Cubit not rebuilding when emiting a new state - flutter

Question

Whenever I call the toggleLocked event, the BlocBuilder does not rebuild the widget.
I have looked around a lot on the internet and found this explanation: https://stackoverflow.com/a/60869187/3290471
I think that somewhere I incorrectly use the equatable package which results in the fact that the BlocBuilder thinks nothing has changed (while is has).
I have read the FAQ from the Bloc libray and the three provided solution (props for equatable / not reusing the same state / using fromList) seem to not fix the problem.
My Cubit:
class LockCubit extends Cubit<LockState> {
LockCubit({#required this.repository})
: assert(repository != null),
super(LockInitial());
final LocksRepository repository;
Future<void> fetch() async {
try {
final locks = await repository.fetchLocks();
emit(LocksDisplayed().copyWith(locks));
} on Exception {
emit(LockError());
}
}
Future<void> toggleLocked(int id) async {
try {
final locks = await repository.toggleLocked(id);
emit(LocksDisplayed().copyWith(List.from(locks)));
} on Exception {
emit(LockError());
}
}
}
My states:
abstract class LockState extends Equatable {
const LockState();
#override
List<Object> get props => [];
}
class LockInitial extends LockState {
#override
String toString() => 'LocksUninitialized';
}
class LockError extends LockState {
#override
String toString() => 'LockError';
}
class LocksDisplayed extends LockState {
final List<Lock> locks;
const LocksDisplayed([this.locks = const []]);
LocksDisplayed copyWith(locks) => LocksDisplayed(locks ?? this.locks);
#override
List<Object> get props => [locks];
#override
String toString() => 'LocksDisplayed { locks: $locks }';
}
My model:
class Lock extends Equatable {
Lock({this.id, this.name, this.locked, this.displayed});
final int id;
final String name;
final bool locked;
final bool displayed;
#override
String toString() =>
'Lock { id: $id name: $name locked: $locked displayed: $displayed }';
Lock copyWith({id, name, locked, displayed}) => Lock(
id: id ?? this.id,
name: name ?? this.name,
locked: locked ?? this.locked,
displayed: displayed ?? this.displayed);
#override
List<Object> get props => [id, name, locked, displayed];
}
My repositotory:
class LocksRepository {
List<Lock> locks = [];
Future<List<Lock>> fetchLocks() async {
// This is a temporary implementation
// In the future the data should be fetched from a provider
locks = [
new Lock(
id: 0,
name: 'Voordeur',
locked: false,
),
new Lock(
id: 1,
name: 'Achterdeur',
locked: false,
)
];
return locks;
}
Future<List<Lock>> toggleLocked(int id) async {
// This is a temporary implementation
// In the future a request to change a lock should be made and then the specific lock should be retrieved back and edited.
locks[id] = locks[id].copyWith(locked: !locks[id].locked);
return locks;
}
}
I am changing a state with the following trigger:
context.read<LockCubit>().toggleLocked(focusedIndex);
I am using BlocBuilder like this to build the state:
BlocBuilder<LockCubit, LockState>(builder: (context, state) {
print('State Changed');
if (state is LockInitial) {
return Text('lockInitial');
}
if (state is LocksDisplayed) {
return Swiper(
itemBuilder: (BuildContext context, int index) {
return Column(
children: [
Text(state.locks[index].name),
Text(state.locks[index].locked.toString())
],
);
},
onIndexChanged: onIndexChanged,
loop: true,
itemCount: state.locks.length);
}
if (state is LockError) {
return Text('lockError');
}
return Container();
});
All help would be very appreciated.

Answer 1

Can you check BlocProvider ? I got the same problem. If this bloc inside materialApp, you must pass BlocProvider.value not create in widget.

Answer 2

I am a bit confused, if this could work. But with a bloc you would use an event not a cubit (even though events are based on cubits).
So first of all I would use the standard pattern:
state
event
bloc with mapEventToState
Then, what I also do not see in your code, if you toggle your lock it would look like this in pseudo code
if (event is toggleLock) {
yield lockInProgress();
toggleLock();
yield locksDisplayed;
}
This way your state always changes from locksDisplayed to lockInProgress to locksDisplayed - just as you read in your link above