错误：找不到吸气剂：颤动中的小部件

Question

我想问一下flutter，我无法解决代码，我从登录中获取数据，我想放入tuple2，如何将用户名从登录推送到tuple2？任何人都可以帮助我吗？

这是我的登录代码

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

import 'package:fluttertoast/fluttertoast.dart';
import 'package:testing/admin/portfolio_page.dart';
import 'package:testing/user/portfolio_page.dart';

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

String username = '';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Login Dengan MySql',
      home: MyHomePage(),
      routes: <String, WidgetBuilder>{
        '/PortfolioPage': (BuildContext context) => new PortfolioPage(
          username: username,
        ),
        // '/PortfolioPageUser': (BuildContext context) => new PortfolioPageUser(
        //   username: username,
        // ),
        '/MyHomePage': (BuildContext context) => new MyHomePage(),
      },
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  bool _isHidePassword = true;

  void _togglePassword() {
    setState(() {
      _isHidePassword = !_isHidePassword;
    });
  }

  TextEditingController user = new TextEditingController();
  TextEditingController pass = new TextEditingController();

  Future<List> _login() async {
    final response =
    await http.post("http://192.168.56.1/basic/loginmultiuser/login.php", body: {
      "username": user.text,
      "password": pass.text,
    });
    var datauser = json.decode(response.body);
    if (datauser.length == 0) {
      setState(() {
        tampil();
      });
    } else {
      if (datauser[0]['level'] == 'admin') {
        Navigator.pushReplacementNamed(context, '/PortfolioPage');
      } else if (datauser[0]['level'] == 'member') {
        Navigator.pushReplacementNamed(context, '/MemberPage');
      }

      setState(() {
        username = datauser[0]['username'];
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Login"),
      ),
      body: Padding(
        padding: const EdgeInsets.fromLTRB(25, 50, 25, 0),
        child: Center(
          child: Column(
            children: <Widget>[
              Padding(
                padding: const EdgeInsets.fromLTRB(18, 0, 18, 18),
                child: TextField(
                  controller: user,
                  decoration: InputDecoration(
                    //hintText: 'Username'

                    fillColor: Colors.lightGreen[40],
                    filled: true,
                    prefixIcon: Icon(
                      Icons.person,
                      color: Colors.blue,
                    ),
                    prefixStyle: TextStyle(
                        color: Colors.blue, fontWeight: FontWeight.w600),
                    labelText: "Username",
                    hintText: 'Username anda',
                    hintStyle: TextStyle(
                        color: Colors.black, fontWeight: FontWeight.w200),
                    labelStyle: TextStyle(
                        color: Colors.blue, fontWeight: FontWeight.w600),
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.circular(10),
                    ),
                  ),
                ),
              ),
              Padding(
                padding: const EdgeInsets.fromLTRB(18, 0, 18, 0),
                child: TextField(
                  controller: pass,
                  obscureText: _isHidePassword,
                  decoration: InputDecoration(
                    //hintText: 'Password'

                    fillColor: Colors.lightGreen[40],
                    filled: true,
                    prefixIcon: Icon(
                      Icons.lock,
                      color: Colors.blue,
                    ),
                    prefixStyle: TextStyle(
                        color: Colors.blue, fontWeight: FontWeight.w600),
                    labelText: "Password",
                    hintText: 'Password anda',
                    hintStyle: TextStyle(
                        color: Colors.black, fontWeight: FontWeight.w200),
                    labelStyle: TextStyle(
                        color: Colors.blue, fontWeight: FontWeight.w600),
                    border: OutlineInputBorder(
                      borderRadius: BorderRadius.circular(10),
                    ),
                    suffixIcon: GestureDetector(
                      onTap: () {
                        _togglePassword();
                      },
                      child: Icon(
                        _isHidePassword
                            ? Icons.visibility_off
                            : Icons.visibility,
                        color: _isHidePassword ? Colors.grey : Colors.blue,
                      ),
                    ),
                    isDense: true,

                  ),
                ),
              ),
              Padding(
                padding: const EdgeInsets.fromLTRB(0, 20, 0, 0),
                child: RaisedButton(
                  child: Text(
                    "Login",
                    style: TextStyle(fontSize: 20),
                  ),
                  padding: EdgeInsets.fromLTRB(60, 10, 60, 10),
                  textColor: Colors.white,
                  color: Colors.blue,
                  shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.all(Radius.circular(16.0))),
                  onPressed: () {
                    _login();
                  },
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }

  void tampil() {
    Fluttertoast.showToast(
        msg: "LOGIN GAGAL",
        toastLength: Toast.LENGTH_SHORT,
        gravity: ToastGravity.CENTER,
        timeInSecForIosWeb: 1,
        backgroundColor: Colors.red,
        textColor: Colors.white,
        fontSize: 16.0);
  }
}

这是我的 tuple2

import 'dart:developer';

import 'package:flutter/material.dart';
import 'package:testing/admin/portfolio_gallery_sub_page.dart';
import 'package:testing/admin/portfolio_tutorials_sub_page.dart';
import 'package:testing/components/portfolio_sliver_app_bar.dart';
import 'package:tuple/tuple.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';

import 'package:tuple/tuple.dart';

class PortfolioPage extends StatefulWidget {
  // PortfolioPage({Key key}) : super(key: key);
  PortfolioPage({this.username});
  final String username;
  @override
  _PortfolioPageState createState() => _PortfolioPageState();

}

class _PortfolioPageState extends State<PortfolioPage> {
    // String data(){
    //   return widget.username;
    // }
    // String get username => data();
  final List<Tuple2> _pages = [
    Tuple2('Tutorials', PortfolioTutorialsSubPage()),
    Tuple2('Tutorials', PortfolioTutorialsSubPage()),
    Tuple2('Gallery', Admin(username: widget.username)),
  ];


  int _selectedPage = 0;

  PageController _pageController = PageController();


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: NestedScrollView(
        headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
          return <Widget>[
            PortfolioSliverAppBar(_pages[_selectedPage].item1),
          ];
        },
        body: PageView(
          children: _pages.map<Widget>((Tuple2 page) => page.item2).toList(),
          onPageChanged: (index) {
            setState(() {
              _selectedPage = index;
            });
          },
          controller: _pageController,
        ),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(
            icon: Icon(Icons.video_library),
            title: Text('Tutorials'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.video_library),
            title: Text('Tutorials'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.image),
            title: Text('Gallery'),
          ),
        ],
        currentIndex: _selectedPage,
        onTap: (index) {
          setState(() {
            _selectedPage = index;
            _pageController.animateToPage(_selectedPage,
                duration: Duration(milliseconds: 300), curve: Curves.linear);
          });
        },
      ),
    );
  }


}

我的代码不起作用，因为 Tuple2('Gallery', Admin(用户名: widget.username)), 无法获取用户名，如何解决？

Answer 1

您应该将用户名作为arguments 传递给pushReplacementNamed。

在投资组合页面上，用户名可以通过ModalRoute.of(context).settings.arguments 获取，或者您可以使用onGenerateRoute 而不是routes 将传递用户名从参数添加到PortfolioPage 构造函数。

更多详情请查看this页面。

Answer 2

问题是当您定义和初始化变量“_pages”时，“小部件”不可用。要修复它，您可以覆盖“initState”并在其中设置变量“_pages”的值。

    late List<Tuple2> _pages;
    ...
    @override
    initState() {
       _pages = [
          Tuple2('Tutorials', PortfolioTutorialsSubPage()),
          Tuple2('Tutorials', PortfolioTutorialsSubPage()),
          Tuple2('Gallery', Admin(username: widget.username)),
       ];
       super.initState();
   }