onTransition method Null safety

  1. @protected
  2. @mustCallSuper
void onTransition(
  1. Transition<SubjectListEvent, SubjectListState> transition
)
@mustCallSuper, @protected, inherited

Called whenever a transition occurs with the given transition. A transition occurs when a new event is added and a new state is emitted from a corresponding EventHandler. executed. onTransition is called before a Bloc's state has been updated. A great spot to add logging/analytics at the individual Bloc level.

Note: super.onTransition should always be called first.

@override
void onTransition(Transition<Event, State> transition) {
  // Always call super.onTransition with the current transition
  super.onTransition(transition);

  // Custom onTransition logic goes here
}

See also:

  • BlocObserver.onTransition for observing transitions globally.

Implementation

@protected
@mustCallSuper
void onTransition(Transition<Event, State> transition) {
  // ignore: invalid_use_of_protected_member
  _blocObserver?.onTransition(this, transition);
}