attributes_before_type_cast is not working with accepts_nested_attributes_for and has_many association

[mateusnava]

Steps to reproduce

class User < ApplicationRecord
  has_many :schools

  accepts_nested_attributes_for :schools
end

class School < ApplicationRecord
  belongs_to :user
end

• Create a User with a School:

User.create!(name: "user 1")
User.first.schools.create!

• Assigns an attribute with the wrong format (degree_issued_at in my example):

user.assign_attributes(school_attributes: [{id: 1, degree_issued_at: "2020-30-30"}]

Expected behavior

I expected to see degree_issue_at: "2020-30-30" in the attributes_before_type_cast

Actual behavior

> user.schools.first.attributes_before_type_cast
=> {"user_id"=>1, "id"=>1, "name"=>nil, "degree_issued_at"=>nil}

System configuration

Rails version: 7.0.5

Ruby version: 3.0.1

Possible fix

Change the method ActiveModel::Type::Value#changed? to:

  def changed?(old_value, new_value, new_value_before_type_cast)
    return true if old_value.nil? && new_value.nil? && new_value_before_type_cast.present?
    ...
  end

I only could reproduce this issue with has_many, accepts_nested_attributes_for, and a persisted record with nil in the attribute.

[rails-bot]

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