Avoid N+1 queries with compose option

composed_preloading.rb

class User < ActiveRecord::Base
  # Only this class changed
  has_many :posts, compose: :published
end

class Post < ActiveRecord::Base
  belongs_to :user
  scope :published, -> { where(status: :published) }
end

User.limit(10).preload(:published_posts).each do |user|
  user.published_posts.each do |post|
    puts post.title
  end
end