flutter - 如何在 onGenerateRoute 中使用 provider？

Question

如何在 onGenerateRoute 中使用我的 UserProvider？
我想检查用户是否是使用 UserProvider.isLogged() 的记录器，但是当我尝试获取 Userprovider 时，我必须传递我在路由器中没有的上下文。

我已经尝试将 generateRoute 更改为非静态并通过构造函数将上下文传递给 Router 但它抛出错误。

main.dart

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {

    return MultiProvider(
      providers: <SingleChildCloneableWidget>[
        ChangeNotifierProvider(builder: (_) => BottomNavigationBarProvider()),
        ChangeNotifierProvider(builder: (_) => UserProvider()),
      ],
      child: MaterialApp(
      initialRoute: '/',
      onGenerateRoute: Router.generateRoute,
      title: 'Title,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
    ),);

}
}

路由器.dart

class Router {

  static Route<dynamic> generateRoute(RouteSettings settings) {
    switch (settings.name) {
      case '/':
        return MaterialPageRoute(builder: (_) => HomePage());
        break;
      case '/login':
        return MaterialPageRoute(builder: (_) => LoginPage());
        break;
      case '/register':
        return MaterialPageRoute(builder: (_) => RegisterPage());
        break;
      case '/terms':
        return MaterialPageRoute(builder: (_) => TermsPage());
        break;
      case '/home':
        return MaterialPageRoute(builder: (_) {
          return HomePage();
        });
        break;
      default:
        return MaterialPageRoute(
            builder: (_) => Scaffold(
                  body: Center(
                      child: Text('No route defined for ${settings.name}')),
                ));
        break;
    }
  }
}

===我的尝试===

main.dart

onGenerateRoute: Router(context).generateRoute,

路由器.dart

class Router {
  Router(this.context);

  BuildContext context;

  Route<dynamic> generateRoute(RouteSettings settings) {
    final UserProvider userProvider = Provider.of<UserProvider>(context);
     userProvider.isLogged();
    switch (settings.name) {
      case '/':
        return MaterialPageRoute(builder: (_) => HomePage());
        break;
      case '/login':
        return MaterialPageRoute(builder: (_) => LoginPage());
        break;
      case '/register':
        return MaterialPageRoute(builder: (_) => RegisterPage());
        break;
      case '/terms':
        return MaterialPageRoute(builder: (_) => TermsPage());
        break;
      case '/home':
        return MaterialPageRoute(builder: (_) { 

          return HomePage();});
        break;
      default:
        return MaterialPageRoute(
            builder: (_) => Scaffold(
                  body: Center(
                      child: Text('No route defined for ${settings.name}')),
                ));
        break;
    }
  }
}

这个“我的尝试”给了我错误。我怎样才能做到这一点？ “在此 MyApp 小部件上方找不到正确的 ProviderProvider>。”

Answer 1

在这种情况下 context不包括提供者。所以可以通过将MaterailApp放入MultiProvider的builder方法中来实现，例如:

class MyApp extends StatelessWidget {

@override
Widget build(BuildContext context1) {

  return MultiProvider(
   providers: <SingleChildCloneableWidget>[
     ChangeNotifierProvider(builder: (_) => BottomNavigationBarProvider()),
     ChangeNotifierProvider(builder: (_) => UserProvider()),
   ],
   builder: (context2, _) =>  MaterialApp(
    initialRoute: '/',
    onGenerateRoute: Router(context2).generateRoute,
    title: 'Title',
    theme: ThemeData(
      primarySwatch: Colors.blue,
    ),
   ),
  );
 }
}

现在 UserProvider可以从 context2 访问调用 Provider.of<UserProvider>(context2)