Flutter read riverpod provider in GoRoute builder - flutter

Question

My Flutter project is migrating to go_router and I have trouble understanding how to access riverpod providers in either a GoRoute's build method or redirect method, as I need to access the user's data to control the navigation.
I have a top-level redirect that checks if a user is logged in and sends them to a LoginPage if not. All users can access so-called activities in my app, but only admins can edit them. Whether a user is an admin is stored in a riverpod userDataProvider, which always contains a user if the user is logged in. Now if a user attempts to enter the route /:activityId?edit=true, I want to check whether they are allowed to by accessing the userDataProvider. However, I do not see what the clean way of accessing this provider is.
I found somewhere (can't find the thread anymore), that one way is to use ProviderScope.containerOf(context).read(userDataProvider), but I have never seen this before and it seems a bit exotic to me. Is this the way to go?
My GoRoute looks something like this:
GoRoute(
path: RouteName.event.relPath,
builder: (context, state) {
final String? id = state.params['id'];
final bool edit = state.queryParams['edit'] == 'true';
if (state.extra == null) {
// TODO: Fetch data
}
final data = state.extra! as Pair<ActivityData, CachedNetworkImage?>;
if (edit) {
return CreateActivity(
isEdit: true,
data: data.a,
banner: data.b,
);
}
return ActivityPage(
id: id!,
data: data.a,
banner: data.b,
);
},
redirect: (context, state) {
final bool edit = state.queryParams['edit'] == 'true';
if (edit) {
// IMPORTANT: How to access the ref here?
final bool isAdmin =
ref.read(userDataProvider).currentUser.customClaims.admin;
if (isAdmin) {
return state.location; // Includes the queryParam edit
} else {
return state.subloc; // Does not include queryParam
}
} else {
return state.path;
}
},
),

Answer 1

In my current application, I used something similar approach like this :
Provider registration part (providers.dart) :
final routerProvider = Provider<GoRouter>((ref) {
final router = RouterNotifier(ref);
return GoRouter(
debugLogDiagnostics: true,
refreshListenable: router,
redirect: (context, state) {
router._redirectLogic(state);
return null;
},
routes: ref.read(routesProvider));
});
class RouterNotifier extends ChangeNotifier {
final Ref _ref;
RouterNotifier(this._ref) {
_ref.listen<AuthState>(authNotifierProvider, (_, __) => notifyListeners());
}
String? _redirectLogic(GoRouterState state) {
final loginState = _ref.watch(authNotifierProvider);
final areWeLoggingIn = state.location == '/login';
if (loginState.state != AuthenticationState.authenticated) {
return areWeLoggingIn ? null : '/login';
}
if (areWeLoggingIn) return '/welcome';
return null;
}
}
Main app building as router (app.dart):
class App extends ConsumerWidget {
const App({Key? key}) : super(key: key);
// This widget is the root of your application.
#override
Widget build(BuildContext context, WidgetRef ref) {
final GoRouter router = ref.watch(routerProvider);
return MaterialApp.router(
routeInformationProvider: router.routeInformationProvider,
routeInformationParser: router.routeInformationParser,
routerDelegate: router.routerDelegate,
debugShowCheckedModeBanner: false,
title: 'Flutter Auth',
}
}
}
And as entrypoint (main.dart):
Future<void> main() async {
F.appFlavor = Flavor.dev;
WidgetsFlutterBinding.ensureInitialized();
await setup();
runApp(ProviderScope(
observers: [
Observers(),
],
child: const App(),
));
}