ActiveRecord 2.3: Nested attribute changes disappear

There is a bug in ActiveRecord 2.3.x that leads to changes in nested forms getting lost.

class Project < ActiveRecord::Base
  has_many :tasks
  accepts_nested_attributes_for :tasks
end

If you access project.tasks after setting tasks through the nested attribute logic, all tasks will be reloaded and all changes will be lost. This usually happens

• in validations
• in callbacks
• after validation errors, when rendering the view again

The attached initializer fixes those issues.