flutter - 如何使用 flutter riverpod statenotifier、ref watch 和 asyncvalue 获取加载状态/微调器？

Question

我有下面的示例，它确实刷新了数据，但没有按预期提供微调器。我尝试使用 ref.listen 切换到异步加载，我尝试在调用前等待，即使它没有意义。

我尝试了 ref.refresh、ref.invalidate...预期行为:打开应用，查看微调器，点击按钮，在文本更改之前再次查看微调器。实际行为:打开应用，看到微调器，点击按钮，文本发生变化，但没有微调器显示。另见 https://github.com/neiljaywarner/riverpod_watching_dep_no_spinner_sample我正在使用 flutter 3.0.5 和 hooks_riverpod: ^2.0.0-dev.9。

import 'package:flutter/material.dart';
import 'package:hooks_riverpod/hooks_riverpod.dart';

void main() => runApp(ProviderScope(child: MyApp()));

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) => MaterialApp(title: 'Riverpod Spinner Demo',
      theme: ThemeData(primarySwatch: Colors.blue), home: MyHomePage());
}

class MyHomePage extends ConsumerWidget {

  @override
  Widget build(BuildContext context, WidgetRef ref) => Scaffold(
      appBar: AppBar(title: const Text('Riverpod Spinner Question'),),
      body: ref.watch(futureProvider).when(data: (data) => Column(
        children: [
          ElevatedButton(onPressed: () => ref.read(paramProvider.notifier).state = 'new value',
              child: const Text('pretend update')),
          Text(data)],
      ),
          error: (_,__) => const Text('something went wrong'),
          loading: () => const CircularProgressIndicator())
  );
}

final paramProvider = StateProvider((ref) => 'Initial value');

final futureProvider = FutureProvider.autoDispose<String>((ref) async {
  String parameter = ref.watch(paramProvider);
  return pretendApiCall(parameter);
});
Future<String> pretendApiCall(String parameter) async {
  await Future.delayed(const Duration(seconds: 3));
  return parameter;
}

Answer 1

啊。

var asyncValue = ref.watch(futureProvider);
return Scaffold(
  appBar: AppBar(title: const Text('Riverpod Spinner Question'),),
  body: asyncValue.when(data: (data) {
    if (asyncValue.isRefreshing) return const CircularProgressIndicator();
    return Column(
    children: [
      ElevatedButton(onPressed: () => ref.read(paramProvider.notifier).state = 'new value',
          child: const Text('pretend update')),
      Text(data)],
  );
  },