ohm-stateful-model

Integrate state machines (from the state_machine gem) into your Ohm models.

Setup

Require the gem:

require 'ohm/stateful_model'

Define your state machine and inherit from Ohm::State:

class VehicleState < Ohm::State
  state_machine :state, :initial => :parked do
    event :park do
      transition :idling => :parked
    end
  
    event :start_car do
      transition :parked => :idling
    end
  end
end

Define your Ohm model by inheriting from Ohm::StatefulModel. Specify the state machine to use via the use_state_machine class method.

class Vehicle < Ohm::StatefulModel
  use_state_machine VehicleState
end

You can specify an optional :attribute_name flag to be used as the state's model attribute. By default, the name of the state machine is used:

class Vehicle < Ohm::StatefulModel
  use_state_machine VehicleState, :attribute_name => :my_state
end

Usage

Once your state machine has been integrated into your model, you will be able to interact with it as if it were a model attribute. You will also be able to transition between states, persist the current state along with the rest of the model, and call any StateMachine::Machine methods:

v = Vehicle.new
v.state             # => "parked"

v.can_start_car?    # => true
v.start_car
v.state             # => "idling"
v.idling?           # => true
v.can_start_car?    # => false

v.new?              # => true
v.save
v.new?              # => false

# fetch persisted data
v2 = Vehicle[v.id]
v2.state            # => "idling"
v2.idling?          # => true

v2.can_park?        # => true
v2.park
v2.parked?          # => true
v2.save

Requirements

ohm-stateful-model depends on the ohm gem, which requires a running redis instance.

Running Tests

bundle exec rspec

Authors

• Cameron C. Dutro: http://github.com/camertron

Links

• state_machine gem: https://github.com/pluginaweek/state_machine
• ohm gem: https://github.com/soveran/ohm

License

Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0