
  end
end