Runs one or more transitions in parallel. All transitions will run through the following steps:

1. Before callbacks
2. Persist state
3. Invoke action
4. After callbacks (if configured)
5. Rollback (if action is unsuccessful)

Configuration options:

• :action - Whether to run the action configured for each transition
• :after - Whether to run after callbacks

If a block is passed to this method, that block will be called instead of invoking each transition‘s action.

Runs one or more transitions within a transaction. See StateMachine::Transition.perform for more information.

The action that will be run when this transition is performed

Runs the machine‘s after callbacks for this transition. Only callbacks that are configured to match the event, from state, and to state will be invoked.

The result can be used to indicate whether the associated machine action was executed successfully.

Once the callbacks are run, they cannot be run again until this transition is reset.

Halting

If any callback throws a :halt exception, it will be caught and the callback chain will be automatically stopped. However, this exception will not bubble up to the caller since after callbacks should never halt the execution of a perform.

Example

  class Vehicle
    state_machine do
      after_transition :on => :ignite, :do => lambda {|vehicle| ...}

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

  vehicle = Vehicle.new
  transition = StateMachine::Transition.new(vehicle, Vehicle.state_machine, :ignite, :parked, :idling)
  transition.after(true)

The attribute which this transition‘s machine is defined for

A hash of all the core attributes defined for this transition with their names as keys and values of the attributes as values.

Example

  machine = StateMachine.new(Vehicle)
  transition = StateMachine::Transition.new(Vehicle.new, machine, :ignite, :parked, :idling)
  transition.attributes   # => {:object => #<Vehicle:0xb7d60ea4>, :attribute => :state, :event => :ignite, :from => 'parked', :to => 'idling'}

Runs the machine‘s before callbacks for this transition. Only callbacks that are configured to match the event, from state, and to state will be invoked.

Once the callbacks are run, they cannot be run again until this transition is reset.

Example

  class Vehicle
    state_machine do
      before_transition :on => :ignite, :do => lambda {|vehicle| ...}
    end
  end

  vehicle = Vehicle.new
  transition = StateMachine::Transition.new(vehicle, machine, :ignite, :parked, :idling)
  transition.before

Generates a nicely formatted description of this transitions‘s contents.

For example,

  transition = StateMachine::Transition.new(object, machine, :ignite, :parked, :idling)
  transition   # => #<StateMachine::Transition attribute=:state event=:ignite from="parked" from_name=:parked to="idling" to_name=:idling>

Does this transition represent a loopback (i.e. the from and to state are the same)

Example

  machine = StateMachine.new(Vehicle)
  StateMachine::Transition.new(Vehicle.new, machine, :park, :parked, :parked).loopback?   # => true
  StateMachine::Transition.new(Vehicle.new, machine, :park, :idling, :parked).loopback?   # => false

Runs the actual transition and any before/after callbacks associated with the transition. The action associated with the transition/machine can be skipped by passing in false.

Examples

  class Vehicle
    state_machine :action => :save do
      ...
    end
  end

  vehicle = Vehicle.new
  transition = StateMachine::Transition.new(vehicle, machine, :ignite, :parked, :idling)
  transition.perform          # => Runs the +save+ action after setting the state attribute
  transition.perform(false)   # => Only sets the state attribute

Transitions the current value of the state to that specified by the transition. Once the state is persisted, it cannot be persisted again until this transition is reset.

Example

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

  vehicle = Vehicle.new
  transition = StateMachine::Transition.new(vehicle, Vehicle.state_machine, :ignite, :parked, :idling)
  transition.persist

  vehicle.state   # => 'idling'

Resets any tracking of which callbacks have already been run and whether the state has already been persisted

Rolls back changes made to the object‘s state via this transition. This will revert the state back to the from value.

Example

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

  vehicle = Vehicle.new     # => #<Vehicle:0xb7b7f568 @state="parked">
  transition = StateMachine::Transition.new(vehicle, Vehicle.state_machine, :ignite, :parked, :idling)

  # Persist the new state
  vehicle.state             # => "parked"
  transition.persist
  vehicle.state             # => "idling"

  # Roll back to the original state
  transition.rollback
  vehicle.state             # => "parked"

Runs a block within a transaction for the object being transitioned. By default, transactions are a no-op unless otherwise defined by the machine‘s integration.

Runs the callbacks of the given type for this transition. This will only invoke callbacks that exactly match the event, from state, and to state that describe this transition.

Additional callback parameters can be specified. By default, this transition is also passed into callbacks.

Gets a hash of the context defining this unique transition (including event, from state, and to state).

Example

  machine = StateMachine.new(Vehicle)
  transition = StateMachine::Transition.new(Vehicle.new, machine, :ignite, :parked, :idling)
  transition.context    # => {:on => :ignite, :from => :parked, :to => :idling}