Rails：如何使用before_save更改基于另一个字段的字段值？ [英] Rails: How to use before_save to change a field value based on another field?

问题描述

我正在尝试根据另一个布尔字段的值将布尔字段设置为false。我用ActiveRecord模型尝试了以下操作：

I'm trying to set a boolean field to false based on the value of another boolean field. I tried the following with an ActiveRecord model:

  before_save :reconcile_xvent

  def reconcile_xvent
    self.xvent_hood = false if !self.xvent_plenum?
  end

但这是行不通的。现在，我的许多单元测试都失败了：

But this doesn't work. Now, many of my unit tests fail with:

ActiveRecord::RecordNotSaved: ActiveRecord::RecordNotSaved

如果xvent_plenum为假，如何将xvent_hood设置为假？

How can I set xvent_hood to be false if xvent_plenum is false?

更新

有效的方法（其中一些来自下面的评论/答案）：

Here's what works (some of which comes from the comments/answers below):

before_validation :reconcile_xvent

def reconcile_xvent
  if self.xvent_hood?
    self.xvent_hood = false unless xvent_plenum?
  end
end

我不知道要不让它起作用如果self.xvent_hood？部分...。

I couldn't figure out to make it work without the "if self.xvent_hood?" part....

推荐答案

before_save 仅 在验证通过后调用。您需要做的是将 reconcile_xvent 移至 before_validation 而不是 before_save

before_save is only called after validation has passed. What you need to do is move reconcile_xvent up to before_validation rather than before_save

如果将该方法保留在 before_save 中，将会发生的事情是它认为 xvent_hood 为空，如果您具有用于验证 xvent_hood 的无效性的验证，它将在 before_save <之前失败。 / code>被调用。这可能解释了为什么您出现 RecordNotSaved 错误。

If you keep that method in before_save what will happen is that it thinks that xvent_hood is null, if you have a validation that checks for nullity of xvent_hood it will fail before the before_save gets called. Which probably explains why you got RecordNotSaved error.

要记住的另一件事是，如果您有布尔值属性，您也不能使用 validate_presence_of 。参见 http://alexanderwong.me/post/16084280769/rails-validate布尔型和数组类猴子的存在

Another thing to keep in mind is that if you have a boolean property, you also can't use validate_presence_of. See http://alexanderwong.me/post/16084280769/rails-validate-presence-of-boolean-and-arrays-mongoid

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