From https://once.com/writebook

app/models/book.rb

@@ -0,0 +1,15 @@
+class Book < ApplicationRecord
+  include Accessable, Sluggable
+
+  has_many :leaves, dependent: :destroy
+  has_one_attached :cover, dependent: :purge_later
+
+  scope :ordered, -> { order(:title) }
+  scope :published, -> { where(published: true) }
+
+  enum :theme, %w[ black blue green magenta orange violet white ].index_by(&:itself), suffix: true, default: :blue
+
+  def press(leafable, leaf_params)
+    leaves.create! leaf_params.merge(leafable: leafable)
+  end
+end