calling custom validation methods in Rails

Question

I just upgraded my rails to 2.3.4 and I noticed this with validations: Lets say I have a simple model Company which has a name. nothing to it. I want to run my own validation:

class Company < ActiveRecord::Base

  validate :something


  def something
    false
  end

end

saving the model actually works in this case. The same thing happens if i override validate() and return false. I noticed this in a more complex model where my validation was returning false, but the object was still saving...I tried it out in an essentially empty model and the same thing applied. Is there a new practice I am missing? This doesn't seem to be the case in some of my older rails code.

Thank you. That is almost definitely the case. I assume with the new project I forgot to add errors, and with the older ones I definitely had them in there. Duh. thank you all. — cgr
– cgr, Commented Oct 23, 2009 at 7:50

Damien MATHIEU · Accepted Answer · 2013-08-21 12:38:36Z

118

Your validations are executed when you use the validate method. However rails doesn't relies on the returned value.

It relies on if there are validations errors or not. So you should add errors when your model doesn't validates.

def something
    errors.add(:field, 'error message')
end

Or, if the error is not related to a field :

def something
    errors.add(:base, 'error message')
end

Then your model won't be saved because there are errors.

edited Aug 21, 2013 at 12:38

answered Oct 23, 2009 at 7:47

Damien MATHIEU

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1 Comment

Undistraction Over a year ago

add_to_base is no longer correct as of Rails 3. See @MagedMakled's answer.

EmFi · Accepted Answer · 2009-10-23 07:56:15Z

16

You're getting confused between validations and callbacks.

Validations are supposed to fail if there are any errors on the object, doesn't matter what the validation returns. Callbacks fail if they return false, regardless if they add any errors to object.

Rails uses calls valid? from save calls which does not check the result of any validations.

Edit: Rails treats validate :method as a callback, but valid? still doesn't check for their results, only for errors they added to the object.

I don't think this behaviour changed at all but I could be wrong. I don't think I've ever written a validation to return false before.

edited Oct 23, 2009 at 7:56

answered Oct 23, 2009 at 7:47

EmFi

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1 Comment

Coderama Over a year ago

I was trying to create a validation for new_records so I created a method for use with the callback Obj.before_validation_on_create and added some base errors. However, the object would be created even when my callback added a base error. It only worked when I made my callback return "false" like you suggested! Thanks for pointing out how to make the callback fail

Maged Makled · Accepted Answer · 2013-06-08 22:14:25Z

8

Just FYI errors.add_to_base('error message') has been deprecated in rails 3 and got replaced by

errors[:base] << "Error message"

Or

errors.add(:base, "Error message")

answered Jun 8, 2013 at 22:14

Maged Makled

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