Rails enum

ar_5_enum.rb

# File activerecord/lib/active_record/enum.rb, line 146
# https://github.com/rails/rails/blob/919a876a04d991bb5a984314ca985168cfbbbef5/activerecord/lib/active_record/enum.rb#L146
# rails 5 backport so we can get the _prefix and _suffix features

if Rails::VERSION::MAJOR < 5
  module ActiveRecord
    module Enum
      def enum(definitions)
        klass = self
        enum_prefix = definitions.delete(:_prefix)
        enum_suffix = definitions.delete(:_suffix)
        definitions.each do |name, values|
          # statuses = { }
          enum_values = ActiveSupport::HashWithIndifferentAccess.new
          name        = name.to_sym

          # def self.statuses() statuses end
          detect_enum_conflict!(name, name.to_s.pluralize, true)
          klass.singleton_class.send(:define_method, name.to_s.pluralize) { enum_values }

          _enum_methods_module.module_eval do
            # BEGIN from Rails 4 http://apidock.com/rails/v4.2.7/ActiveRecord/Enum/enum
            # def status=(value) self[:status] = statuses[value] end
            klass.send(:detect_enum_conflict!, name, "#{name}=")
            define_method("#{name}=") { |value|
              if enum_values.has_key?(value) || value.blank?
                self[name] = enum_values[value]
              elsif enum_values.has_value?(value)
                # Assigning a value directly is not a end-user feature, hence it's not documented.
                # This is used internally to make building objects from the generated scopes work
                # as expected, i.e. +Conversation.archived.build.archived?+ should be true.
                self[name] = value
              else
                raise ArgumentError, "'#{value}' is not a valid #{name}"
              end
            }

            # def status() statuses.key self[:status] end
            klass.send(:detect_enum_conflict!, name, name)
            define_method(name) { enum_values.key self[name] }

            # def status_before_type_cast() statuses.key self[:status] end
            klass.send(:detect_enum_conflict!, name, "#{name}_before_type_cast")
            define_method("#{name}_before_type_cast") { enum_values.key self[name] }
            # END from Rails 4 http://apidock.com/rails/v4.2.7/ActiveRecord/Enum/enum

            pairs = values.respond_to?(:each_pair) ? values.each_pair : values.each_with_index
            pairs.each do |value, i|
              if enum_prefix == true
                prefix = "#{name}_"
              elsif enum_prefix
                prefix = "#{enum_prefix}_"
              end
              if enum_suffix == true
                suffix = "_#{name}"
              elsif enum_suffix
                suffix = "_#{enum_suffix}"
              end

              value_method_name = "#{prefix}#{value}#{suffix}"
              enum_values[value] = i

              # def active?() status == 0 end
              klass.send(:detect_enum_conflict!, name, "#{value_method_name}?")
              define_method("#{value_method_name}?") { self[name] == i }

              # def active!() update! status: :active end
              klass.send(:detect_enum_conflict!, name, "#{value_method_name}!")
              define_method("#{value_method_name}!") { update! name => value }

              # scope :active, -> { where status: 0 }
              klass.send(:detect_enum_conflict!, name, value_method_name, true)
              klass.scope value_method_name, -> { klass.where name => i }
            end
          end
          defined_enums[name.to_s] = enum_values
        end
      end
    end
  end
else
  ActiveSupport::Deprecation.warn("Can remove Enum backport since we are on Rails 5 now.")
end