NullAssociations

Return null objects for your Rails belongs_to and has_one associations.

Add this line to your application's Gemfile:

gem 'null_associations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install null_associations

Supply a new option with your has_one or belongs_to declarations.

class NullDuck
  def quack
    ''
  end
end

class Duck < ApplicationRecord
  def quack
    'quack! quack!'
  end
end

class Duckling < ApplicationRecord
  belongs_to :duck, null_object: NullDuck
end

duck = Duckling.create!(duck: nil)
duckling.duck.quack
=> ""

These can become even more powerful with ActiveRecord::QueryMethods.none.

class NullDuck
  def ducklings
    Duck.none
  end

  def quack
    ''
  end
end

class Duck < ApplicationRecord
  has_many :ducklings

  def quack
    'quack! quack!'
  end
end

class Duckling < ApplicationRecord
  scope :brown, -> { where(brown: true) }
  belongs_to :duck, null_object: NullDuck
end

duck = Duckling.create!(duck: nil)
duckling.duck.ducklings.brown.where('created_at > ?', 2.days.ago)
=> []

After checking out the repo, run bin/setup to install dependencies. Then, run rake test 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 tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/wohlgejm/null_associations. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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

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