From 5bc6504b235923a280f7e810422b86e8f784f3e2 Mon Sep 17 00:00:00 2001
From: Jhonathan Queiroz <jhonathanqz011@gmail.com>
Date: Tue, 24 Feb 2026 16:14:02 -0300
Subject: [PATCH 1/2] Fix patternToPath to throw when path parameter is missing

---
 packages/go_router/lib/src/path_utils.dart         |  6 +++++-
 .../fix_pattern_to_path_throws.yaml                |  3 +++
 packages/go_router/test/path_utils_test.dart       | 14 ++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 packages/go_router/pending_changelogs/fix_pattern_to_path_throws.yaml

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/pending_changelogs/fix_pattern_to_path_throws.yaml b/packages/go_router/pending_changelogs/fix_pattern_to_path_throws.yaml
new file mode 100644
index 000000000000..fd0702968c65
--- /dev/null
+++ b/packages/go_router/pending_changelogs/fix_pattern_to_path_throws.yaml
@@ -0,0 +1,3 @@
+changelog: |
+  - Fixes `patternToPath` to throw `GoException` when a path parameter is missing instead of producing URLs containing the literal "null".
+version: patch
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);

From 475c420dadaf9c9a008f6038b4136483715a089b Mon Sep 17 00:00:00 2001
From: "Jhonathan C. Queiroz" <74057391+jhonathanqz@users.noreply.github.com>
Date: Fri, 6 Mar 2026 09:18:30 -0300
Subject: [PATCH 2/2] Update packages/go_router/lib/src/path_utils.dart

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
---
 packages/go_router/lib/src/path_utils.dart | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/go_router/lib/src/path_utils.dart b/packages/go_router/lib/src/path_utils.dart
index e4e2b323651f..04082994abd0 100644
--- a/packages/go_router/lib/src/path_utils.dart
+++ b/packages/go_router/lib/src/path_utils.dart
@@ -87,7 +87,7 @@ String patternToPath(String pattern, Map<String, String> pathParameters) {
     final String name = match[1]!;
     final String? value = pathParameters[name];
     if (value == null) {
-      throw GoException('Missing path parameter: $name');
+      throw GoException('Missing path parameter: $name for pattern "$pattern"');
     }
     buffer.write(value);
     start = match.end;