即使在多个页面路由之后也保持变量值，除非在 flutter

问题描述

我有一个包含许多菜单项的抽屉小部件。我有一个变量来处理选定的项目编号。我用 1 启动它来选择加载的第一个项目。当我选择另一个 MenuItem 时，该值会更改为相应的项目编号。当我从 Menuitem 页面重定向/重新路由到抽屉页面时，它再次显示第一个 Menuitem。我希望变量值保留并显示我选择的菜单项。

  import 'package:country_code_picker/country_localizations.dart';
import 'package:Flutter/material.dart';
import 'package:scoped_model/scoped_model.dart';
import 'package:wyiin_admin_portal/admin_screens/access_management.dart';
import 'package:wyiin_admin_portal/admin_screens/brand_management_main.dart';
import 'package:wyiin_admin_portal/admin_screens/language_management_main.dart';
import 'package:wyiin_admin_portal/admin_screens/product_category_management_main.dart';
import 'package:wyiin_admin_portal/admin_screens/promotion_management_main.dart';
import 'package:wyiin_admin_portal/login/password_reset.dart';
import 'package:wyiin_admin_portal/model/BrandMgmtScreens.dart';
import 'package:wyiin_admin_portal/work_in_progress.dart';

class MyAppDrawer extends StatelessWidget {
  final appTitle = 'WYIIN';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      supportedLocales: [
        const Locale('en','US'),],debugShowCheckedModeBanner: false,localizationsDelegates: [CountryLocalizations.delegate],title: appTitle,home: MyDrawer(title: appTitle),theme: ThemeData(primaryColor: Color.fromrGBO(255,255,1)),);
  }
}

class MyDrawer extends StatefulWidget {
  final String title;
  final int destination;

  MyDrawer({Key key,this.title,this.destination}) : super(key: key);

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

class _MyHomePageState extends State<MyDrawer> {
  var _selectedDestination;

  @override
  Widget build(BuildContext context) {
    print(_selectedDestination);
    setState(() {
      _selectedDestination =
          _selectedDestination == null ? 1 : _selectedDestination;
    });
    print(_selectedDestination);
    return ScopedModelDescendant<Screen>(builder: (_,child,model) {
      return Row(
        children: [
          Container(
            width: 255,child: Drawer(
              child: Container(
                color: Color.fromrGBO(42,48,66,1),child: ListView(
                  padding: EdgeInsets.zero,children: <Widget>[
                    Padding(
                      padding: const EdgeInsets.all(16.0),child: Text('WYiiN',style: TextStyle(
                              fontSize: 18,fontWeight: FontWeight.bold,color: Colors.white)),),Padding(
                      padding: const EdgeInsets.only(left: 15,top: 4),child: Text('Menu',style: TextStyle(
                              fontSize: 14,fontWeight: FontWeight.w600,color: Color.fromrGBO(106,113,135,1))),ListTile(
                      visualDensity: VisualDensity(horizontal: -4,vertical: 0),contentPadding: const EdgeInsets.only(left: 15,leading: _selectedDestination == 6
                          ? Image.asset(
                              'assets/images/Brand Management_active.png')
                          : Image.asset('assets/images/Brand Management.png'),title: Text('Brand management',style: TextStyle(
                            fontSize: 13,fontWeight: FontWeight.w300,color: _selectedDestination == 6
                                ? Colors.white
                                : Color.fromrGBO(106,)),selected: _selectedDestination == 6,onTap: () {
                        if (model.showScreen == true) {
                          model.screenDecide();
                        }
                        selectDestination(6);
                      },ListTile(
                        visualDensity:
                            VisualDensity(horizontal: -4,leading: _selectedDestination == 8
                            ? Image.asset(
                                'assets/images/product_category_management_active.png')
                            : Image.asset(
                                'assets/images/product_category_management.png'),title: Text('Product Category management',style: TextStyle(
                              fontSize: 13,color: _selectedDestination == 8
                                  ? Colors.white
                                  : Color.fromrGBO(106,selected: _selectedDestination == 8,onTap: () {
                          if (model.showProdCatScreen == true) {
                            model.screenDecideProdCat();
                          }
                          selectDestination(8);
                        }),leading: _selectedDestination == 9
                            ? Image.asset(
                                'assets/images/language_management_active.png')
                            : Image.asset(
                                'assets/images/language_management.png'),title: Text('Language Management',color: _selectedDestination == 9
                                  ? Colors.white
                                  : Color.fromrGBO(106,selected: _selectedDestination == 9,onTap: () {
                          if (model.showLangMgmtScreen == true) {
                            model.screenDecideLangMgmt();
                          }
                          selectDestination(9);
                        }),VerticalDivider(
            width: 1,thickness: 1,Expanded(
            child: Scaffold(
                body: _selectedDestination == 6
                    ? BrandMgmtMain()
                    : _selectedDestination == 9
                        ? LanguageMgmtMain()
                        : _selectedDestination == 7
                            ? AccessMgmt()
                            : _selectedDestination == 8
                                ? ProdCatMgmtMain()
                                : _selectedDestination == 5
                                    ? PromotionMgmtMain()
                                    : _selectedDestination == 2
                                        ? WorkInProgress()
                                        : _selectedDestination == 10
                                            ? PassReset()
                                            : _selectedDestination == 1
                                                ? WorkInProgress()
                                                : WorkInProgress()),);
    });
  }

  void selectDestination(int index) {
    setState(() {
      _selectedDestination = index;
      print(_selectedDestination);
    });
  }
}

void body(int selection) {}

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）