@ActionState

Action state decorator. Temporarily enters a specified state during async execution, returns to the original state after.

Signature

function ActionState(name?: string): MethodDecorator

Parameters

Parameter	Description
name	Temporary state name. Defaults to the method name if omitted.

Behavior

class Doc extends FSM {
  @ActionState('saving')
  async save() {
    await persist()
  }
}

Running save():

1. Record old = this.state
2. setState('saving') (note: directly to 'saving', not a MiddleState)
3. Run the original method
   • Success: setState(old), return the result
   • Failure: setState(old, err), throw the original error

vs @ChangeState

	@ChangeState	@ActionState
Pre-execution validation	validates from	none
Post-execution state	new stable state to	returns to original
Intermediate	MiddleState (${action}ing)	directly name
In stateDiagram	yes	no
Failure rollback	to from	to original

Caution

@ActionState does not register in the module-level stateDiagram Map, so it doesn’t appear in the auto-generated mermaid diagram. It describes a transient action, not a formal node.

Sync method support

If the original method returns a sync value, behavior is the same (sync return, state restored):

@ActionState('refreshing')
refresh() {
  return this.cache
}

Example

The dataFetch example uses @ActionState('retrying') to surface the retry-wait intermediate state.

See also

• Guide: Other Decorators
• @ChangeState