You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: base.rb
    path of file: ./repos/coursemology2/lib/extensions/materials/active_record
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
module Extensions::Materials::ActiveRecord::Base
  module ClassMethods
    # Declare this to allow 
    
    def has_one_folder # rubocop:disable Naming/PredicateName
      after_initialize :build_new_record_folder, if: :new_record?

      has_one :folder, as: :owner, class_name: Course::Material::Folder.name,
                       inverse_of: :owner, dependent: :destroy, autosave: true
      has_many :materials, through: :folder, class_name: Course::Material.name

      include Extensions::Materials::ActiveRecord::Base::InstanceMethods
    end