Alex Rivera | Logout

Rails: How to use before_save to change a field value based on another field?

Asked 2012-08-02T17:46:07.413
23

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

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

ActiveRecord::RecordNotSaved: ActiveRecord::RecordNotSaved

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

Update

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

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

ruby-on-rails-3 activerecord
Edit
Report

1 Answer

26

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

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.

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

answered 2012-08-02T17:53:39.723

Your Answer