StatesmanScaffold

Scaffold Statesman state machines for ActiveRecord models. Generates StateMachine, Transition classes, and migrations with a single rake task, plus a with_state_machine concern that wires up delegation, query scopes, and transition associations.

• One rake task generates StateMachine class, Transition model, and migration
• with_state_machine class macro wires up Statesman with a single line
• Delegates current_state, transition_to!, transition_to, can_transition_to? to the state machine
• Adds in_state? and not_in_state? convenience predicates
• Includes Statesman::Adapters::ActiveRecordQueries for query scopes
• Supports namespaced models (e.g. Admin::Order)
• Rails installer that configures Statesman adapter and auto-includes the concern

Add to your application's Gemfile:

gem "statesman_scaffold"

Then run:

bundle install
rails statesman_scaffold:install

The installer creates config/initializers/statesman_scaffold.rb which configures Statesman to use the ActiveRecord adapter and auto-includes StatesmanScaffold::Concern into every ActiveRecord model.

rails "statesman_scaffold:generate[Project]"

This creates three files:

• app/models/project/state_machine.rb – the Statesman state machine class
• app/models/project/transition.rb – the transition model
• db/migrate/TIMESTAMP_create_project_transitions.rb – the migration

class Project < ApplicationRecord
  STATUSES = Project::StateMachine.states

  with_state_machine

  attribute :status, :string, default: Project::StateMachine.initial_state
  validates :status, inclusion: { in: STATUSES }, allow_nil: true
end

Edit the generated app/models/project/state_machine.rb:

class Project::StateMachine
  include Statesman::Machine

  state :active, initial: true
  state :pending
  state :skipped
  state :cancelled
  state :done

  transition from: :active, to: [:pending, :skipped, :cancelled, :done]
  transition from: :pending, to: [:skipped, :cancelled, :done]
  transition from: :skipped, to: [:pending]

  after_transition do |model, transition|
    model.update!(status: transition.to_state)
  end
end

project = Project.create!(name: "Demo")

project.current_state              # => "active"
project.in_state?(:active)         # => true
project.not_in_state?(:done)       # => true

project.can_transition_to?(:pending) # => true
project.transition_to!(:pending)
project.current_state              # => "pending"
project.status                     # => "pending"

# Non-bang version returns true/false instead of raising
project.transition_to(:done)       # => true

# Query scopes (via Statesman::Adapters::ActiveRecordQueries)
Project.in_state(:active)
Project.not_in_state(:cancelled)

rails "statesman_scaffold:generate[Admin::Order]"

This generates Admin::Order::StateMachine, Admin::Order::Transition, and the corresponding migration with proper table names and foreign keys.

rails statesman_scaffold:install    # create config/initializers/statesman_scaffold.rb
rails statesman_scaffold:uninstall  # remove config/initializers/statesman_scaffold.rb
rails "statesman_scaffold:generate[ModelName]"  # generate state machine files

class Project < ApplicationRecord
  include StatesmanScaffold::Concern
  with_state_machine
end

bin/setup         # install dependencies
bundle exec rake  # run tests
bin/console       # interactive prompt

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

MIT -- see LICENSE.txt.