Rails: if has_many relationship changed

Question

I\'ve got these two classes.

class Article < ActiveRecord::Base
  attr_accessible :body, :issue, :name, :page, :image, :video, :brand_ids
  has_many :pub         


        

Answer 1

Use the after_add and after_remove association callbacks to check for additions/removals along with using saved_changes? to check for any changes on existing articles.

class Doc < ActiveRecord::Base
  has_many :articles, after_add: :set_article_flag, after_remove: :set_article_flag

  after_save :do_something_with_changed_articles

  private

  def set_article_flag
    @articles_changed = true
  end

  def do_something_with_changed_articles
    if @articles_changed || articles.any?(&:saved_changes?)
      # do something
    end
  end
end