无法访问我的小部件颤动的变量

问题描述 投票：0回答：3

我尝试为我的应用程序制作一个简单的个人资料页面，但我不完全知道该怎么做。

我想打电话时遇到错误

'${widget.user['first_name']}'

在我的个人资料小部件中：

NoSuchMethodError (NoSuchMethodError: The method '[]' was called on null. Receiver: null Tried calling: []("first_name"))

我的主页是一个包含 2 个小部件的 PageView。

// ignore_for_file: prefer_const_constructors, prefer_const_literals_to_create_immutables

import 'dart:convert';

import 'package:clic_ads/Login/apiClient.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../Composants/appbar.dart';
import '../Login/login.dart';
import 'notifs.dart';
import 'profil.dart';

class MainPage extends StatefulWidget {
  final dynamic user;
  const MainPage({super.key, this.user});
  @override
  _MainPageState createState() => _MainPageState();
}

class _MainPageState extends State<MainPage> {
  final Api _apiClient = Api();
  dynamic user;
  final PageController _controller = PageController(
    initialPage: 0,
  );
  int activePage = 0;

  @override
  Future<void> dispose() async {
    _controller.dispose();
    super.dispose();
  }
  
@override
  void initState() {
    super.initState();
  }
  void bottomTapped(int index) {
    setState(() {
      activePage = index;
      _controller.animateToPage(index,
          duration: Duration(milliseconds: 500), curve: Curves.ease);
    });
  }

  @override
  Widget build(BuildContext context) {
    Future<void> getUser() async {
      SharedPreferences prefs = await SharedPreferences.getInstance();
      var token = prefs.getString('token');
      this.user = await _apiClient.user(token!);
      print(user);
      return user ;
    }
    getUser();
    return Scaffold(
      appBar: PreferredSize(
          preferredSize:
              Size.fromHeight(MediaQuery.of(context).size.height * 0.07),
          child: TopAppbar()),
      bottomNavigationBar: BottomNavigationBar(
        type: BottomNavigationBarType.fixed,
        currentIndex: activePage,
        backgroundColor: const Color(0xffC64C4E),
        selectedItemColor: Colors.white,
        unselectedItemColor: Colors.white.withOpacity(.55),
        selectedFontSize: 14,
        unselectedFontSize: 14,
        onTap: (value) {
          bottomTapped(value);
        },
        items: [
          BottomNavigationBarItem(
            label: 'Notifs',
            icon: Icon(Icons.view_list),
          ),
          BottomNavigationBarItem(
            label: 'Profil',
            icon: Icon(
              Icons.account_circle,
            ),
          ),
        ],
      ),
      backgroundColor: const Color(0xffEEEEEE),
      body: PageView(
        onPageChanged: (index) {
          setState(() {
            activePage = index;
          });
        },
        controller: _controller,
        children: [Notifs(), Profil(user: this.user)],
      ),
    );
  }
  
}

我的第一个小部件是一个显示通知的小部件：


// ignore_for_file: prefer_const_constructors, prefer_const_literals_to_create_immutables, unnecessary_new

import 'package:clic_ads/Login/apiClient.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

class Notifs extends StatefulWidget {
final dynamic user;
const Notifs({super.key, this.user});

@override
State\<Notifs\> createState() =\> \_NotifsState();
}

class \_NotifsState extends State\<Notifs\> {
final Api \_apiClient = Api();
dynamic user;
@override
Widget build(BuildContext context) {
double deviceWidth = MediaQuery.of(context).size.width;
double deviceHeight = MediaQuery.of(context).size.height;
Future\<void\> getUser() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var token = prefs.getString('token');
this.user = await \_apiClient.user(token!);
print(user);
return user ;
}
getUser();

    return ListView.builder(
      itemCount: 10,
      itemBuilder: (BuildContext context, int index) {
        return Column(
          children: [
            new Container(
              decoration: new BoxDecoration(
                  color: Color.fromARGB(255, 255, 255, 255),
                  borderRadius: new BorderRadius.only(
                    topRight: const Radius.circular(15.0),
                    topLeft: const Radius.circular(15.0),
                  )),
              margin: EdgeInsets.only(
                  top: deviceWidth * 0.03,
                  right: deviceWidth * 0.05,
                  left: deviceWidth * 0.05),
              height: deviceHeight * 0.148,
              alignment: Alignment.centerLeft,
              child: Row(
                children: [
                  Container(
                    decoration: new BoxDecoration(
                        color: const Color(0xffC64C4E),
                        borderRadius: new BorderRadius.only(
                          topLeft: const Radius.circular(15.0),
                        )),
                    width: deviceWidth * 0.12,
                    child: Center(
                      child: FittedBox(
                        child: Text(
                          'CU',
                          style: TextStyle(
                              fontSize: deviceWidth * 0.06,
                              fontWeight: FontWeight.bold,
                              color: Colors.white),
                        ),
                      ),
                    ),
                  ),
                  Padding(
                    padding: EdgeInsets.all(deviceWidth * 0.02),
                    child: SizedBox(
                      width: deviceWidth * 0.73,
                      child: Column(
                        children: [
                          Row(
                            children: [
                              Text('17:24',
                                  style: TextStyle(
                                      fontSize: deviceWidth * 0.04,
                                      color: const Color(0xffC64C4E),
                                      fontWeight: FontWeight.w600)),
                              Spacer(),
                              Text('20/10/2022',
                                  style: TextStyle(
                                      fontSize: deviceWidth * 0.04,
                                      color: const Color(0xffC64C4E),
                                      fontWeight: FontWeight.w600))
                            ],
                          ),
                          Padding(
                            padding: EdgeInsets.all(deviceWidth * 0.02),
                            child: Row(
                              children: [
                                Icon(Icons.person),
                                Text('DUPOND Martin (M.)',
                                    style: TextStyle(
                                        fontSize: deviceWidth * 0.035,
                                        fontWeight: FontWeight.w500))
                              ],
                            ),
                          ),
                          Padding(
                            padding: EdgeInsets.all(deviceWidth * 0.02),
                            child: Row(
                              children: [
                                Icon(
                                  Icons.book,
                                ),
                                Text('CU01201222U0009',
                                    style: TextStyle(
                                        fontSize: deviceWidth * 0.035,
                                        fontWeight: FontWeight.w500))
                              ],
                            ),
                          )
                        ],
                      ),
                    ),
                  )
                ],
              ),
            ),
            Container( 
                color: const Color(0xffC64C4E),
                height: 3,
                width: deviceWidth * 0.90)
          ],
        );
      },
    );

}
}

我想显示用户详细信息的第二个小部件在这里：


// ignore_for_file: prefer_const_constructors, prefer_const_literals_to_create_immutables

import 'package:clic_ads/Login/apiClient.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

class Profil extends StatefulWidget {
final dynamic user;
const Profil({super.key, this.user});
@override
State\<Profil\> createState() =\> \_ProfilState();
}

class \_ProfilState extends State\<Profil\> {

// final Api \_apiClient = Api();
@override
void initState() {
super.initState();
}

@override
Widget build(BuildContext context) {

    // Future<void> getUser() async {
    //   SharedPreferences prefs = await SharedPreferences.getInstance();
    //   var token = prefs.getString('token');
    //   user = await _apiClient.user(token!);
    //   print(user['data']);
    // }
    
    // getUser();
    // print(user);
    double deviceWidth = MediaQuery.of(context).size.width;
    double deviceHeight = MediaQuery.of(context).size.height;
    
    return Padding(
      padding: EdgeInsets.all(deviceWidth * 0.05),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text('Profil',
              style: TextStyle(
                  fontSize: deviceWidth * 0.06, fontWeight: FontWeight.w500)),
          Padding(
            padding: EdgeInsets.only(left: deviceWidth * 0.05),
            child: Row(
              children: [
                Icon(
                  Icons.account_circle,
                  size: deviceWidth * 0.3,
                ),
                Padding(
                  padding: EdgeInsets.only(left: deviceWidth * 0.05),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Row(
                        children: [
                          Text('${widget.user['first_name']}',
                              style: TextStyle(
                                  fontSize: deviceWidth * 0.04,
                                  fontWeight: FontWeight.w500)),
                          SizedBox(width: 10),
                          Text('${widget.user['last_name']}',
                              style: TextStyle(
                                  fontSize: deviceWidth * 0.04,
                                  fontWeight: FontWeight.w500))
                        ],
                      ),
                      SizedBox(
                        height: 15,
                      ),
                      Text('${widget.user['email']}',
                          style: TextStyle(
                              fontSize: deviceWidth * 0.04,
                              fontWeight: FontWeight.w500))
                    ],
                  ),
                )
              ],
            ),
          ),
          Text('Paramètres',
              style: TextStyle(
                  fontSize: deviceWidth * 0.06, fontWeight: FontWeight.w500))
        ],
      ),
    );

}
}

我希望在我的个人资料页面上显示我的用户信息

flutter dart text widget nosuchmethoderror
3个回答
0
投票

尝试接受 null 就像

'${widget.user?['first_name']}'
0
投票

getUser();
方法是异步方法，但在
_MainPageState.build
方法执行期间不会等待它。

因此，当执行 

children: [Notifs(), Profil(user: this.user)],
行时，
user
类成员未初始化。

所以您可能想使用 FutureBuilder 来等待未来并获得结果。

此方案需要将

getUser
方法调整为类方法，并返回
Future<dynamic>
值供后续使用：

class _NotifsState extends State<Notifs> {
...
Future<dynamic> getUser() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
var token = prefs.getString('token');
this.user = await _apiClient.user(token!);
print(user);
return user ;
}

@override
  Widget build(BuildContext context) {
...
children: [Notifs(), FutureBuilder<dynamic>(
        future: getUser(), 
        builder: (c, snapshot) => snapshot.hasData
            ? Profil(user: snapshot.data) 
            : const CircularProgressIndicator())
],
}
}
0
投票

在第二个代码示例的 

'${widget.user['first_name']}'
行中，用户信息是从哪里获取的？对我来说，似乎没有当前用户的实例可以从中获取信息。

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