Cancelable Feature

sample_cancalable.dart

class SamplePage extends StatefulWidget {
  const SamplePage({Key? key}) : super(key: key);

  @override
  _SamplePageState createState() => _SamplePageState();
}

class _SamplePageState extends State<SamplePage> {
  void _fetchItems() {
    _operation.value.then((value) {
      _items = value ?? [];
      setState(() {});
    });
  }

  late CancelableOperation<List<UserModel>?> _operation;
  List<UserModel> _items = [];
  @override
  void initState() {
    super.initState();
    _operation = CancelableOperation.fromFuture(
      SampleFutureCancel().fetchUsers(),
      onCancel: () {
        print('The request has been Canceled');
      },
    );

    _fetchItems();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(leading: Text('${_items.length}')),
      floatingActionButton: FloatingActionButton(
        child: Text('Cancel Request'),
        onPressed: () {
          _operation.cancel();
        },
      ),
    );
  }
}