我正在努力学习Flutter 动.我开始了"了解Flutter 翼的Firebase"教程.
我在本教程的第5步(添加RSVP功能)结束时收到Provider 错误. https://firebase.google.com/codelabs/firebase-get-to-know-flutter?authuser=0#4个
将以下代码添加到HOPE_Page.dart文件中时，会出现以下错误.
谢谢.
// Add from here
Consumer<ApplicationState>(
builder: (context, appState, _) => AuthFunc(
loggedIn: appState.loggedIn,
signOut: () {
FirebaseAuth.instance.signOut();
}),
),
// to here
希望页面dart
import 'package:firebase_auth/firebase_auth.dart' // new
hide EmailAuthProvider, PhoneAuthProvider; // new
import 'package:flutter/material.dart'; // new
import 'package:provider/provider.dart'; // new
import 'app_state.dart'; // new
import 'src/authentication.dart'; // new
import 'src/widgets.dart';
class HomePage extends StatelessWidget {
const HomePage({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Firebase Meetup'),
),
body: ListView(
children: <Widget>[
Image.asset('assets/codelab.png'),
const SizedBox(height: 8),
const IconAndDetail(Icons.calendar_today, 'October 30'),
const IconAndDetail(Icons.location_city, 'San Francisco'),
// Add from here
Consumer<ApplicationState>(
builder: (context, appState, _) => AuthFunc(
loggedIn: appState.loggedIn,
signOut: () {
FirebaseAuth.instance.signOut();
}),
),
// to here
const Divider(
height: 8,
thickness: 1,
indent: 8,
endIndent: 8,
color: Colors.grey,
),
const Header("What we'll be doing"),
const Paragraph(
'Join us for a day full of Firebase Workshops and Pizza!',
),
],
),
);
}
}
错误代码:
This app is linked to the debug service: ws://127.0.0.1:59701/r_M_M0NpAZc=/ws
Debug service listening on ws://127.0.0.1:59701/r_M_M0NpAZc=/ws
Connecting to VM Service at ws://127.0.0.1:59701/r_M_M0NpAZc=/ws
══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following ProviderNotFoundException was thrown building Consumer<ApplicationState>(dirty):
Error: Could not find the correct Provider<ApplicationState> above this Consumer<ApplicationState>
Widget
This happens because you used a `BuildContext` that does not include the provider
of your choice. There are a few common scenarios:
- You added a new provider in your `main.dart` and performed a hot-reload.
To fix, perform a hot-restart.
- The provider you are trying to read is in a different route.
Providers are "scoped". So if you insert of provider inside a route, then
other routes will not be able to access that provider.
- You used a `BuildContext` that is an ancestor of the provider you are trying to read.
Make sure that Consumer<ApplicationState> is under your MultiProvider/Provider<ApplicationState>.
This usually happens when you are creating a provider and trying to read it immediately.
For example, instead of:
Widget build(BuildContext context) {
return Provider<Example>(
create: (_) => Example(),
// Will throw a ProviderNotFoundError, because `context` is associated
// to the widget that is the parent of `Provider<Example>`
child: Text(context.watch<Example>().toString()),
);
}
consider using `builder` like so:
Widget build(BuildContext context) {
return Provider<Example>(
create: (_) => Example(),
// we use `builder` to obtain a new `BuildContext` that has access to the provider
builder: (context, child) {
// No longer throws
return Text(context.watch<Example>().toString());
}
);
}
If none of these solutions work, consider asking for help on StackOverflow:
https://stackoverflow.com/questions/tagged/flutter
The relevant error-causing widget was:
Consumer<ApplicationState>
Consumer:file:///D:/flutter_projeler/flutter-codelabs/firebase-get-to-know-flutter/step_02/lib/home_page.dart:26:11
When the exception was thrown, this was the stack:
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 294:3 throw_
packages/provider/src/provider.dart 343:7 _inheritedElementOf
packages/provider/src/provider.dart 293:30 of
packages/provider/src/consumer.dart 181:16 buildWithChild
packages/nested/nested.dart 259:41 build
packages/flutter/src/widgets/framework.dart 5541:22 build
packages/nested/nested.dart 279:18 build
packages/flutter/src/widgets/framework.dart 5471:15 performRebuild
packages/flutter/src/widgets/framework.dart 5187:7 rebuild
packages/flutter/src/widgets/framework.dart 2895:18 buildScope
packages/flutter/src/widgets/binding.dart 984:9 drawFrame
packages/flutter/src/rendering/binding.dart 457:5 [_handlePersistentFrameCallback]
packages/flutter/src/scheduler/binding.dart 1325:7 [_invokeFrameCallback]
packages/flutter/src/scheduler/binding.dart 1255:9 handleDrawFrame
packages/flutter/src/scheduler/binding.dart 1113:5 [_handleDrawFrame]
lib/_engine/engine/platform_dispatcher.dart 1274:5 invoke
lib/_engine/engine/platform_dispatcher.dart 248:5 invokeOnDrawFrame
lib/_engine/engine/initialization.dart 186:36 <fn>
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 574:37 _checkAndCall
dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 579:39 dcall
════════════════════════════════════════════════════════════════════════════════════════════════════
Application finished.
Exited (-1).```