setup provider

compass_app/app/lib/features/results/presentation/results_screen.dart

@@ -1,23 +1,18 @@
 import 'package:compass_app/features/results/presentation/results_viewmodel.dart';
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
 class ResultsScreen extends StatelessWidget {
-  ResultsScreen({
+  const ResultsScreen({
     super.key,
-    required this.resultsViewModel,
-  }) {
-    resultsViewModel.search();
-  }
-
-  final ResultsViewModel resultsViewModel;
+  });
 
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      body: ListenableBuilder(
-        listenable: resultsViewModel,
-        builder: (BuildContext context, Widget? child) {
-          if (resultsViewModel.loading) {
+      body: Consumer<ResultsViewModel>(
+        builder: (context, viewModel, child) {
+          if (viewModel.loading) {
             return const CircularProgressIndicator();
           }
           return const Placeholder();

compass_app/app/lib/features/results/presentation/results_viewmodel.dart

@@ -7,7 +7,10 @@ import 'package:flutter/cupertino.dart';
 class ResultsViewModel extends ChangeNotifier {
   ResultsViewModel({
     required SearchDestinationUsecase searchDestinationUsecase,
-  }) : _searchDestinationUsecase = searchDestinationUsecase;
+  }) : _searchDestinationUsecase = searchDestinationUsecase {
+    // Preload a search result
+    search();
+  }
 
   final SearchDestinationUsecase _searchDestinationUsecase;
 

compass_app/app/lib/main.dart

@@ -1,12 +1,32 @@
 import 'package:compass_app/features/results/business/usecases/search_destination_usecase.dart';
 import 'package:compass_app/features/results/data/destination_repository.dart';
-import 'package:compass_app/features/results/presentation/results_screen.dart';
 import 'package:compass_app/features/results/presentation/results_viewmodel.dart';
 import 'package:compass_app/routing/router.dart';
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 
 void main() {
-  runApp(const MainApp());
+  // Configure dependencies
+  // These dependencies don't need to be in the widget tree (yet?)
+  final repository = DestinationRepository();
+  final searchDestinationUsecase =
+      SearchDestinationUsecase(repository: repository);
+
+  runApp(
+    MultiProvider(
+      providers: [
+        // ViewModels are injected into Views using Provider
+        ChangeNotifierProvider(
+          create: (_) => ResultsViewModel(
+            searchDestinationUsecase: searchDestinationUsecase,
+          ),
+          // create this ViewModel only when needed
+          lazy: true,
+        ),
+      ],
+      child: const MainApp(),
+    ),
+  );
 }
 
 class MainApp extends StatelessWidget {

compass_app/app/lib/routing/router.dart

@@ -1,22 +1,14 @@
-import 'package:compass_app/features/results/business/usecases/search_destination_usecase.dart';
-import 'package:compass_app/features/results/data/destination_repository.dart';
 import 'package:compass_app/features/results/presentation/results_screen.dart';
-import 'package:compass_app/features/results/presentation/results_viewmodel.dart';
 import 'package:go_router/go_router.dart';
 
 final router = GoRouter(
   initialLocation: '/results',
   routes: [
     GoRoute(
-        path: '/results',
-        builder: (context, state) {
-          return ResultsScreen(
-            resultsViewModel: ResultsViewModel(
-              searchDestinationUsecase: SearchDestinationUsecase(
-                repository: DestinationRepository(),
-              ),
-            ),
-          );
-        })
+      path: '/results',
+      builder: (context, state) {
+        return const ResultsScreen();
+      },
+    ),
   ],
 );

compass_app/app/pubspec.yaml

@@ -10,6 +10,7 @@ dependencies:
   flutter:
     sdk: flutter
   go_router: ^14.2.0
+  provider: ^6.1.2
 
 dev_dependencies:
   flutter_test: