StateMachine::EventCollection

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, line 114
def attribute_transition_for(object, invalidate = false)
  return unless machine.action
  
  result = machine.read(object, :event_transition) || if event_name = machine.read(object, :event)
    if event = self[event_name.to_sym, :name]
      event.transition_for(object) || begin
        # No valid transition: invalidate
        machine.invalidate(object, :event, :invalid_event, [[:state, machine.states.match!(object).human_name(object.class)]]) if invalidate
        false
      end
    else
      # Event is unknown: invalidate
      machine.invalidate(object, :event, :invalid) if invalidate
      false
    end
  end
  
  result
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>]

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

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