使用带有 Flutter 后退按钮的 onGenerateRoute 时断言失败

Posted 2023-02-23

【中文标题】使用带有 Flutter 后退按钮的 onGenerateRoute 时断言失败

【英文标题】：Failed assertion when using onGenerateRoute with Flutter back button

【发布时间】：2019-08-14 00:52:34

【问题描述】：

我正在使用 MaterialApp 中的 onGenerateRoute 在我的颤振应用中实现导航。

对于其中一条路线，当我按下 Flutter 在 Appbar 中提供的后退按钮时出现此错误。

E/flutter (22996): [错误:flutter/lib/ui/ui_dart_state.cc(148)] 未处理的异常：断言失败：布尔表达式不得 空

E/flutter (22996): #0 ModalRoute.willPop （包：flutter/src/widgets/routes.dart）E/flutter（22996）：

E/flutter (22996): #1 NavigatorState.maybePop (包:flutter/src/widgets/navigator.dart:1964:57) E/flutter (22996):

E/flutter (22996): #2 Navigator.maybePop (包:flutter/src/widgets/navigator.dart:1291:34)

E/flutter (22996)：#3 BackButton.build。 (package:flutter/src/material/back_button.dart:91:19)

你能帮我理解什么是错的吗？

我的路线设置 ->

  Route<dynamic> routes(RouteSettings settings) 
    switch (settings.name) 
      case '/':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return HomePage();
          ,
        );
        break;
      case '/contactlist':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return FriendsList();
          ,
        );
        break;
      case '/ChatroomFormAdd':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return const ChatroomInfo(
                mode: 'Add');
          ,
        );
        break;
      case '/ChatroomFormEdit':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return const ChatroomInfo(
                mode: 'Edit');
          ,
        );
        break;
      case '/ChatroomFormView':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return const ChatroomInfo(
                mode: 'View');
          ,
        );
        break;
      case '/ChatroomFormApprove':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return const ChatroomInfo(
                mode: 'Approve');
          ,
        );
        break;
      case '/errorscreen':
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return ErrorScreen();
          ,
        );
        break;
      default:
        return MaterialPageRoute<dynamic>(
          builder: (BuildContext context) 
            return ChatDetail(chatroomID: chatroomID);
          ,
        );
        break;
    
  

当我从以下路线返回时，返回按钮适用于预期的所有路线：

Navigator.of(context).pushNamed('/ChatroomFormView');

【参考方案1】：

您使用了WillPopScope 小部件吗？如果是这样，您需要提供一个将Future<boolean> 返回到onWillPop 参数的函数。

WillPopScope(
      onWillPop: ()  
        //need to return Future<bool> here