enum_state_machine
==================
state_machine patches to use PowerEnum enums for state values.
It allows you to use an enumerated attribute to track a state machine status.
Installation:
Add the following to your Gemfile:
gem 'enum_state_machine'Usage:
Before using this you must familiarize yourself with the PowerEnum and state_machine gems.
Include EnumStateMachine::StateEnum in our model. That adds a single method that is used to define an enumerated state attribute:
# state_attr is the name of the state variable
# enum_attr is the name of the underlying enumerated attribute
# enum_opts are options to be passed to has_enumerated
has_state_enum(state_attr, enum_attr, enum_opts = {})This is best illustrated with an example. Suppose you have a Grenade model that can have four possible states: stored, armed, kaboom, and fizzle.
# Migration
create_enum :grenade_status
create_table :grenades do |t|
t.references :grenade_statuses
t.boolean :is_defective
t.timestamps
end
# Seeds
GrenadeStatus.update_enumerations_model do
[:unarmed, :armed, :kaboom, :fizzle].each { |name| GrenadeStatus.create! name: name }
end
# Models
class GrenadeStatus < ActiveRecord::Base
acts_as_enumerated
end
class Grenade < ActiveRecord::Base
include EnumStateMachine::StateEnum
has_state_enum :status, :grenade_status, default: :unarmed
state_machine :status, initial: :unarmed do
event :pulled_pin do
transition :unarmed => :armed
end
event :thrown do
# a defective grenade won't explode
transition :armed => :fizzle, :if => :is_defective?
# a normal armed one will explode
transition :armed => :kaboom
# If you forgot to pull the pin, nothing happens
transition :unarmed => :unarmed
end
end
end