EnumTransitions

Rails provides ActiveRecord::Enum which is great for state machines. The only problem is that it doesn't provide built-in validations for transitions.

Add this line to your application's Gemfile:

gem 'enum_transitions'

And then execute:

$ bundle

Or install it yourself as:

$ gem install enum_transitions

For example, let's say you have a Car model:

class Car < ApplicationRecord
  enum state: [ :parked, :drive, :reverse ]

  enum_transitions state: {
    parked: [ :drive, :reverse ],
    drive: :parked,
    reverse: :parked
  }
end

Then when you call the transition methods (provided by ActiveRecord::Enum), an error will raise if the transition is invalid:

car = Car.create!
car.drive! #=> car.state == :drive
car.reverse! #=> raises EnumTransitions::InvalidTransition

car.transitions_to_reverse? #=> false
car.transitions_to_parked? #=> true

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 tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/listia/enum_transitions.