preserve query params when navigating

pkgs/samples/tool/samples.dart

@@ -154,15 +154,15 @@ import 'package:collection/collection.dart';
 
 class Sample {
   final String category;
-  final String name;
   final String id;
   final String source;
+  final String? name;
 
   Sample({
     required this.category,
-    required this.name,
     required this.id,
     required this.source,
+    this.name,
   });
 
   bool get isDart => category == 'Dart';
@@ -180,9 +180,20 @@ class Samples {
     ${categories.map((category) => _mapForCategory(category)).join(',\n    ')},
   };
 
-  static Sample? getById(String? id) => all.firstWhereOrNull((s) => s.id == id);
+  static Sample? getById(String? id) {
+    final sample = all.firstWhereOrNull((s) => s.id == id);
+    if (sample != null) {
+      return sample;
+    }
+
+    if (_defaults.containsKey(id)) {
+      return Sample(category: id!, id: id, source: _defaults[id]!);
+    }
+
+    return null;
+  }
 
-  static String getDefault({required String type}) => _defaults[type]!;
+  static String? getDefault({required String type}) => _defaults[type];
 }
 
 ''');

pkgs/sketch_pad/lib/main.dart

@@ -2,6 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+// ignore: avoid_web_libraries_in_flutter
+import 'dart:html' as html;
+
 import 'package:dartpad_shared/services.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
@@ -37,6 +40,8 @@ const appName = 'DartPad';
 
 final GoRouter router = _createRouter();
 
+const exclusiveQueryParams = ['id', 'sample'];
+
 void main() async {
   setPathUrlStrategy();
 
@@ -70,10 +75,13 @@ GoRouter _createRouter() {
       GoRoute(
         path: '/',
         builder: (BuildContext context, GoRouterState state) {
-          final idParam = state.uri.queryParameters['id'];
-          final sampleParam = state.uri.queryParameters['sample'];
           final themeParam = state.uri.queryParameters['theme'] ?? 'dark';
           final channelParam = state.uri.queryParameters['channel'];
+          final idParam = state.uri.queryParameters['id'];
+          var sampleParam = state.uri.queryParameters['sample'];
+          if (idParam == null && sampleParam == null) {
+            sampleParam = 'dart';
+          }
 
           final bool darkMode = themeParam == 'dark';
           final colorScheme = ColorScheme.fromSwatch(
@@ -147,7 +155,6 @@ class _DartPadMainPageState extends State<DartPadMainPage> {
     appServices.performInitialLoad(
       sampleId: widget.sampleId,
       gistId: widget.gistId,
-      fallbackSnippet: Samples.getDefault(type: 'dart'),
     );
   }
 
@@ -308,7 +315,6 @@ class _DartPadMainPageState extends State<DartPadMainPage> {
                                 SizedBox(
                                   height: domHeight,
                                   child: ExecutionWidget(
-                                    // useMinHeight: mode.domIsVisible ? false : true,
                                     appServices: appServices,
                                   ),
                                 ),
@@ -576,10 +582,11 @@ class NewSnippetWidget extends StatelessWidget {
         icon: const Icon(Icons.add_circle),
         label: const Text('New'),
         onPressed: () async {
+          final router = GoRouter.of(context);
           final selection =
               await _showMenu(context, calculatePopupMenuPosition(context));
           if (selection != null) {
-            _handleSelection(appServices, selection);
+            _handleSelection(appServices, selection, router);
           }
         },
       ),
@@ -613,8 +620,18 @@ class NewSnippetWidget extends StatelessWidget {
     );
   }
 
-  void _handleSelection(AppServices appServices, bool dartSample) {
+  void _handleSelection(
+    AppServices appServices,
+    bool dartSample,
+    GoRouter router,
+  ) {
     appServices.resetTo(type: dartSample ? 'dart' : 'flutter');
+
+    final params = Map.of(Uri.parse(html.window.location.href).queryParameters);
+    params.remove('id');
+    params['sample'] = dartSample ? 'dart' : 'flutter';
+
+    router.go(Uri(path: '/', queryParameters: params).toString());
   }
 }
 
@@ -660,7 +677,7 @@ class ListSamplesWidget extends StatelessWidget {
             child: PointerInterceptor(
               child: ListTile(
                 leading: sample.isDart ? dartLogo() : flutterLogo(),
-                title: Text(sample.name),
+                title: Text(sample.name!),
               ),
             ),
           );
@@ -676,8 +693,10 @@ class ListSamplesWidget extends StatelessWidget {
   }
 
   void _handleSelection(BuildContext context, String sampleId) {
-    context.go(
-      Uri(path: '/', queryParameters: {'sample': sampleId}).toString(),
+    context.goRetainQueryParams(
+      path: '/',
+      params: {'sample': sampleId},
+      removeAny: exclusiveQueryParams,
     );
   }
 }
@@ -747,9 +766,9 @@ class SelectChannelWidget extends StatelessWidget {
     appServices.setChannel(channel);
 
     // update the url
-    // TODO: preserve id? sample? theme?
-    context.go(
-      Uri(path: '/', queryParameters: {'channel': channel.name}).toString(),
+    context.goRetainQueryParams(
+      path: '/',
+      params: {'channel': channel.name},
     );
   }
 }
@@ -909,3 +928,22 @@ class _VersionInfoWidgetState extends State<VersionInfoWidget> {
     );
   }
 }
+
+extension GoRouterExtension on BuildContext {
+  void goRetainQueryParams({
+    required String path,
+    required Map<String, String> params,
+    List<String> removeAny = const [],
+  }) {
+    final existingParams = Uri.parse(html.window.location.href).queryParameters;
+
+    final newMap = Map.of(existingParams);
+    for (final key in removeAny) {
+      newMap.remove(key);
+    }
+    newMap.addAll(params);
+
+    final uri = Uri(path: path, queryParameters: newMap);
+    go(uri.toString());
+  }
+}

pkgs/sketch_pad/lib/model.dart

@@ -146,7 +146,8 @@ class AppServices {
 
   void resetTo({String? type}) {
     type ??= 'dart';
-    final source = Samples.getDefault(type: type);
+
+    final source = Samples.getDefault(type: type)!;
 
     // reset the source
     appModel.sourceCodeController.text = source;
@@ -178,22 +179,25 @@ class AppServices {
   Future<void> performInitialLoad({
     String? sampleId,
     String? gistId,
-    required String fallbackSnippet,
   }) async {
+    final fallbackSource = Samples.getDefault(type: 'dart')!;
+
     // Delay a bit for codemirror to initialize.
     await Future<void>.delayed(const Duration(milliseconds: 1));
 
-    final sample = Samples.getById(sampleId);
-    if (sample != null) {
-      appModel.title.value = sample.name;
-      appModel.sourceCodeController.text = sample.source;
-      appModel.appReady.value = true;
-      return;
-    }
-
     if (gistId == null) {
-      appModel.sourceCodeController.text = fallbackSnippet;
+      final sample = Samples.getById(sampleId);
+
+      if (sample == null) {
+        appModel.editorStatus.showToast('Error loading sample');
+        appModel.sourceCodeController.text = fallbackSource;
+      } else {
+        appModel.title.value = sample.name ?? generateSnippetName();
+        appModel.sourceCodeController.text = sample.source;
+      }
+
       appModel.appReady.value = true;
+
       return;
     }
 
@@ -210,7 +214,7 @@ class AppServices {
       final source = gist.mainDartSource;
       if (source == null) {
         appModel.editorStatus.showToast('main.dart not found');
-        appModel.sourceCodeController.text = fallbackSnippet;
+        appModel.sourceCodeController.text = fallbackSource;
       } else {
         appModel.sourceCodeController.text = source;
       }
@@ -222,7 +226,7 @@ class AppServices {
 
       appModel.appendLineToConsole('Error loading gist: $e');
 
-      appModel.sourceCodeController.text = fallbackSnippet;
+      appModel.sourceCodeController.text = fallbackSource;
       appModel.appReady.value = true;
     } finally {
       gistLoader.dispose();