提供者问题：找不到正确的提供者<auth></auth>

Question

我永久遇到这个问题：

未处理的异常：错误：在此注册小部件上方找不到正确的提供程序

由于我正在尝试实现用户身份验证，因此存在此错误。

这是我的代码：

import 'package:flutter/material.dart';
import 'konto.dart';
import 'package:studyIT/providers/auth.dart';
import 'package:provider/provider.dart';

class Register extends StatefulWidget {
  @override
  _RegisterAnsichtState createState() => _RegisterAnsichtState();
}

class _RegisterAnsichtState extends State<Register> {
  final _formKey = GlobalKey<FormState>();
  Map<String, String> _authData = {
    'email': '',
    'passwort': '',
  };
  var _isLoading = false;
  Future<void> _submit() async {
    if (!_formKey.currentState.validate()) {
      // Invalid!
      return;
    }
    _formKey.currentState.save();
    setState(() {
      _isLoading = true;
    });
    await Provider.of<Auth>(context, listen: false).registrieren(
      _authData['email'],
      _authData['password'],
    );
    setState(() {
      _isLoading = false;
    });
  }

  @override
  Widget build(BuildContext build) {
    return Scaffold(body: Builder(builder: (BuildContext context) {
      return Form(
          key: _formKey,
          child: Padding(
            padding: const EdgeInsets.all(50),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                TextFormField(
                  onChanged: (value) {
                    _authData['email'] = value;
                  },
                  validator: (value) {
                    if (value.isEmpty ||
                        !value.contains('@student.tgm.ac.at')) {
                      return "Ungültig";
                    }
                  },
                  keyboardType: TextInputType.text,
                  autocorrect: false,
                  decoration: InputDecoration(
                    labelText: 'E-Mail',
                    border: OutlineInputBorder(),
                  ),
                ),
                TextFormField(
                  decoration: InputDecoration(
                    labelText: 'Passwort',
                    border: OutlineInputBorder(),
                  ),
                  obscureText: true,
                  onChanged: (value) {
                    _authData['passwort'] = value;
                  },
                  validator: (value) {
                    if (value.isEmpty || value.length < 8) {
                      return "Zu kurz";
                    }
                  },
                ),
                TextFormField(
                    decoration: InputDecoration(
                      labelText: 'Passwort wiederholen',
                      border: OutlineInputBorder(),
                    ),
                    obscureText: true,
                    validator: (value) {
                      if (value != _authData['passwort']) {
                        return "Ungültige Passwörter";
                      }
                    }),
                SizedBox(width: 25),
                RaisedButton(
                  color: Colors.blue,
                  textColor: Colors.white,
                  child: Text('Registrieren'),
                  onPressed: () => _submit(),
                  //  {addName(_name)},
                )
              ],
            ),
          ));
    }));
  }
}

而主要的class在这里：

import 'package:flutter/material.dart';
import 'package:studyIT/RegisterAnsicht.dart';
import 'package:studyIT/providers/auth.dart';
import 'package:provider/provider.dart';
import 'package:studyIT/providers/test.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: Register(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
        create: (BuildContext context) {
          Auth();
        },
        child: MaterialApp(
          home: Register(),
        ));
  }
}

我不知道我能做些什么来解决这个错误？ 任何时候我尝试一些我都不起作用的东西。

Answer 1

这是因为您的MyHomePage() class 未在main.dart中说明。 实际上你可以摆脱这个 class （因为它没有工作）并在main.dart中用ChangeNotifierProvider包装class Register()