migrate place_tracker to go_router (#1529)

place_tracker/lib/place.dart

@@ -42,6 +42,27 @@ class Place {
       starRating: starRating ?? this.starRating,
     );
   }
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is Place &&
+          runtimeType == other.runtimeType &&
+          id == other.id &&
+          latLng == other.latLng &&
+          name == other.name &&
+          category == other.category &&
+          description == other.description &&
+          starRating == other.starRating;
+
+  @override
+  int get hashCode =>
+      id.hashCode ^
+      latLng.hashCode ^
+      name.hashCode ^
+      category.hashCode ^
+      description.hashCode ^
+      starRating.hashCode;
 }
 
 enum PlaceCategory {

place_tracker/lib/place_details.dart

@@ -4,17 +4,17 @@
 
 import 'package:flutter/material.dart';
 import 'package:google_maps_flutter/google_maps_flutter.dart';
+import 'package:provider/provider.dart';
 
 import 'place.dart';
+import 'place_tracker_app.dart';
 import 'stub_data.dart';
 
 class PlaceDetails extends StatefulWidget {
   final Place place;
-  final ValueChanged<Place> onChanged;
 
   const PlaceDetails({
     required this.place,
-    required this.onChanged,
     super.key,
   });
 
@@ -41,7 +41,7 @@ class _PlaceDetailsState extends State<PlaceDetails> {
             child: IconButton(
               icon: const Icon(Icons.save, size: 30.0),
               onPressed: () {
-                widget.onChanged(_place);
+                _onChanged(_place);
                 Navigator.pop(context);
               },
             ),
@@ -61,7 +61,7 @@ class _PlaceDetailsState extends State<PlaceDetails> {
   void initState() {
     _place = widget.place;
     _nameController.text = _place.name;
-    _descriptionController.text = _place.description!;
+    _descriptionController.text = _place.description ?? '';
     return super.initState();
   }
 
@@ -113,12 +113,22 @@ class _PlaceDetailsState extends State<PlaceDetails> {
       ));
     });
   }
+
+  void _onChanged(Place value) {
+    // Replace the place with the modified version.
+    final newPlaces = List<Place>.from(context.read<AppState>().places);
+    final index = newPlaces.indexWhere((place) => place.id == value.id);
+    newPlaces[index] = value;
+
+    context.read<AppState>().setPlaces(newPlaces);
+  }
 }
 
 class _DescriptionTextField extends StatelessWidget {
   final TextEditingController controller;
 
   final ValueChanged<String> onChanged;
+
   const _DescriptionTextField({
     required this.controller,
     required this.onChanged,
@@ -151,6 +161,7 @@ class _Map extends StatelessWidget {
   final GoogleMapController? mapController;
   final ArgumentCallback<GoogleMapController> onMapCreated;
   final Set<Marker> markers;
+
   const _Map({
     required this.center,
     required this.mapController,
@@ -187,6 +198,7 @@ class _NameTextField extends StatelessWidget {
   final TextEditingController controller;
 
   final ValueChanged<String> onChanged;
+
   const _NameTextField({
     required this.controller,
     required this.onChanged,
@@ -304,6 +316,7 @@ class _StarBar extends StatelessWidget {
 
   final int rating;
   final ValueChanged<int> onChanged;
+
   const _StarBar({
     required this.rating,
     required this.onChanged,

place_tracker/lib/place_list.dart

@@ -3,10 +3,10 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
 import 'package:provider/provider.dart';
 
 import 'place.dart';
-import 'place_details.dart';
 import 'place_tracker_app.dart';
 
 class PlaceList extends StatefulWidget {
@@ -35,10 +35,7 @@ class _PlaceListState extends State<PlaceList> {
             shrinkWrap: true,
             children: state.places
                 .where((place) => place.category == state.selectedCategory)
-                .map((place) => _PlaceListTile(
-                      place: place,
-                      onPlaceChanged: (value) => _onPlaceChanged(value),
-                    ))
+                .map((place) => _PlaceListTile(place: place))
                 .toList(),
           ),
         ),
@@ -51,16 +48,6 @@ class _PlaceListState extends State<PlaceList> {
     Provider.of<AppState>(context, listen: false)
         .setSelectedCategory(newCategory);
   }
-
-  void _onPlaceChanged(Place value) {
-    // Replace the place with the modified version.
-    final newPlaces =
-        List<Place>.from(Provider.of<AppState>(context, listen: false).places);
-    final index = newPlaces.indexWhere((place) => place.id == value.id);
-    newPlaces[index] = value;
-
-    Provider.of<AppState>(context, listen: false).setPlaces(newPlaces);
-  }
 }
 
 class _CategoryButton extends StatelessWidget {
@@ -68,6 +55,7 @@ class _CategoryButton extends StatelessWidget {
 
   final bool selected;
   final ValueChanged<PlaceCategory> onCategoryChanged;
+
   const _CategoryButton({
     required this.category,
     required this.selected,
@@ -118,6 +106,7 @@ class _ListCategoryButtonBar extends StatelessWidget {
   final PlaceCategory selectedCategory;
 
   final ValueChanged<PlaceCategory> onCategoryChanged;
+
   const _ListCategoryButtonBar({
     required this.selectedCategory,
     required this.onCategoryChanged,
@@ -151,24 +140,14 @@ class _ListCategoryButtonBar extends StatelessWidget {
 class _PlaceListTile extends StatelessWidget {
   final Place place;
 
-  final ValueChanged<Place> onPlaceChanged;
   const _PlaceListTile({
     required this.place,
-    required this.onPlaceChanged,
   });
 
   @override
   Widget build(BuildContext context) {
     return InkWell(
-      onTap: () => Navigator.push<void>(
-        context,
-        MaterialPageRoute(builder: (context) {
-          return PlaceDetails(
-            place: place,
-            onChanged: (value) => onPlaceChanged(value),
-          );
-        }),
-      ),
+      onTap: () => context.go('/place/${place.id}'),
       child: Container(
         padding: const EdgeInsets.only(top: 16.0),
         child: Column(

place_tracker/lib/place_map.dart

@@ -5,13 +5,14 @@
 import 'dart:async';
 import 'dart:math';
 
+import 'package:collection/collection.dart';
 import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
 import 'package:google_maps_flutter/google_maps_flutter.dart';
 import 'package:provider/provider.dart';
 import 'package:uuid/uuid.dart';
 
 import 'place.dart';
-import 'place_details.dart';
 import 'place_tracker_app.dart';
 
 class MapConfiguration {
@@ -78,10 +79,21 @@ class _PlaceMapState extends State<PlaceMap> {
   MapConfiguration? _configuration;
 
   @override
-  Widget build(BuildContext context) {
-    _maybeUpdateMapConfiguration();
-    var state = Provider.of<AppState>(context);
+  void initState() {
+    super.initState();
+    context.read<AppState>().addListener(_watchMapConfigurationChanges);
+  }
 
+  @override
+  void dispose() {
+    context.read<AppState>().removeListener(_watchMapConfigurationChanges);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    _watchMapConfigurationChanges();
+    var state = Provider.of<AppState>(context);
     return Builder(builder: (context) {
       // We need this additional builder here so that we can pass its context to
       // _AddPlaceButtonBar's onSavePressed callback. This callback shows a
@@ -189,7 +201,7 @@ class _PlaceMapState extends State<PlaceMap> {
           infoWindowParam: InfoWindow(
             title: 'New Place',
             snippet: null,
-            onTap: () => _pushPlaceDetailsScreen(newPlace),
+            onTap: () => context.go('/place/${newPlace.id}'),
           ),
           draggableParam: false,
         );
@@ -212,7 +224,7 @@ class _PlaceMapState extends State<PlaceMap> {
           action: SnackBarAction(
             label: 'Edit',
             onPressed: () async {
-              _pushPlaceDetailsScreen(newPlace);
+              context.go('/place/${newPlace.id}');
             },
           ),
         ),
@@ -221,14 +233,6 @@ class _PlaceMapState extends State<PlaceMap> {
       // Add the new place to the places stored in appState.
       final newPlaces = List<Place>.from(appState.places)..add(newPlace);
 
-      // Manually update our map configuration here since our map is already
-      // updated with the new marker. Otherwise, the map would be reconfigured
-      // in the main build method due to a modified AppState.
-      _configuration = MapConfiguration(
-        places: newPlaces,
-        selectedCategory: appState.selectedCategory,
-      );
-
       appState.setPlaces(newPlaces);
     }
   }
@@ -240,7 +244,7 @@ class _PlaceMapState extends State<PlaceMap> {
       infoWindow: InfoWindow(
         title: place.name,
         snippet: '${place.starRating} Star Rating',
-        onTap: () => _pushPlaceDetailsScreen(place),
+        onTap: () => context.go('/place/${place.id}'),
       ),
       icon: await _getPlaceMarkerIcon(context, place.category),
       visible: place.category ==
@@ -250,11 +254,10 @@ class _PlaceMapState extends State<PlaceMap> {
     return marker;
   }
 
-  Future<void> _maybeUpdateMapConfiguration() async {
-    _configuration ??=
-        MapConfiguration.of(Provider.of<AppState>(context, listen: false));
-    final newConfiguration =
-        MapConfiguration.of(Provider.of<AppState>(context, listen: false));
+  Future<void> _watchMapConfigurationChanges() async {
+    final appState = context.read<AppState>();
+    _configuration ??= MapConfiguration.of(appState);
+    final newConfiguration = MapConfiguration.of(appState);
 
     // Since we manually update [_configuration] when place or selectedCategory
     // changes come from the [place_map], we should only enter this if statement
@@ -270,9 +273,14 @@ class _PlaceMapState extends State<PlaceMap> {
       } else {
         // At this point, we know the places have been updated from the list
         // view. We need to reconfigure the map to respect the updates.
-        newConfiguration.places
-            .where((p) => !_configuration!.places.contains(p))
-            .map((value) => _updateExistingPlaceMarker(place: value));
+        for (final place in newConfiguration.places) {
+          final oldPlace =
+              _configuration!.places.firstWhereOrNull((p) => p.id == place.id);
+          if (oldPlace == null || oldPlace != place) {
+            // New place or updated place.
+            _updateExistingPlaceMarker(place: place);
+          }
+        }
 
         await _zoomToFitPlaces(
           _getPlacesForCategory(
@@ -299,27 +307,6 @@ class _PlaceMapState extends State<PlaceMap> {
     });
   }
 
-  void _onPlaceChanged(Place value) {
-    // Replace the place with the modified version.
-    final newPlaces =
-        List<Place>.from(Provider.of<AppState>(context, listen: false).places);
-    final index = newPlaces.indexWhere((place) => place.id == value.id);
-    newPlaces[index] = value;
-
-    _updateExistingPlaceMarker(place: value);
-
-    // Manually update our map configuration here since our map is already
-    // updated with the new marker. Otherwise, the map would be reconfigured
-    // in the main build method due to a modified AppState.
-    _configuration = MapConfiguration(
-      places: newPlaces,
-      selectedCategory:
-          Provider.of<AppState>(context, listen: false).selectedCategory,
-    );
-
-    Provider.of<AppState>(context, listen: false).setPlaces(newPlaces);
-  }
-
   void _onToggleMapTypePressed() {
     final nextType =
         MapType.values[(_currentMapType.index + 1) % MapType.values.length];
@@ -329,18 +316,6 @@ class _PlaceMapState extends State<PlaceMap> {
     });
   }
 
-  void _pushPlaceDetailsScreen(Place place) {
-    Navigator.push<void>(
-      context,
-      MaterialPageRoute(builder: (context) {
-        return PlaceDetails(
-          place: place,
-          onChanged: (value) => _onPlaceChanged(value),
-        );
-      }),
-    );
-  }
-
   Future<void> _showPlacesForSelectedCategory(PlaceCategory category) async {
     setState(() {
       for (var marker in List.of(_markedPlaces.keys)) {
@@ -412,15 +387,17 @@ class _PlaceMapState extends State<PlaceMap> {
       maxLong = max(maxLong, place.longitude);
     }
 
-    await controller.animateCamera(
-      CameraUpdate.newLatLngBounds(
-        LatLngBounds(
-          southwest: LatLng(minLat, minLong),
-          northeast: LatLng(maxLat, maxLong),
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      controller.animateCamera(
+        CameraUpdate.newLatLngBounds(
+          LatLngBounds(
+            southwest: LatLng(minLat, minLong),
+            northeast: LatLng(maxLat, maxLong),
+          ),
+          48.0,
         ),
-        48.0,
-      ),
-    );
+      );
+    });
   }
 
   static Future<BitmapDescriptor> _getPlaceMarkerIcon(

place_tracker/lib/place_tracker_app.dart

@@ -3,10 +3,12 @@
 // found in the LICENSE file.
 
 import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
 import 'package:google_maps_flutter/google_maps_flutter.dart';
 import 'package:provider/provider.dart';
 
 import 'place.dart';
+import 'place_details.dart';
 import 'place_list.dart';
 import 'place_map.dart';
 import 'stub_data.dart';
@@ -21,8 +23,26 @@ class PlaceTrackerApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return const MaterialApp(
-      home: _PlaceTrackerHomePage(),
+    return MaterialApp.router(
+      routerConfig: GoRouter(routes: [
+        GoRoute(
+          path: '/',
+          builder: (context, state) => const _PlaceTrackerHomePage(),
+          routes: [
+            GoRoute(
+              path: 'place/:id',
+              builder: (context, state) {
+                final id = state.params['id']!;
+                final place = context
+                    .read<AppState>()
+                    .places
+                    .singleWhere((place) => place.id == id);
+                return PlaceDetails(place: place);
+              },
+            ),
+          ],
+        ),
+      ]),
     );
   }
 }

place_tracker/pubspec.yaml

@@ -15,6 +15,8 @@ dependencies:
   google_maps_flutter_web: ">=0.3.0+1 <0.5.0"
   provider: ^6.0.2
   uuid: ^3.0.4
+  go_router: ^5.2.4
+  collection: ^1.16.0
 
 dev_dependencies:
   flutter_test: