state_machine

StateMachine::EventCollection#attribute_transition_for

Gets the transition that should be performed for the event stored in the
given object's event attribute.  This also takes an additional parameter
for automatically invalidating the object if the event or transition are
invalid.  By default, this is turned off.

*Note* that if a transition has already been generated for the event, then
that transition will be used.

== Examples

  class Vehicle < ActiveRecord::Base
    state_machine :initial => :parked do
      event :ignite do
        transition :parked => :idling
      end
    end
  end
  
  vehicle = Vehicle.new                       # => #<Vehicle id: nil, state: "parked">
  events = Vehicle.state_machine.events
  
  vehicle.state_event = nil
  events.attribute_transition_for(vehicle)    # => nil # Event isn't defined
  
  vehicle.state_event = 'invalid'
  events.attribute_transition_for(vehicle)    # => false # Event is invalid
  
  vehicle.state_event = 'ignite'
  events.attribute_transition_for(vehicle)    # => #<StateMachine::Transition attribute=:state event=:ignite from="parked" from_name=:parked to="idling" to_name=:idling>

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