class StateMachine::EventCollection

Represents a collection of events in a state machine

Public Instance Methods

attribute_transition_for(object, invalidate = false) click to toggle source

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>
    # File lib/state_machine/event_collection.rb
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
transitions_for(object, requirements = {}) click to toggle source

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>]
   # File lib/state_machine/event_collection.rb
81 def transitions_for(object, requirements = {})
82   match(requirements).map {|event| event.transition_for(object, requirements)}.compact
83 end
valid_for(object, requirements = {}) click to toggle source

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