# File lib/active_record/associations.rb, line 934
      def has_one(association_id, options = {})
        if options[:through]
          reflection = create_has_one_through_reflection(association_id, options)
          association_accessor_methods(reflection, ActiveRecord::Associations::HasOneThroughAssociation)
        else
          reflection = create_has_one_reflection(association_id, options)
          association_accessor_methods(reflection, HasOneAssociation)
          association_constructor_method(:build,  reflection, HasOneAssociation)
          association_constructor_method(:create, reflection, HasOneAssociation)
          configure_dependency_for_has_one(reflection)
        end
      end