使用accept_nested_attributes_for进行验证

Question

I'm having issues with some code of my rails app, imagine the follow scenario:

user.rb

class User < ActiveRecord::Base  
  has_one :participant, dependent: :destroy
  validates_presence_of :username

  accepts_nested_attributes_for :participant
end

participant.rb

class Participant < ActiveRecord::Base  
  belongs_to :user
  validates_presence_of :phone_number
end

The problem happens when I run valid? method

user = User.first
user.valid?
#=> true

At this point user validations are ok (it's running only the validations from User model), but if for some reason the association with participant is loaded, then valid? method's gonna run the validations from User and from Participant which IMHO is wrong since user is an instance of User model

user.participant  
Participant Load (0.3ms)  SELECT "participants".* FROM "participants" WHERE "participants"."user_id" = ? LIMIT 1  [["user_id", 1]]  
 => #<Participant id: 1, user_id: 1, phone_number: "", created_at: "2015-01-13 18:15:34", updated_at: "2015-01-13 18:48:27">
user.valid?  
#=>false
user.errors.full_messages  
#=> ["Participant phone number can't be blank"]

I would agree with this validation if I were updating something in participant model but I'm not. Is this a bug or there is any way that I could skip the associated validations?

Thanks

Answer 1

In Rails nested attributes pass behavior to the parents children. So if you call .valid? on the parent it will check validations on all the children . This is the intended structure and is this way to ensure that the associated model is valid, because you asked it to be.

The question I have for you is why would you have a validation on your Participant model for the phone_number attribute if you want to skip that validation? You either need to remove the validation for phone_number or ensure that a phone_number is present. I think you need to re-assess the structure of your model's and validations with this in mind.