Rails Active Model Serializer - has_many并访问父记录

Question

我正在尝试使用Active Model Serializer构建一些Rails模型的JSON表示,其中一些模型嵌入了其他模型.例如,我有Event和Attendees,Event has_and_belongs_to_many Attendees.

class EventSerializer < ActiveModel::Serializer
  attributes :name

  has_many :attendees, serializer: AttendeeSerializer
end

class AttendeeSerializer < ActiveModel::Serializer
  attributes :name
end

这会导致JSON之类的{ name: 'Event One', attendees: [{ name: 'Alice' }, { name: 'Bob' }] }.

现在,我想补充与会者对此次活动所说的内容.让我们说,评论belongs_to事件,belongs_to参加者.我想在事件的序列化输出中包含所述注释,因此它会成为{ name: 'Event One', attendees: [{ name: 'Alice', comments: [{ text: 'Event One was great!'}] }, { name: 'Bob', comments: [] }] }.

我本可以有

class AttendeeSerializer < ActiveModel::Serializer
  attributes :name

  has_many :comments
end

但这会选择此与会者对所有活动的所有评论 - 而不是我想要的.我想写这个,但是如何找到我正在进行序列化的特定事件？我可以以某种方式访问​​'父'对象,或者可能将选项传递给has_many序列化程序？

class AttendeeSerializer < ActiveModel::Serializer
  attributes :name

  has_many :comments

  def comments
    object.comments.where(event_id: the_event_in_this_context.id)
  end
end

这是可以完成的事情,还是我应该以另一种方式为这个特定的用例构建JSON？

Answer 1

我会手动做事来控制:

class EventSerializer < ActiveModel::Serializer
  attributes :name, :attendees

  def attendees
    object.attendees.map do |attendee|
      AttendeeSerializer.new(attendee, scope: scope, root: false, event: object)
    end
  end
end

class AttendeeSerializer < ActiveModel::Serializer
  attributes :name, :comments

  def comments
    object.comments.where(event_id: @options[:event].id).map do |comment|
      CommentSerializer.new(comment, scope: scope, root: false)
    end
  end
end