[go_router] add initial json support flutter#110781 (flutter#9404)

Add initial json support for use in go_router_builder
Adds annotation that enable custom string encoder/decoder, its enable conversion for base64

This allow custom type conversion for parameters, like mentionated in [flutter#117261](flutter#117261) and [flutter#110781](flutter#110781)

this PR must made before [flutter#117261](flutter/packages#8665)

## Pre-Review Checklist

[^1]: Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling.

Author: NearTox

packages/go_router/CHANGELOG.md

@@ -1,3 +1,6 @@
+## 16.1.0
+- Adds annotation for go_router_builder that enable custom string encoder/decoder [#110781](https://github.com/flutter/flutter/issues/110781). **Requires go_router_builder >= 3.1.0**.
+
 ## 16.0.0
 
 - **BREAKING CHANGE**
@@ -35,7 +38,7 @@
 ## 14.8.1
 
 - Secured canPop method for the lack of matches in routerDelegate's configuration.
- 
+
 ## 14.8.0
 
 - Adds `preload` parameter to `StatefulShellBranchData.$branch`.

packages/go_router/lib/go_router.dart

@@ -11,6 +11,7 @@ export 'src/configuration.dart';
 export 'src/delegate.dart';
 export 'src/information_provider.dart';
 export 'src/match.dart' hide RouteMatchListCodec;
+export 'src/misc/custom_parameter.dart';
 export 'src/misc/errors.dart';
 export 'src/misc/extensions.dart';
 export 'src/misc/inherited_router.dart';

packages/go_router/lib/src/misc/custom_parameter.dart

@@ -0,0 +1,42 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:meta/meta_meta.dart' show Target, TargetKind;
+
+/// annotation to define a custom parameter decoder/encoder
+/// this is useful when the is encoded/decoded in a non-standard way like base64Url
+/// this must be used as an annotation on a field
+/// ```dart
+/// String fromBase64(String value) {
+///   return const Utf8Decoder()
+///     .convert(base64Url.decode(base64Url.normalize(value)));
+/// }
+/// String toBase64(String value) {
+///   return base64Url.encode(const Utf8Encoder().convert(value));
+/// }
+/// @TypedGoRoute<JsonRoute>(path: 'json')
+/// class JsonRoute extends GoRouteData with _$EncodedRoute {
+///   @CustomParameterCodec(
+///     encode: toBase64,
+///     decode: fromBase64,
+///   )
+///   final String data;
+///   JsonRoute(this.data);
+/// }
+/// ```
+@Target(<TargetKind>{TargetKind.field})
+final class CustomParameterCodec {
+  /// create a custom parameter codec
+  ///
+  const CustomParameterCodec({
+    required this.encode,
+    required this.decode,
+  });
+
+  /// custom function to encode the field
+  final String Function(String field) encode;
+
+  /// custom function to decode the field
+  final String Function(String field) decode;
+}

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: 16.0.0
+version: 16.1.0
 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/route_data_test.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:convert';
 
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -226,6 +227,14 @@ final List<GoRoute> _routes = <GoRoute>[
   _goRouteDataRedirect,
 ];
 
+String fromBase64(String value) {
+  return const Utf8Decoder().convert(base64.decode(value));
+}
+
+String toBase64(String value) {
+  return base64.encode(const Utf8Encoder().convert(value));
+}
+
 void main() {
   group('GoRouteData', () {
     testWidgets(
@@ -633,4 +642,14 @@ void main() {
           ),
     );
   });
+
+  test('CustomParameterCodec with required parameters', () {
+    const CustomParameterCodec customParameterCodec = CustomParameterCodec(
+      encode: toBase64,
+      decode: fromBase64,
+    );
+
+    expect(customParameterCodec.encode, toBase64);
+    expect(customParameterCodec.decode, fromBase64);
+  });
 }