rails--rails/activemodel/lib/active_model/attributes.rb

# frozen_string_literal: true

require "active_model/attribute_set"
require "active_model/attribute/user_provided_default"

module ActiveModel
  module Attributes #:nodoc:
    extend ActiveSupport::Concern
    include ActiveModel::AttributeMethods

    included do
      attribute_method_suffix "="
      class_attribute :attribute_types, :_default_attributes, instance_accessor: false
      self.attribute_types = Hash.new(Type.default_value)
      self._default_attributes = AttributeSet.new({})
    end

    module ClassMethods
      def attribute(name, type = Type::Value.new, **options)
        name = name.to_s
        if type.is_a?(Symbol)
          type = ActiveModel::Type.lookup(type, **options.except(:default))
        end
        self.attribute_types = attribute_types.merge(name => type)
        define_default_attribute(name, options.fetch(:default, NO_DEFAULT_PROVIDED), type)
        define_attribute_method(name)
      end

      private

        def define_method_attribute=(name)
          safe_name = name.unpack1("h*")
          ActiveModel::AttributeMethods::AttrNames.set_name_cache safe_name, name

          generated_attribute_methods.module_eval <<-STR, __FILE__, __LINE__ + 1
            def __temp__#{safe_name}=(value)
              name = ::ActiveModel::AttributeMethods::AttrNames::ATTR_#{safe_name}
              write_attribute(name, value)
            end
            alias_method #{(name + '=').inspect}, :__temp__#{safe_name}=
            undef_method :__temp__#{safe_name}=
          STR
        end

        NO_DEFAULT_PROVIDED = Object.new # :nodoc:
        private_constant :NO_DEFAULT_PROVIDED

        def define_default_attribute(name, value, type)
          self._default_attributes = _default_attributes.deep_dup
          if value == NO_DEFAULT_PROVIDED
            default_attribute = _default_attributes[name].with_type(type)
          else
            default_attribute = Attribute::UserProvidedDefault.new(
              name,
              value,
              type,
              _default_attributes.fetch(name.to_s) { nil },
            )
          end
          _default_attributes[name] = default_attribute
        end
    end

    def initialize(*)
      @attributes = self.class._default_attributes.deep_dup
      super
    end

    def attributes
      @attributes.to_hash
    end

    private

      def write_attribute(attr_name, value)
        name = if self.class.attribute_alias?(attr_name)
          self.class.attribute_alias(attr_name).to_s
        else
          attr_name.to_s
        end

        @attributes.write_from_user(name, value)
        value
      end

      def attribute(attr_name)
        name = if self.class.attribute_alias?(attr_name)
          self.class.attribute_alias(attr_name).to_s
        else
          attr_name.to_s
        end
        @attributes.fetch_value(name)
      end

      # Handle *= for method_missing.
      def attribute=(attribute_name, value)
        write_attribute(attribute_name, value)
      end
  end

  module AttributeMethods #:nodoc:
    AttrNames = Module.new {
      def self.set_name_cache(name, value)
        const_name = "ATTR_#{name}"
        unless const_defined? const_name
          const_set const_name, -value
        end
      end
    }
  end
end