Question

我的Flutter应用中出现此错误：

在null上调用了getter'auth'。接收者：null 尝试致电：auth

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:smartbin/services/provider.dart';
import 'package:auro_avatar/auro_avatar.dart';

class Profile extends StatelessWidget {


  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
            title: Text('Profile'),
            centerTitle: true,
            backgroundColor: Colors.green[800]),
        backgroundColor: Colors.green[400],
        body: Container(
          padding: EdgeInsets.all(20),
          child: Column(children: <Widget>[
            InitialNameAvatar(
              "",
              circleAvatar: true,
            ),
            SizedBox(
              height: 20,
            ),

//提出了用于编辑的按钮

            RaisedButton(
              onPressed: () {},
              child: new Row(
                mainAxisAlignment: MainAxisAlignment.center,
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  new Text('Edit'),
                  new Icon(Icons.edit),
                ],
              ),
              color: Colors.greenAccent,
            ),

//将来的构建器，用于从Firebase导入数据

            FutureBuilder(
              future: Provider.of(context).auth.getCurrentUID(),
              builder: (context, snapshot){
                if (snapshot.connectionState == ConnectionState.done)
                  {
                    return Text("${snapshot.hasData}");
                  }
              },
            ),

//自定义窗口小部件以制作图标文字

            buildProfile(
              icon: Icons.person,
              text: 'Name:',
              subtext: '',
            ),
            SizedBox(height: 30),
            buildProfile(
              icon: Icons.email,
              text: "Email:",
              subtext: '',
            )
          ]),
        ));
  }
}

//自定义小部件

class buildProfile extends StatelessWidget {
  IconData icon;
  String text;
  String subtext;
  buildProfile({this.text, this.icon, this.subtext});

  @override
  Widget build(BuildContext context) {
    return Row(
      children: <Widget>[
        Icon(icon),
        SizedBox(
          width: 10,
        ),
        Text(text,
            style: TextStyle(
              fontSize: 20,
              fontFamily: 'Solway',
              fontWeight: FontWeight.bold,
            )),
        SizedBox(
          width: 10,
        ),
        Text(subtext,
            style: TextStyle(
              fontSize: 20,
              fontFamily: 'Solway',
              fontWeight: FontWeight.bold,
            )),
      ],
    );
  }
}

该错误来自将来的构建器，该认证称auth被调用为null。我希望你们能帮助我。谢谢。

修改提供程序代码在这里。

import 'package:firebase_auth/firebase_auth.dart';
import 'package:smartbin/services/auth.dart';
import 'package:flutter/material.dart';

class Provider extends InheritedWidget {
  final AuthService auth;

  Provider({Key key, Widget child, this.auth}) : super(key: key, child: child);

  @override
  bool updateShouldNotify(InheritedWidget oldWidget) {
    return true;
  }

  static Provider of(BuildContext context) =>
      // ignore: deprecated_member_use
      (context.dependOnInheritedWidgetOfExactType<Provider>());
}

Answer 1

问题出在您的FutureBuilder，您致电.auth而没有提供者。你做到了

Provider.of(context).auth.getCurrentUID()

，表示您未指定任何Provider。您应该这样访问您的提供商

Provider.of<AuthProvider>(context).auth.getCurrentUID() //replace AuthProvider with your provider's name

Answer 2

您必须指定提供商

Provider.of<AuthProvider>(context).auth.getCurrentUID()

getter'auth'在null上被调用。接收方：null尝试调用：auth

2 个答案: