ruby-on-rails - 如何使用葡萄实体公开关联记录

Question

嗨，我有一个模型Event，这个活动有一个Setting。例如

class Event < ActiveRecord::Base
  has_one :setting
end

class Setting < ActieRecord::Base
  belongs_to :event
end

我的事件实体看起来像

module Entities
    class EventEntity < Grape::Entity
      expose :id
      expose :name, documentation: { type: String, desc: "Event name", required: true}
      expose :setting, using: Entities::EventSettingEntity
    end
end

我的EventSettingEntity课看起来像

module Entities
  class EventSettingEntity < Grape::Entity
    expose :id, :event_id
    expose :type, documentation: { type: String, desc: "Type" }
  end
end

我的 Api 就像

desc 'Create an event.' ,{
        params: Entities::EventEntity.documentation, type: :create
}
post 'create' do
  event = Event.create(params)
  present event, with: EventEntity
end

但主要问题是事件创建表单没有显示setting类type字段。请帮我解决问题。谢谢