TransitionsListener

This gem was inspired by State Machine to listen all state transitions and make actions before and after the transition is saved.

Installation

Add this line to your application's Gemfile:

gem 'transitions_listener'

And then execute: bundle install

Usage

# == Schema Information
#
# Table name: articles
#
#  id              :bigint
#  state           :string
  
class Article < ActiveRecord::Base
  include TransitionsListener
  listen_transitions :state do
    after_transition from: :active, to: :inactive do |article, transition|
      # article.send_inactive_email
    end
    before_transition from: any, to: :deleted do |article, transition|
      # article.errors.add(:base, "not possible") if article.active_carts.any?
    end
    
    before_transition({ from: any, to: any }, if: :valid_article?, unless: :destroyed?, callback: :any_to_any_callback)
  end
  
  def any_to_any_callback
    puts "any to any callback called"
  end
  
  def valid_article?
    true
  end
  
  def destroyed?
    false
  end
end

API

• listen_transitions(attr_name){block}
  permit to define state transitions listener for a specific model attribute

• Before update
  before_transition(states, if: :action?, unless: :action?, callback: :action) { block }
  Permit to listen transitions before the new state is saved

  • states: (Mandatory) State Transition(s) to listen for
  • if: (Optional) Positive conditional action(s) to execute callback. Sample: if: :deleted? | if: [:deleted?, :ready?]
  • unless: (Optional) Negative conditional action(s) to execute callback. Sample: unless: :deleted? | unless: [:deleted?, :ready?]
  • callback: (Optional) Model method to be called as a callback (Will be overridden If block is defined)

• After update (Args are similar to before update)
  after_transition(states, if: :action?, unless: :action?, callback: :action){ block }
  permit to listen transitions after the new state was saved

States can be defined as the following:

• before_transition(from: any, to: any){} block will be called when attr value is changed from any value to any value
• before_transition(from: any, to: :active){} block will be called when attr value is changed from any value to :active
• before_transition(from: :active, to: any){} block will be called when attr value is changed from :active value to any value
• before_transition(from: %i[active inactive], to: %i[deleted cancelled]){} block will be called when attr value is changed from :active or inactive to :deleted or :cancelled
• before_transition([{ from: :active, to: :inactive }, { from: :inactive: :deleted }]){} block will be called when attr value is changed from :active to :inactive or :inactive to :deleted
• before_transition([{ active: :inactive, inactive: :deleted }]){} block will be called when attr value is changed from :active to :inactive or :inactive to :deleted (Shorter state definitions. Same as above)

Development

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.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/transitions_listener. 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.

License

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

Code of Conduct

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