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validates_associated throws 'can't modify frozen object' error

#5646

Steps to reproduce:
Create a value object using composed_of like in the Rails documentation. Use the :converter option to recreate the value object from the params hash when attributes= is called on the parent. Add validations to the value object. * Run those validations by using validates_associated in the entity where you have composed_of.

What happens:
* A 'can't modify frozen object' error is thrown.

Why it happens:
* Not really sure, but I tracked it as far as the valid? method in ActiveRecord::Validations. It appears to break in the "ensure" part of the that method. This was added in commit 82485068f8b64a49cbb6. When I overrode valid? in my value object, using the logic as it was before that commit, validates_associated started working as expected.

Reported by Jamie · September 17th, 2010 @ 05:35 AM

State: new
Milestone: none
Assigned to: nobody
Importance: none

Activity

  1. Bob Lail
    Bob Lail

    I dug into this a little more and wrote a blog post about the problem: Using validates_associated with composed_of and ActiveModel::Validations.

    In a nutshell:

    • ActiveRecord::Aggregations (deliberately) freezes objects assigned to a composed attribute
    • But ActiveModel::Validations tries to create two ivars: @errors and @validation_context on the frozen object

    December 30th, 2010 @ 04:11 PM

  2. bingbing
    bingbing

    March 26th, 2011 @ 01:58 AM