如何使用葡萄实体公开相关记录

Question

您好我有一个模型Event，此活动有一个Setting。 e.g

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课程类似于

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未显示setting类type字段。请帮我解决这个问题。感谢