From https://once.com/writebook

app/models/leaf.rb

@@ -0,0 +1,15 @@
+class Leaf < ApplicationRecord
+  include Editable, Positionable
+
+  belongs_to :book, touch: true
+  delegated_type :leafable, types: Leafable::TYPES, dependent: :destroy
+  positioned_within :book, association: :leaves, filter: :active
+
+  enum :status, %w[ active trashed ].index_by(&:itself), default: :active
+
+  scope :with_leafables, -> { includes(:leafable) }
+
+  def slug
+    title.parameterize.presence || "-"
+  end
+end