Patch to revert a bugfix in Rails 5.2 ( https://github.com/rails/rails/commit/a84c76573fa776e377c087930dcbdc3a07eb8603 )

0_usage.rb

DisableSettingInverse.disabled = true

child = Child.new(parent_id: 12345)
parent = Parent.new
parent.children = [child]

child.parent_id # => 12345

DisableSettingInverse.disabled = false

disable_setting_inverse.rb

module DisableSettingInverse
  class << self
    attr_accessor :disabled
  end

  def set_inverse_instance(record)
    super unless DisableSettingInverse.disabled
  end
end

ActiveRecord::Associations::CollectionAssociation.prepend DisableSettingInverse