What would cause a Flutter Redux StoreConnector to not rebuild.

[Joematpal]

I try to follow the issues religiously on the flutter_architecture_sample. Thank you, to all of you that contribute and ask questions. It helps a lot. I have not seen an issue like this and I could not find the right search query to bring up anything close to my problem. I would really appreciate some help if anyone has an idea as to why this StoreBuilder is not rebuilding. The underlying state of the reducer is two Map<String, Whatevers>'s. I tried to add code without overwhelming the post.

    #View
    return ListView.builder(
                itemCount: eventIDs.length,
                itemBuilder: (BuildContext context, int i) {
                  return StoreConnector<AppState, EventsPageViewModel>(
                      rebuildOnChange: true,
                      onDidChange: (EventsPageViewModel events) {print('${events}');},
                      onInit: (store) =>
                          store.dispatch(FetchEventAction(id: eventIDs[i])),
                      converter: (store) => EventsPageViewModel.fromStore(store),
                      builder: (BuildContext context, EventsPageViewModel events) {
                        print("build ListItem $i ${eventIDs[i]}");
                        if (events.events.containsKey('${eventIDs[i]}')) {
                          return EventCard(
                            event: events.events[eventIDs[i]],
                          );
                        }
                        return Container(
                          child: Card(
                            child: Container(
                              height: 120.0,
                            ),
                          ),
                        );
                      });
                },
              );
    #State
    @immutable
    class Events {
      Events({
        this.loadingStatus,
        this.events,
      });

      factory Events.initial() {
        return Events(
          loadingStatus: Map<String, LoadingStatus>(),
          events: Map<String, EventModel>(),
        );
      }

      final Map<String, LoadingStatus> loadingStatus;
      final Map<String, EventModel> events;

      Events copyWith({
        Map<String, LoadingStatus> loadingStatus,
        Map<String, EventModel> events,
      }) {
        return Events(
          loadingStatus: loadingStatus ?? this.loadingStatus,
          events: events ?? this.events,
        );
      }

      @override
      bool operator ==(Object other) =>
          identical(this, other) ||
          other is Events &&
              runtimeType == other.runtimeType &&
              loadingStatus == other.loadingStatus &&
              const MapEquality().equals(events, other.events);

     @override
     int get hashCode => loadingStatus.hashCode ^ const MapEquality().hash(events);
    }


    #ViewModel
    class EventsPageViewModel {
      EventsPageViewModel({
       @required this.status,
       @required this.events,
     });

     final Map<String, LoadingStatus> status;
     final Map<String, EventModel> events;

     static EventsPageViewModel fromStore(
       Store<AppState> store,
     ) {
       return EventsPageViewModel(
         status: store.state.events.loadingStatus,
         events: store.state.events.events,
       );
     }

     @override
     bool operator ==(Object other) =>
         identical(this, other) ||
         other is EventsPageViewModel &&
             runtimeType == other.runtimeType &&
             status == other.status &&
             const MapEquality().equals(events, other.events);

     @override
     int get hashCode => status.hashCode ^ const MapEquality().hash(events);
    }

I'm trying to get a view to rebuild after it fire off an async action and it return a value to a Map. I don't know if i'm doing the equality check properly

I checked to see if the middleware was firing off the GET Request. It is. I checked to see if the GET request was returning information. It is. I have another async action that is firing. That one returns a List of string and does trigger a rebuild on its StoreConnector.

Does anyone have any clues as to why the StoreConnector does not detect a diff?

[brianegan]

Hey there -- hrm, this is a funny one. I can't quite spot anything suspicious in the code that you've pasted, it looks pretty "standard" to me. Do you happen to have a full project you can share, or perhaps sharing some of the Middleware / Reducer code as well?

[Joematpal]

https://github.com/Joematpal/trial-flutter-app

Thank you for looking at this.

[mmcc007]

@Joematpal The link above is no longer working. Were you able to resolve this? If so please close this issue. Otherwise feel free to add to this issue.

[akdu12]

@Joematpal I have the same issue as yours, Were you able to resolve the problem?

[DFreds]

I could be wrong, but I believe this is because Maps (as well as Lists) need to return a new Map (or List) on update from the reducer. You cannot update the old map because the Redux package will not understand that it needs to rebuild. I assume this is due to the internals of the built in Map and List objects being unable to accurately create a hashCode/equals due to the generics, but I'm not 100% sure.