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>

[Source]

     # File lib/state_machine/event_collection.rb, line 114
114:     def attribute_transition_for(object, invalidate = false)
115:       return unless machine.action
116:       
117:       result = machine.read(object, :event_transition) || if event_name = machine.read(object, :event)
118:         if event = self[event_name.to_sym, :name]
119:           event.transition_for(object) || begin
120:             # No valid transition: invalidate
121:             machine.invalidate(object, :event, :invalid_event, [[:state, machine.states.match!(object).human_name(object.class)]]) if invalidate
122:             false
123:           end
124:         else
125:           # Event is unknown: invalidate
126:           machine.invalidate(object, :event, :invalid) if invalidate
127:           false
128:         end
129:       end
130:       
131:       result
132:     end

Gets the list of transitions that can be run on the given object.

Valid requirement options:

• :from - One or more states being transitioned from. If none are specified, then this will be the object‘s current state.
• :to - One or more states being transitioned to. If none are specified, then this will match any to state.
• :on - One or more events that fire the transition. If none are specified, then this will match any event.
• :guard - Whether to guard transitions with the if/unless conditionals defined for each one. Default is true.

Examples

  class Vehicle
    state_machine :initial => :parked do
      event :park do
        transition :idling => :parked
      end

      event :ignite do
        transition :parked => :idling
      end
    end
  end

  events = Vehicle.state_machine.events

  vehicle = Vehicle.new                             # => #<Vehicle:0xb7c464b0 @state="parked">
  events.transitions_for(vehicle)                   # => [#<StateMachine::Transition attribute=:state event=:ignite from="parked" from_name=:parked to="idling" to_name=:idling>]

  vehicle.state = 'idling'
  events.transitions_for(vehicle)                   # => [#<StateMachine::Transition attribute=:state event=:park from="idling" from_name=:idling to="parked" to_name=:parked>]

  # Search for explicit transitions regardless of the current state
  events.transitions_for(vehicle, :from => :parked) # => [#<StateMachine::Transition attribute=:state event=:ignite from="parked" from_name=:parked to="idling" to_name=:idling>]

[Source]

    # File lib/state_machine/event_collection.rb, line 81
81:     def transitions_for(object, requirements = {})
82:       match(requirements).map {|event| event.transition_for(object, requirements)}.compact
83:     end

Gets the list of events that can be fired on the given object.

Valid requirement options:

• :from - One or more states being transitioned from. If none are specified, then this will be the object‘s current state.
• :to - One or more states being transitioned to. If none are specified, then this will match any to state.
• :on - One or more events that fire the transition. If none are specified, then this will match any event.
• :guard - Whether to guard transitions with the if/unless conditionals defined for each one. Default is true.

Examples

  class Vehicle
    state_machine :initial => :parked do
      event :park do
        transition :idling => :parked
      end

      event :ignite do
        transition :parked => :idling
      end
    end
  end

  events = Vehicle.state_machine(:state).events

  vehicle = Vehicle.new               # => #<Vehicle:0xb7c464b0 @state="parked">
  events.valid_for(vehicle)           # => [#<StateMachine::Event name=:ignite transitions=[:parked => :idling]>]

  vehicle.state = 'idling'
  events.valid_for(vehicle)           # => [#<StateMachine::Event name=:park transitions=[:idling => :parked]>]

[Source]

    # File lib/state_machine/event_collection.rb, line 41
41:     def valid_for(object, requirements = {})
42:       match(requirements).select {|event| event.can_fire?(object, requirements)}
43:     end