用事件挂钩观察者

Question

我们在很多模型中使用 AASM，但我们正在考虑稍微简化模型。我们想做的一件事是将所有通知内容从模型中移出并放入观察者中。

所以考虑一下：

class ClarificationRequest < ActiveRecord::Base
  include AASM

  aasm_initial_state :open

  # States
  aasm_state :open
  aasm_state :closed

  # Events
  aasm_event :close, :after => :notify_closed do transitions :to => :closed, :from => [:open,:replied], :guard => :can_close? end
end

我已经尝试过这个，但没有运气：

class ClarificationRequestObserver < ActiveRecord::Observer
  observe :clarification_request

  def after_close
    puts '############### message from observer!!!!!'
  end
end

如何将 :notify_close 移动到观察者？

谢谢！

.卡里姆

Answer 1

我之前在github上回复过你的评论，我在这里重复一下，以防万一

class ClarificationRequest < ActiveRecord::Base
    include AASM

    aasm_initial_state :open

    # States
    aasm_state :open
    aasm_state :closed

    # Events
    aasm_event :close, :after => :notify_closed do transitions :to => :closed, :from => [:open,:replied], :guard => :can_close? end

    # Notify Observer
    def notify_closed
     notify :close # this will trigger after_close method call in ClarificationRequestObserver
     # notify :closed # this will trigger after_closed method call in ClarificationRequestObserver
     # notify :whatever # this will trigger after_whatever method call in ClarificationRequestObserver
    end
end

Answer 2

说实话，我觉得你过得很好。对于这样的事情使用 AASM 钩子是有意义的。这样您就知道它已转换正常，然后您发送通知。

您可以查看在 before_update 中使用活动记录 dirty 来检查 state_ 是否已打开且现在已关闭。

Answer 3

我会做这样的事情：

class ClarificationRequest < ActiveRecord::Base
  include AASM

  aasm_initial_state :open

  # States
  aasm_state :open
  aasm_state :closed, :enter => :do_close

  # Events
  aasm_event :close do transitions :to => :closed, :from => [:open,:replied], :guard => :can_close? end

  def recently_closed?
    @recently_closed
  end 
protected
  def do_close
    @recently_closed = true
  end

end


class ClarificationRequestObserver < ActiveRecord::Observer
  observe :clarification_request

  def after_save(clarification_request)
    puts '############### message from observer!!!!!' if clarification_request.recently_closed?
  end
end

您还应该将观察者包含在 config/environment.rb 的 config.active_record.observers 列表中

原因是观察者应该观察一个对象。通过主动通知模型中的观察者（并与之交互），您假设有一个可用的观察者，但我不认为您可以安全地做到这一点（看看观察者通常在现实世界中的行为方式）。观察者是否对事件感兴趣应该由观察者决定。