ActiveModel::Serializer for ActiveModel::Model

active_model_serializer_for_activemodel.rb

# ActiveModel::SerializerをActiveModel::Modelで使う

class Model < ApplicationRecord
end

# Modelの操作をするクラス
class Dummy
  include ActiveModel::Serialization
  include ActiveModel::Model
  attr_accessor :model
  def model
    @model ||= Model.new
  end
end

class ModelSerializer < ActiveModel::Serializer
  attributes :id, :state
end

# Dummyオブジェクト用のシリアライザ
class DummySerializer < ActiveModel::Serializer
  # attributesのmodelをModelSerializerを通す。
  has_one :model
end


a = Dummy.new
b = ModelSerializer.new(a)
b.to_json
=> "{\"model\":{\"id\":\"f7e80d4a-be60-4475-897e-4ae47132b4b1\",\"state\":0}}"

b.as_json
=> {:model=>{:id=>"f7e80d4a-be60-4475-897e-4ae47132b4b1", :state=>0}}