Flutter报错Undefined name 'mounted'，求修改方案实现内购

问题根源 #

mounted是StatefulWidget的State类专属属性，你的NavBar是StatelessWidget，没有这个属性，所以会报未定义错误。不需要额外导入任何包，只需要把组件改成StatefulWidget即可。

具体修改步骤 #

1. 将NavBar从StatelessWidget改为StatefulWidget，生成对应的_NavBarState类
2. 将状态变量（比如isSubscribed）和fetchOffers方法移到_NavBarState类中
3. 在State类中可直接访问mounted属性，无需额外处理

修改后的完整代码 #

import 'package:flutter/material.dart';
import 'package:AnyKnower/chatgpt.dart';
import 'package:AnyKnower/privacypolicy.dart';
import 'package:AnyKnower/purchase_api.dart';
import 'package:AnyKnower/utils.dart';
import 'package:glassfy_flutter/models.dart';
import 'package:provider/provider.dart';
import 'chat_screen.dart';
import 'package:page_transition/page_transition.dart';
import 'glassfy_provider.dart';

class NavBar extends StatefulWidget {
  const NavBar({super.key});

  @override
  State<NavBar> createState() => _NavBarState();
}

class _NavBarState extends State<NavBar> {
  bool isSubscribed = false;

  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: ListView(
        padding: EdgeInsets.zero,
        children: [
          ClipRRect(
            borderRadius: BorderRadius.only(
              topRight: Radius.circular(15),
            ),
            child: UserAccountsDrawerHeader(
              accountName: Text('AnyKnower'),
              accountEmail: Text(''),
              currentAccountPicture: CircleAvatar(
                child: ClipOval(
                  child: Image.asset('assets/logo4.jpg', width: 100, height: 100, fit: BoxFit.cover),
                ),
              ),
              decoration: BoxDecoration(
                image: DecorationImage(
                  image: AssetImage("assets/background1.jpg"),
                  fit: BoxFit.cover,
                ),
              ),
            ),
          ),
          ListTile(
            leading: Icon(Icons.chat_rounded,color: Colors.blueGrey,),
            title: Text("AnyKnower Chat"),
            onTap: () {
              Navigator.of(context).push(PageTransition(child: ChatScreen(), type: PageTransitionType.fade));
            }
          ),
          ListTile(
            leading: Icon(Icons.shopping_cart_outlined,color: Colors.blueGrey,),
            title: Text("The AnyKnower Shop"),
            onTap: () {
              fetchOffers();
            }
          ),
          ListTile(
            leading: Icon(Icons.chat_outlined,color: Colors.blueGrey,),
            title: Text("Beta Premium chat"),
            onTap: () {
              Navigator.of(context).push(PageTransition(child: chatgpt(), type: PageTransitionType.fade));
            }
          ),
          ListTile(
            leading: Icon(Icons.privacy_tip_outlined,color: Colors.blueGrey,),
            title: Text("Privacy Policy"),
            onTap: () {
              Navigator.of(context).push(PageTransition(child: privacypolicy(), type: PageTransitionType.fade));
            }
          ),
        ],
      )
    );
  }

  Future fetchOffers() async {
    final offerings = await PurchaseApi.fetchOffers();
    final offer = offerings.singleWhere((offering) => offering.offeringId == '100AnyKnowerCredit');
    if(!mounted) return;
    Utils.showSheet(
      context,
      (context) => PayWallWidget(
        title: 'Upgrade your plan',
        description: 'kkdkdd',
        offer: offer,
        onClickedSku: (sku) async {
          final transaction = await PurchaseApi.purchaseSku(sku);
          if (!mounted) return;
          if (transaction != null) {
            final provider = context.read<GlassfyProvider>();
            provider.add10Coins();
          }
          Navigator.pop(context);
        },
      )
    );
  }
}

关键修改点说明 #

• 转为StatefulWidget后，_NavBarState类拥有mounted属性，可判断当前Widget是否还挂载在Widget树上，避免异步请求完成后Widget已销毁导致的异常
• fetchOffers方法移到State类后，无需再传递context，直接使用State类的context即可
• 原代码中的mounted!改为!mounted，写法更简洁且符合Dart空安全规范

内容的提问来源于stack exchange，提问作者Android_devNL