管理课程招生

Question

我已经写了一些代码来暂停某个课程的注册。一个课程可能有多个演示文稿。

module Enrolments
  class Suspend
    attr_reader :enrolment, :responses, :comment, :user_id
    attr_writer :event_service, :suspend_enrolment_presentation_service

    def initialize
      @responses = []
    end

    def call(enrolment, user_id, comment)
      @enrolment = enrolment
      @user_id = user_id
      @comment = comment

      suspend_enrolment_presentations
      if all_enrolment_presentations_suspended?
        suspend_enrolment
        raise_suspended_enrolment_event
        create_enrolment_comment
      end
    end

    private

    attr_reader :response

    def suspend_enrolment_presentations
      enrolment.enrolment_presentations.each do |ep|
        @responses << suspend_enrolment_presentation_service.call(ep)
      end
    end

    def all_enrolment_presentations_suspended?
      @responses.all?{ |r| r[:success] }
    end

    def suspend_enrolment
      enrolment.status = 'Suspended'
      enrolment.save
    end

    def raise_suspended_enrolment_event
      event_service.call(enrolment)
    end

    def create_enrolment_comment
      EnrolmentComment.create(comment: comment, user_id: user_id, enrolment_id: enrolment.id)
    end

    def event_service
      @event_service ||= Events::Outgoing::Enrolments::SuspendedEnrolment.new
    end

    def suspend_enrolment_presentation_service
      @suspend_enrolment_presentation_service ||= Enrolments::EnrolmentPresentations::Suspend.new
    end
  end
end

代码是相当直接的。它有两个依赖项，它们在测试时通过attr_writers注入，否则在访问时被实例化。

我听过/读过许多关于回调的问题。这段代码的问题在于，如果我只想暂停注册，而不想引发事件或创建注释，我就不能。一些解决方法是使用装饰模式，或者我想我可以组合和对象所有的服务，并管理其中的所有内容。

我真的在我的代码中为SRP和好的设计而奋斗。我非常感谢任何关于如何改进这段代码的意见。我是否应该将代码提取到更高的抽象级别，并将其处理得更高一级呢？如果运行一段代码取决于另一段代码的传递怎么办？如果我要将它提取出来，它将在我的控制器中着陆，这是我所能达到的高度，除非我随后将它提取到一个表单对象中。

Answer 1

在我看来，原来的课正在打破SRP，所以我决定把这个班分成两个班。一个处理当暂停发生时需要发生的事情的协调。这允许我只包含注册者的实际暂停逻辑：：挂起和任何其他必需的回调都被放入协调器。这样，每个类都应该只有一个改变的理由。

module Enrolments
  class SuspendCoordinator
    attr_reader :enrolment, :comment
    attr_writer :event_service, :suspend_enrolment_service

    def call(enrolment, comment)
      @enrolment = enrolment
      @comment = comment

      if suspend_enrolment
        raise_suspended_enrolment_event
        create_enrolment_comment
      end
    end

    private

    attr_reader :responses

    def suspend_enrolment
      suspend_enrolment_service.call(enrolment)
    end

    def raise_suspended_enrolment_event
      event_service.call(enrolment)
    end

    def create_enrolment_comment
      EnrolmentComment.create(comment: comment, user_id: RequestRegistry.current_user.id, enrolment_id: enrolment.id)
    end

    def suspend_enrolment_service
      @suspend_enrolment_service ||= Enrolments::Suspend.new
    end

    def event_service
      @event_service ||= Events::Outgoing::Enrolments::SuspendedEnrolment.new
    end
  end
end

module Enrolments
  class Suspend
    attr_reader :enrolment, :responses, :comment, :user_id
    attr_writer :suspend_enrolment_presentation_service

    def initialize
      @responses = []
    end

    def call(enrolment)
      @enrolment = enrolment

      suspend_enrolment_presentations
      suspend_enrolment if all_enrolment_presentations_suspended?
    end

    private

    attr_reader :response

    def suspend_enrolment_presentations
      enrolment.enrolment_presentations.each do |ep|
        @responses << suspend_enrolment_presentation_service.call(ep)
      end
    end

    def suspend_enrolment
      enrolment.status = 'Suspended'
      enrolment.save
    end

    def all_enrolment_presentations_suspended?
      @responses.all?{ |r| r[:success] }
    end

    def suspend_enrolment_presentation_service
      @suspend_enrolment_presentation_service ||= Enrolments::EnrolmentPresentations::Suspend.new
    end
  end
end