Is there a way to update the value of state provider in river pod after declaring it

Question

final itemCountProvider = StateProvider<int>((ref) {
  return 0;
});

i need to keep track of number of items selected in my project initially the item count would be zero but later on i need to give it the calculated value how to update the value in itemCountProvider as it is already declared final

Rimskykorsakov

If you check the riverpod in pub.dev, they have given an example for Counter app which is what you are looking for. You can follow that approach. – Awad

Answer 1

You can update the value of state provider like so:

ref.read(itemCountProvider.state).state = 10;

Here is an example counter app:

final itemCountProvider = StateProvider((ref) => 0);
class HomePage extends ConsumerWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final counter = ref.watch(itemCountProvider);
    return Scaffold(
      body: Center(
        child: Text(
          counter.toString(),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          ref.read(counterProvider.state).state += 1;
        },
      ),
    );
  }
}

Stole

.state from (itemCountProvider.state) is now deprecated use (itemCountProvider.notifier) – Patroon

Answer 2

You can update the state with read

1. If you want to update a new value every time

ref.read(itemCountProvider.state).state = newValue;

2. If you want to update based previous state value

ref.read(itemCountProvider.state).state = ref.read(itemCountProvider.state).state + newValue;

or

ref.read(itemCountProvider.state).state += newValue;

or

ref.read(counterProvider.notifier).update((state) => state + newValue);

Clamp