From 997e269e9078db36be0691e0cf4a7fa9b4bb4354 Mon Sep 17 00:00:00 2001
From: Jhonathan Queiroz <jhonathanqz011@gmail.com>
Date: Tue, 24 Feb 2026 16:14:02 -0300
Subject: [PATCH] Fix patternToPath to throw when path parameter is missing

---
 packages/go_router/CHANGELOG.md              |  4 ++++
 packages/go_router/lib/src/path_utils.dart   |  6 +++++-
 packages/go_router/pubspec.yaml              |  2 +-
 packages/go_router/test/path_utils_test.dart | 14 ++++++++++++++
 4 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/packages/go_router/CHANGELOG.md b/packages/go_router/CHANGELOG.md
index f1d95f90c9fc..150e543ee5e9 100644
--- a/packages/go_router/CHANGELOG.md
+++ b/packages/go_router/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 17.1.1
+
+- Fixes `patternToPath` to throw `GoException` when a path parameter is missing instead of producing URLs containing the literal "null".
+
 ## 17.1.0
 
 - Adds `TypedQueryParameter` annotation to override parameter names in `TypedGoRoute` constructors.
diff --git a/packages/go_router/lib/src/path_utils.dart b/packages/go_router/lib/src/path_utils.dart
index ed1ce7cc2015..e4e2b323651f 100644
--- a/packages/go_router/lib/src/path_utils.dart
+++ b/packages/go_router/lib/src/path_utils.dart
@@ -85,7 +85,11 @@ String patternToPath(String pattern, Map<String, String> pathParameters) {
       buffer.write(pattern.substring(start, match.start));
     }
     final String name = match[1]!;
-    buffer.write(pathParameters[name]);
+    final String? value = pathParameters[name];
+    if (value == null) {
+      throw GoException('Missing path parameter: $name');
+    }
+    buffer.write(value);
     start = match.end;
   }
 
diff --git a/packages/go_router/pubspec.yaml b/packages/go_router/pubspec.yaml
index 55ad56b1058c..91402a841cb7 100644
--- a/packages/go_router/pubspec.yaml
+++ b/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: 17.1.0
+version: 17.1.1
 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
 
diff --git a/packages/go_router/test/path_utils_test.dart b/packages/go_router/test/path_utils_test.dart
index 6dbf91102676..3bbbb13a632a 100644
--- a/packages/go_router/test/path_utils_test.dart
+++ b/packages/go_router/test/path_utils_test.dart
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'package:flutter_test/flutter_test.dart';
+import 'package:go_router/go_router.dart' show GoException;
 import 'package:go_router/src/path_utils.dart';
 
 void main() {
@@ -95,6 +96,19 @@ void main() {
     expect(url, restoredUrl);
   });
 
+  test('patternToPath throws when path parameter is missing', () {
+    const pattern = '/user/:id/book/:bookId';
+    final incompleteParams = <String, String>{'id': '123'};
+    expect(
+      () => patternToPath(pattern, incompleteParams),
+      throwsA(isA<GoException>().having(
+        (GoException e) => e.message,
+        'message',
+        contains('Missing path parameter: bookId'),
+      )),
+    );
+  });
+
   test('concatenatePaths', () {
     void verify(String pathA, String pathB, String expected) {
       final String result = concatenatePaths(pathA, pathB);