为什么会有一个nomethod错误?

I call this method in my controller:

我在控制器中调用这个方法:

delete_heard_timeline_event(current_user.id, @showable_video.user.id, @showable_video.video.id)

and I definite it in my model:

我在我的模型中确定了它:

  def delete_heard_timeline_event(actor_id, subject_id, secondary_subject_id)
      TimelineEvent.find_by_actor_id_and_subject_id_and_secondary_subject_id_and_event_type(actor_id, subject_id, secondary_subject_id, 'heard_event').destroy
  end

Why is rails telling me that the method is undefined?

为什么rails告诉我这个方法没有定义?

2 个解决方案

#1

If you defined this method as instance method so you need to to call it like this:

如果您将此方法定义为实例方法，那么您需要这样称呼它:

a = YourModelName.new
a.delete_heard_timeline_event(your_parameters)

and if this methods is class method so call:

如果这个方法是类方法，那么调用:

YourModelName.delete_heard_timeline_event(your_parameters)

#2

I see there is already accepted answer, but to answer to your question:

我看到已经有人接受了答案，但要回答你的问题:

if this NoMethodError pops out because of this line:

如果这个NoMethodError因为这条线弹出:

find_by_actor_id_and_subject_id_and_secondary_subject_id_and_event_type

I think Rails can handle max 3 conditions and you have 4 there.

我认为Rails可以处理最多3个条件，这里有4个。

And because you are in Rails 3, you could do it like this:

因为你在Rails 3中，你可以这样做:

class TimelineEvent
  def self.delete_heard_event(actor_id, subject_id, sec_id)
    self.scoped.where(:actor_id => actor_id,
     :subject_id => subject_id,
     :secondary_subject_id => sec_id,
     :event_type => 'heard_event').first.try(:destroy)
  end
end

The .try method at the end tries to fire a method in it's parameter, but only on non-nil objects, so you are safe to call it with wrong parameters.

最后的.try方法尝试在它的参数中触发一个方法，但是只在非nil对象上使用，所以您可以安全地调用错误的参数。

Then just:

然后:

TimelineEvent.delete_heard_event(current_user.id, @showable_video.user.id, @showable_video.video.id)

Regards, NoICE

问候,吵

#1