Spring State Machine - Attaching static data to states

Question

With spring state machine, we have states and events. I could not find any documentation on whether it is possible to attach static data to a state during configuration.

Answer 1

This is achieved with two objects in the state machine - StateContext and ExtendedState.

StateContext is like a current snapshot of the State Machine - it's passed around in various methods and callbacks, including actions and guards.

ExtendedState is basically a map with variables.

You can get the ExtendedState from the StateContext:

    context.getExtendedState()
        .getVariables().put("mykey", "myvalue");

As it is passed around as part of the context, you can access the ExtendedState in every action, transition, guard etc. The StateMachine object itself also has a getExtendedState() method.

This is the canonical way to pass static data around in the StateMachine.