Build status for all matrix combinations listed in compatibility



class Harbor
  has_many :ships

  accepts_nested_attributes_for :ships, allow_destroy: true

harbor.ships_attributes = [harbor.ships.first.attributes.merge('_destroy': true)]!

harbor.ships_destroyed_during_save? # true

See that last line of code? That is what this gem adds :smiley:


Active Record offers introspection of saved changes for almost everything you could want. The one thing I have repeatedly found myself wishing for was a way to know if a nested attribute was destroyed during save via accepts_nested_attributes.

The only way I know to find that information is to set a flag in a callback before saving, then use that flag for state comparison after the save completes.

This gem handles setting the flags before saving and adds introspection into the state after the save.


Add this line to your application's Gemfile:

gem 'activerecord-nested_attribute_destruction'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install activerecord-nested_attribute_destruction



When you call #accepts_nested_attributes_for, this gem will automatically install its hooks on the class. One method is also added to the class instance API: <association_name>_destroyed_during_save?.

For example:

has_many :ships
has_one  :accountant

accepts_nested_attributes_for :ships, :accountant, allow_destroy: true

You can call ships_destroyed_during_save? and accountant_destroyed_during_save? after a save to check if associated ships or the accountant were destroyed through nested attribute assignment during the save.


Here is an example of how it works, adapted from the test suite.

def print_result(h)
  if h.ships_destroyed_during_save?
    puts "At least one ship was destroyed during the last save operation"
    puts "No ships were destroyed during the last save operation"

harbor = DangerousHarbor.create(name: 'Blue Lagoon')
ship1 = (harbor.ships << Ship.create(harbor: harbor)).first
ship2 = (harbor.ships << Ship.create(harbor: harbor)).first

harbor.ships_attributes = [
  ship1.attributes.merge('_destroy': true),
  ship2.attributes.merge(fuel_remaining: 10)

and the output when the code above is run:

At least one ship was destroyed during the last save operation
No ships were destroyed during the last save operation

To see more examples, take a look at the tests.


This gem should be compatible with all versions of Ruby 2.3 and higher. It should be compatible with Active Record versions 5.2 and up.

Because of rubocop dependencies and keyword arguments changes in Ruby 3.0 which affected the database setup code used in the test suite, it is only tested against the matrices displayed below.

Sorted by Active Record version

Active Record version Ruby Version
5.2 2.5
5.2 2.6
5.2 2.7
6.0 2.5
6.0 2.6
6.0 2.7
6.1 2.5
6.1 2.6
6.1 2.7
6.1 3.0
7.0 2.7
7.0 3.0

Sorted by Ruby version

Ruby Version Active Record version
2.5 5.2
2.5 6.0
2.5 6.1
2.6 5.2
2.6 6.0
2.6 6.1
2.7 5.2
2.7 6.0
2.7 6.1
2.7 7.0
3.0 6.1
3.0 7.0

Specific requirements


The safe navigation operator, introduced in Ruby 2.3, is used.

Active Record

The API changes in Active Record 5.2 are necessary for the core functionality of the gem.


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at\_attribute\_destruction. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.