NoSuchMethodError：在 null 上调用了方法“createUserWithEmailAndPassword”

Question

import 'package:flutter/material.dart';
import 'package:Trial/app/services/auth.dart';

class RegisterForm extends StatefulWidget {
  RegisterForm({@required this.auth});
  final AuthBase auth;

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

class _RegisterFormState extends State<RegisterForm> {
  // final TextEditingController _firstnameController = TextEditingController();
//  final TextEditingController _lastnameController = TextEditingController();
  final TextEditingController _emailController = TextEditingController();
  final TextEditingController _passwordController = TextEditingController();

  //String get _fname => _firstnameController.text;
  //String get _lname => _lastnameController.text;
  String get _email => _emailController.text;
  String get _password => _passwordController.text;

  void _register() async {
    try {
      print('$_email & $_password');
      await widget.auth.createUserWithEmailAndPassword(_email, _password);
      Navigator.of(context).pop();
    } catch (e) {
      print(e.toString());
    }
  }

  List<Widget> _buildChildren() {
    return [
      TextField(
        decoration: InputDecoration(labelText: 'First Name', hintText: 'John'),
      ),
      TextField(
        decoration: InputDecoration(labelText: 'Last Name', hintText: 'Doe'),
      ),
      TextField(
        controller: _emailController,
        decoration:
            InputDecoration(labelText: 'Email', hintText: 'yourmail@mail.com'),
        onChanged: (_email) => _updateState(),
      ),
      TextField(
        controller: _passwordController,
        decoration: InputDecoration(
          labelText: 'Password',
        ),
        obscureText: true,
        onChanged: (_password) => _updateState(),
      ),
      TextField(
        decoration:
            InputDecoration(labelText: 'Account No.', hintText: '123456789-0'),
      ),
      SizedBox(
        height: 5.0,
      ),
      TextField(
        decoration: InputDecoration(labelText: ' MAP LOCATION'),
      ), //LOCATION CAPTURE GOING HERE
      RaisedButton(
        child: Text('Register'),
        onPressed: _register,
      ),
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(16.0),
      child: ListView(
        children: _buildChildren(),
      ),
    );
  }

  void _updateState() {
    setState(() {});
  }
}

我得到的错误是这样的

I/flutter (6751): NoSuchMethodError: 方法 'createUserWithEmailAndPassword' 在 null 上被调用。

I/flutter (6751)：接收器：null ? I/flutter (6751)：尝试调用：createUserWithEmailAndPassword("test@gmail.com", "password")

我在颤振和火力基地相当新。我正在尝试注册用户，但 auth 类中的方法传递为 null。

import 'package:Trial/app/services/auth.dart';
import 'package:Trial/app/signin/register_form.dart';
import 'package:flutter/material.dart';

class RegisterPage extends StatelessWidget {
  RegisterPage({@required this.auth});
  final AuthBase auth;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Register Account'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Card(child: RegisterForm(auth: auth)),
      ),
    );
  }
}

这将是我的身份验证文件

 import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/foundation.dart';

class User {
  User({@required this.uid});
  final String uid;
}

abstract class AuthBase {
  Stream<User> get onAuthStateChanged;
  Future<User> currentUser();
  Future<User> signInAnonymously();
  Future<User> signInWithEmailAndPassword(String email, String password);
  Future<User> createUserWithEmailAndPassword(String email, String password);
  Future<void> signOut();
}

class Auth implements AuthBase {
  /*to check to see if anyone is signed in*/
  final _firebaseAuth = FirebaseAuth.instance;

  User _userFromFirebsae(FirebaseUser user) {
    if (user == null) {
      return null;
    }
    return User(uid: user.uid);
  }

  @override
  Stream<User> get onAuthStateChanged {
    return _firebaseAuth.onAuthStateChanged.map(_userFromFirebsae);
  }

  @override
  Future<User> currentUser() async {
    final user = await _firebaseAuth.currentUser();
    return _userFromFirebsae(user);
  }

/*to sign in without logining in*/
  @override
  Future<User> signInAnonymously() async {
    final authResult = await _firebaseAuth.signInAnonymously();
    return _userFromFirebsae(authResult.user);
  }

  @override
/*to sign in with email*/
  Future<User> signInWithEmailAndPassword(String email, String password) async {
    final authResult = await _firebaseAuth.signInWithEmailAndPassword(
        email: email, password: password);
    return _userFromFirebsae(authResult.user);
  }

//create email
  @override
  Future<User> createUserWithEmailAndPassword(
      String email, String password) async {
    final authResult = await _firebaseAuth.createUserWithEmailAndPassword(
        email: email, password: password);
    return _userFromFirebsae(authResult.user);
  }

/*to sign out of app*/
  @override
  Future<void> signOut() async {
    await _firebaseAuth.signOut();
  }
}

Answer 1

您从未在以下位置初始化auth：

class RegisterPage extends StatelessWidget {
  RegisterPage({@required this.auth});
  final AuthBase auth;
  ...

您需要将其初始化为：

  final FirebaseAuth auth = FirebaseAuth.instance;