Organize Serializer concerns into concerns/

lib/active_model/serializer/concerns/attributes.rb

@@ -0,0 +1,82 @@
+module ActiveModel
+  class Serializer
+    module Attributes
+      extend ActiveSupport::Concern
+
+      included do
+        with_options instance_writer: false, instance_reader: false do |serializer|
+          serializer.class_attribute :_attributes_data # @api private
+          self._attributes_data ||= {}
+        end
+
+        extend ActiveSupport::Autoload
+        autoload :Attribute
+
+        # Return the +attributes+ of +object+ as presented
+        # by the serializer.
+        def attributes(requested_attrs = nil, reload = false)
+          @attributes = nil if reload
+          @attributes ||= self.class._attributes_data.each_with_object({}) do |(key, attr), hash|
+            next if attr.excluded?(self)
+            next unless requested_attrs.nil? || requested_attrs.include?(key)
+            hash[key] = attr.value(self)
+          end
+        end
+      end
+
+      module ClassMethods
+        def inherited(base)
+          super
+          base._attributes_data = _attributes_data.dup
+        end
+
+        # @example
+        #   class AdminAuthorSerializer < ActiveModel::Serializer
+        #     attributes :id, :name, :recent_edits
+        def attributes(*attrs)
+          attrs = attrs.first if attrs.first.class == Array
+
+          attrs.each do |attr|
+            attribute(attr)
+          end
+        end
+
+        # @example
+        #   class AdminAuthorSerializer < ActiveModel::Serializer
+        #     attributes :id, :recent_edits
+        #     attribute :name, key: :title
+        #
+        #     attribute :full_name do
+        #       "#{object.first_name} #{object.last_name}"
+        #     end
+        #
+        #     def recent_edits
+        #       object.edits.last(5)
+        #     end
+        def attribute(attr, options = {}, &block)
+          key = options.fetch(:key, attr)
+          _attributes_data[key] = Attribute.new(attr, options, block)
+        end
+
+        # @api private
+        # keys of attributes
+        # @see Serializer::attribute
+        def _attributes
+          _attributes_data.keys
+        end
+
+        # @api private
+        # maps attribute value to explict key name
+        # @see Serializer::attribute
+        # @see FragmentCache#fragment_serializer
+        def _attributes_keys
+          _attributes_data
+            .each_with_object({}) do |(key, attr), hash|
+              next if key == attr.name
+              hash[attr.name] = { key: key }
+            end
+        end
+      end
+    end
+  end
+end