ActiveRecord::Fsm

A simple Finite State Machine.
Use this gem to auto define Finite State Machine on ActiveRecord with one column named status.

The goal of this gem is to monitor record with wrong state, and then help us to stats whether or not the code works well.
The next step is to add monitor to FSM, and now it is currently UNDER DEVELOPMENT.

Installation

Add this line to your application's Gemfile:

gem 'activerecord-fsm'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install activerecord-fsm

Maybe you need to do migration, add one column named status:

bin/rails generate migration AddStatusToFsmModel status:integer:index  
# or you can specify column type
bin/rails generate migration AddStatusToFsmModel status:{column_type}:index

Usage

1. Include ActiveRecord::Fsm into ApplicationRecord/ActiveRecord::Base or directly into FsmModel.

2. Use #fsm_define to arrange permit_transitions set in which status can be transitioned from one to another. This will add:

    validates :status, presence: true, inclusion: { in: self.fsm_graph.states }
    validate :fsm_graph_check_permit_transitions, on: :update, if: :will_save_change_to_status?
   

   fsm_graph_check_permit_transitions has been defined as:

     def fsm_graph_check_permit_transitions
       unless self.class.fsm_graph.valid_transition?(*self.status_change)
         self.errors.add(:status, 'no permit status change')
         throw :abort
       end
     end
   

   Model without using fsm_define will only act as the same with NormalModel which doesn't has fsm mechanic.
   In other words, using fsm_define will make NormalModel become FsmModel.

3. Use FsmModel.fsm_graph.transitions to get all permit_transition you defined.

4. Use FsmModel.fsm_graph.states to get all permit_status you defined.

5. Use FsmModel.fsm_graph.final_states.include?(fsm_instance.status) to judge FsmModel instance fsm_instance terminate?.

6. Use ActiveRecord::Fsm::Graph.defined_klasses to get all the models which really used ActiveRecord::Fsm.

e.g.

class ApplicationRecord < ActiveRecord::Base
  include ActiveRecord::Fsm

  self.abstract_class = true
  # blablabla......
end

# FsmModel need call fsm_define
class FsmModel < ApplicationRecord
  STATE_1 = 1
  STATE_2 = 2
  STATE_3 = 3

  PERMIT_TRANSITIONS = [
    [STATE_1, STATE_2],
    [STATE_2, STATE_3],
    [STATE_1, STATE_3],
  ]

  fsm_define(PERMIT_TRANSITIONS, fsm_column = "status")
end

# FsmModel can be shown having used ActiveRecord::Fsm
ActiveRecord::Fsm::Graph.defined_klasses
# => [FsmModel]

# NormalModel doesn't call fsm_define
# although inherited from ApplicationRecord
class NormalModel < ApplicationRecord
end

# NormalModel is not included
ActiveRecord::Fsm::Graph.defined_klasses
# => [FsmModel]

UpdateLog

v 0.1.4

add instance_variable mid_states and instance_method mid_state?(state) for ActiveRecord::Fsm::Graph

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/ElliotCui/activerecord-fsm.

License

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