如何编写验证来确保现有关联在 Rails 3 中无法更改？

发布于 2024-11-08 11:22:18 字数 949 浏览 0 评论 0原文

我见过很多问题询问如何验证关联的存在，但这个问题有点复杂。

假设我有三个模型：一个 Plane、一个 Pilot 和一个 Flight。

一架飞机可以配备一名飞行员和一名航班。

一旦为飞机分配了飞行员，就可以为其分配航班。

我想编写一些验证代码，以确保一旦Plane同时拥有Flight和Pilot，Pilot 无法更改。 因此，我希望此测试能够通过：

describe Plane do
    context "before updating" do
        it "ensures that the pilot cannot be changed if the plane has any flights" do
            plane        = Plane.create!
            plane.pilot  = Pilot.create!
            plane.flight = Flight.create!

            hijacker = Pilot.create!
            plane.pilot = hijacker

            plane.save.should be_false
            plane.errors[:base].should include "Can't change the pilot while in-flight"
        end
    end
end

我希望了解可以使用哪些技术来实现此目的。谢谢大家！

原文

I have seen many questions asking how to validate the presence of an association, but this question is a bit more complex.

Say I have three models, a Plane, a Pilot, and a Flight.

A Plane can have one Pilot and one Flight.

Once a Plane has been assigned a Pilot, it can then be assigned a Flight.

I would like to write some validation code to ensure that once a Plane has both a Flight and a Pilot, the Pilot cannot be changed. So I would like this test to pass:

describe Plane do
    context "before updating" do
        it "ensures that the pilot cannot be changed if the plane has any flights" do
            plane        = Plane.create!
            plane.pilot  = Pilot.create!
            plane.flight = Flight.create!

            hijacker = Pilot.create!
            plane.pilot = hijacker

            plane.save.should be_false
            plane.errors[:base].should include "Can't change the pilot while in-flight"
        end
    end
end

I would love some insight as to what techniques are available to accomplish this. Thanks all!

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A君 2024-11-15 11:22:18

您可以从自定义验证开始，根据数据库中实际的基础记录检查更改的记录（位于内存中）。

class Plane < ActiveRecord::Base
  validate_on_update :pilot_cannot_be_changed

  def pilot_cannot_be_changed
    errors.add(:pilot, "cannot be changed while in-flight.") 
      if pilot.id != Plane.find(id).pilot.id
  end

You could start with a custom validation that checks the changed record (sitting in memory) against the underlying record that's actually in the database.

class Plane < ActiveRecord::Base
  validate_on_update :pilot_cannot_be_changed

  def pilot_cannot_be_changed
    errors.add(:pilot, "cannot be changed while in-flight.") 
      if pilot.id != Plane.find(id).pilot.id
  end

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清引 2024-11-15 11:22:18

您可以编写自己的验证来确保这一点..
但在你指派飞行员的那一刻，但在最后，当你拯救飞机时，这不会返回错误。

所以这里是更简单的版本：

class Plane < ActiveRecord::Base

  def pilot=(val)
    return false if self.pilot && self.flight
    @pilot = val
    # I'm not sure about this line above, you can use something like this (or both lines)
    # write_attribute(:pilot_id, val.id)
  end

end

希望这会有所帮助（或至少为您导航正确的方向）。

问候，诺斯

you can write your own validation to ensure this..
but that wouldn't return false to you in the moment you assign a pilot, but at the end, when you save the plane.

So here is simpler version:

class Plane < ActiveRecord::Base

  def pilot=(val)
    return false if self.pilot && self.flight
    @pilot = val
    # I'm not sure about this line above, you can use something like this (or both lines)
    # write_attribute(:pilot_id, val.id)
  end

end

Hope this helps (or at least navigate you the right direction).

Regards, NoICE

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