CODEWITHSUNDEEP
flutterdartbloc
user54517
user54517

Reputation: 2430

Bloc Listener : access to the previous state

There is one line of my code in my BlocListener that I would like to run only if a condition on the previous state is met. So is it possible to get access to the previous state in the listener, I know I can get access to it in the listenWhen parameter.

BlocListener<AuthenticationBloc, AuthenticationState>(
            listener: (context, state) {
              switch (state.status) {
                case AuthenticationStatus.authenticated:

                  context.read<GetOffersCubit>().getOffersInMyArea();
                  context.read<GetRequestsCubit>().getRequestsInMyArea();
                  context.read<GetFavoritesCubit>().getFavorites();
                  PushNotificationsManager instanceNotificationManager = PushNotificationsManager();
                  instanceNotificationManager.init(state.user.id);

                  // this line should run only if previous.status != AuthenticationStatus.authenticated
                  context.read<NavigatorBloc>().add(GoToMainFrameScreen());

Upvotes: 1

Views: 6525

Answers (2)

function1983
function1983

Reputation: 1186

The functionality you asked for is built in. Bloc documentation

BlocListener<BlocA, BlocAState>(
    listenWhen: (previousState, currentState) {
        //return true to invoke listener function
        return true;  
    },
    listener: (context, state) {
        // do stuff here based on BlocA's state
    },
    child: Container(),
)

Upvotes: 2

Loren.A
Loren.A

Reputation: 5595

You could add the status to a list every time it changes then access the previous status from the list.

I can't test this of course because I don't have your full code but something like this should work.

 List statusList = [];
 BlocListener<AuthenticationBloc, AuthenticationState>(
            listener: (context, state) {
              statusList.add(state.status); // adding to list before hitting switch/case
              switch (state.status) {
                case AuthenticationStatus.authenticated:

                  context.read<GetOffersCubit>().getOffersInMyArea();
                  context.read<GetRequestsCubit>().getRequestsInMyArea();
                  context.read<GetFavoritesCubit>().getFavorites();
                  PushNotificationsManager instanceNotificationManager = PushNotificationsManager();
                  instanceNotificationManager.init(state.user.id);
                
                  final previousStatusIndex = statusList.length - 1;
                  final previousStatus = statusList[previousStatusIndex];

          // this line should run only if previous.status != AuthenticationStatus.authenticated

                  if (previousStatus != AuthenticationStatus.authenticated) {
                 
                  context.read<NavigatorBloc>().add(GoToMainFrameScreen());
                    }

Upvotes: 1

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