go_router and flutter_bloc: Unhandled Exception: No GoRouter found in context - flutter

Question

I have wrapped the MaterialApp with a BlocProvider / BlocListener
I get an error
"Unhandled Exception: 'package:go_router/src/router.dart': Failed assertion: line 280 pos 12: 'inherited != null': No GoRouter found in context" from the Listener callback
Widget build(BuildContext context) {
return BlocProvider<AuthenticationBloc>(
create: (context) => AuthenticationBloc()..add(AppStarted()),
child: BlocListener<AuthenticationBloc, AuthenticationState>(
listener: (context, state) {
if (state is AuthenticationUnauthenticated) {
context.goNamed(LoginPage.routeName);
}
if (state is AuthenticationAuthenticated) {
context.goNamed(NavigationBarContainer.routeName);
}
},
child: MaterialApp.router(
title: 'Flutter Demo',
routeInformationProvider: _router.routeInformationProvider,
routeInformationParser: _router.routeInformationParser,
routerDelegate: _router.routerDelegate,
theme: ThemeData(
primarySwatch: Colors.blue,
)),
),
);
}

Answer 1

This is happening because you are using context of go_router before it is initialized !!
Widget build(BuildContext context) {
return BlocProvider<AuthenticationBloc>(
create: (context) => AuthenticationBloc()..add(AppStarted()),
child: BlocListener<AuthenticationBloc, AuthenticationState>(
listener: (context, state) {
if (state is AuthenticationUnauthenticated) {
context.goNamed(LoginPage.routeName); // 👈 Go router is not initilaized yet
}
if (state is AuthenticationAuthenticated) {
context.goNamed(NavigationBarContainer.routeName); // 👈 Go router is not initilaized yet
}
},
child: MaterialApp.router(
routeInformationProvider: _router.routeInformationProvider,
routeInformationParser: _router.routeInformationParser,
routerDelegate: _router.routerDelegate, // 👈 Your router is initialized here
),
);
}
Make changes to :
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return MultiBlocProvider(
providers: [
BlocProvider<AuthenticationBloc>(
create: (context) => AuthenticationBloc()..add(AppStarted()), 👈 Specify only the BlocProvider here
),
],
child: MaterialApp(
theme: customTheme(context),
debugShowCheckedModeBanner: false,
routeInformationProvider: _router.routeInformationProvider,
routeInformationParser: _router.routeInformationParser,
routerConfig: router,
}
And then try to navigate inside the routerlike:
final GoRouter router = GoRouter(routes: [
GoRoute(
path: "/",
builder: (context, state) {
return BlocBuilder<AuthCubit, AuthState>(
buildWhen: (oldState, newState) {
return oldState is AuthInitialState;
},
builder: (context, state) {
if (state is AuthenticationUnauthenticated) {
// return const LoginPage(); // alternative way
context.goNamed(LoginPage.routeName); 👈 Use conditional routing using context here
} else if (state is NavigationBarContainer.routeName) {
// return SignIn(); // alternative way
context.goNamed(NavigationBarContainer.routeName); 👈 Use conditional routing using context here
} else {
return const Scaffold();
}
},
);
}),

Answer 2

You are attempting to navigate with context from higher up in the widget tree than go_router gets inserted.
I don't know where your GoRouter() routerConfig is, and where it is called from when you use a RouterDelegate, (maybe you don't need to use a delegate?) but you need to call your GoRouter configuration directly, and navigate from that.
So you need to change:
context.goNamed(LoginPage.routeName)
to
routerConfig.goNamed(LoginPage.routeName)
For me, you can see I pass the routerConfig to MaterialApp.router, and I also navigate directly from that, with routerConfig.go(HOME), from above the MaterialApp:
ref.watch(authStatusServiceProvider).whenData((authStatus) {
switch (authStatus) {
case AuthenticationStatusEnum.authenticated:
routerConfig.go(HOME);
break;
case AuthenticationStatusEnum.unauthenticated:
routerConfig.go(LOGGED_OUT_HOME);
break;
default:
routerConfig.go(LOGGED_OUT_HOME);
break;
}
});
return MaterialApp.router(
theme: lightTheme,
debugShowCheckedModeBanner: false,
darkTheme: darkTheme,
routerConfig: routerConfig,
);
}
All credit goes to darshankawar on Github.