[go_router] Makes GoRouterState lookup more robust. (#6920)

fixes flutter/flutter#132824

Author: chunhtai

packages/go_router/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 14.2.1
+
+- Makes GoRouterState lookup more robust.
+
 ## 14.2.0
 
 - Added proper `redirect` handling for `ShellRoute.$route` and `StatefulShellRoute.$route` for proper redirection handling in case of code generation.

packages/go_router/lib/src/state.dart

@@ -98,7 +98,7 @@ class GoRouterState {
   ///
   /// This method cannot be called during [GoRoute.pageBuilder] or
   /// [ShellRoute.pageBuilder] since there is no [GoRouterState] to be
-  /// associated with.
+  /// associated with yet.
   ///
   /// To access GoRouterState from a widget.
   ///
@@ -116,26 +116,41 @@ class GoRouterState {
   /// }
   /// ```
   static GoRouterState of(BuildContext context) {
-    final ModalRoute<Object?>? route = ModalRoute.of(context);
-    if (route == null) {
-      throw GoError('There is no modal route above the current context.');
-    }
-    final RouteSettings settings = route.settings;
-    if (settings is! Page<Object?>) {
-      throw GoError(
-          'The parent route must be a page route to have a GoRouterState');
-    }
-    final GoRouterStateRegistryScope? scope = context
-        .dependOnInheritedWidgetOfExactType<GoRouterStateRegistryScope>();
-    if (scope == null) {
-      throw GoError(
-          'There is no GoRouterStateRegistryScope above the current context.');
+    ModalRoute<Object?>? route;
+    GoRouterStateRegistryScope? scope;
+    while (true) {
+      route = ModalRoute.of(context);
+      if (route == null) {
+        throw _noGoRouterStateError;
+      }
+      final RouteSettings settings = route.settings;
+      if (settings is Page<Object?>) {
+        scope = context
+            .dependOnInheritedWidgetOfExactType<GoRouterStateRegistryScope>();
+        if (scope == null) {
+          throw _noGoRouterStateError;
+        }
+        final GoRouterState? state = scope.notifier!
+            ._createPageRouteAssociation(
+                route.settings as Page<Object?>, route);
+        if (state != null) {
+          return state;
+        }
+      }
+      final NavigatorState? state = Navigator.maybeOf(context);
+      if (state == null) {
+        throw _noGoRouterStateError;
+      }
+      context = state.context;
     }
-    final GoRouterState state =
-        scope.notifier!._createPageRouteAssociation(settings, route);
-    return state;
   }
 
+  static GoError get _noGoRouterStateError => GoError(
+        'There is no GoRouterState above the current context. '
+        'This method should only be called under the sub tree of a '
+        'RouteBase.builder.',
+      );
+
   /// Get a location from route name and parameters.
   /// This is useful for redirecting to a named location.
   String namedLocation(
@@ -207,10 +222,12 @@ class GoRouterStateRegistry extends ChangeNotifier {
   final Map<Route<Object?>, Page<Object?>> _routePageAssociation =
       <ModalRoute<Object?>, Page<Object?>>{};
 
-  GoRouterState _createPageRouteAssociation(
+  GoRouterState? _createPageRouteAssociation(
       Page<Object?> page, ModalRoute<Object?> route) {
     assert(route.settings == page);
-    assert(registry.containsKey(page));
+    if (!registry.containsKey(page)) {
+      return null;
+    }
     final Page<Object?>? oldPage = _routePageAssociation[route];
     if (oldPage == null) {
       // This is a new association.

packages/go_router/pubspec.yaml

@@ -1,7 +1,7 @@
 name: go_router
 description: A declarative router for Flutter based on Navigation 2 supporting
   deep linking, data-driven routes and more
-version: 14.2.0
+version: 14.2.1
 repository: https://github.com/flutter/packages/tree/main/packages/go_router
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+go_router%22
 

packages/go_router/test/go_router_state_test.dart

@@ -185,6 +185,39 @@ void main() {
       expect(find.byKey(key), findsNothing);
     });
 
+    testWidgets(
+        'GoRouterState look up should be resilient when there is a nested navigator.',
+        (WidgetTester tester) async {
+      final List<GoRoute> routes = <GoRoute>[
+        GoRoute(
+          path: '/',
+          builder: (_, __) {
+            return Scaffold(
+              appBar: AppBar(),
+              body: Navigator(
+                pages: <Page<void>>[
+                  MaterialPage<void>(
+                    child: Builder(
+                      builder: (BuildContext context) {
+                        return Center(
+                          child: Text(GoRouterState.of(context).uri.toString()),
+                        );
+                      },
+                    ),
+                  ),
+                ],
+                onPopPage: (Route<Object?> route, Object? result) {
+                  throw UnimplementedError();
+                },
+              ),
+            );
+          },
+        )
+      ];
+      await createRouter(routes, tester);
+      expect(find.text('/'), findsOneWidget);
+    });
+
     testWidgets('GoRouterState topRoute accessible from StatefulShellRoute',
         (WidgetTester tester) async {
       final GlobalKey<NavigatorState> rootNavigatorKey =