this-is-not-circular-dependency-error-now.dart

import 'package:flutter_riverpod/flutter_riverpod.dart';

class Item {
  final String name;
  final int price;

  Item(this.name, this.price);
}

final inventoryProvider =
    NotifierProvider<InventoryNotifier, List<Item>>(InventoryNotifier.new);

final itemProvider =
    NotifierProvider.family<ItemNotifier, Item, int>(ItemNotifier.new);

class InventoryNotifier extends Notifier<List<Item>> {
  @override
  List<Item> build() {
    return [
      Item('Apple', 10),
      Item('Banana', 20),
      Item('Cherry', 30),
    ];
  }

  updateItem(int index, Item item) {
    final s = [...state];
    s[index] = item;
    state = s;
  }
}

class ItemNotifier extends FamilyNotifier<Item, int> {
  @override
  Item build(int arg) {
    return ref.watch(inventoryProvider)[arg];
  }

  void incrementPrice() {
    ref
        .read(inventoryProvider.notifier)
        .updateItem(arg, Item(state.name, state.price + 1));
  }
}