This skill defines how to correctly use the provider package in Flutter applications.
| Provider | \nUse for | \n
|---|---|
Provider | \nExposing any immutable value | \n
ChangeNotifierProvider | \nMutable state with ChangeNotifier | \n
FutureProvider | \nExposing a Future result | \n
StreamProvider | \nExposing a Stream | \n
ProxyProvider / ChangeNotifierProxyProvider | \nObjects that depend on other providers | \n
MultiProvider(\n providers: [\n Provider<Something>(create: (_) => Something()),\n ChangeNotifierProvider(create: (_) => MyNotifier()),\n FutureProvider<String>(create: (_) => fetchData(), initialData: ''),\n ],\n child: MyApp(),\n)\nMultiProvider to group multiple providers and avoid deeply nested trees.ChangeNotifierProvider automatically disposes the model when it is no longer needed.ProxyProvider instead.StackOverflowError.Always specify the generic type for type safety:
\n// Listen and rebuild on change — only valid inside build() or a Provider's update method\nfinal count = context.watch<MyModel>().count;\n\n// Access without listening — use in callbacks, not inside build()\ncontext.read<MyModel>().increment();\n\n// Listen to only part of the state\nfinal count = context.select<MyModel, int>((m) => m.count);\nUse Consumer<T> or Selector<T, R> widgets when you need fine-grained rebuilds and cannot access a descendant BuildContext:
Consumer<MyModel>(\n builder: (context, model, child) => Text('${model.count}'),\n child: const ExpensiveWidget(), // rebuilt only once\n)\n\nSelector<MyModel, int>(\n selector: (_, model) => model.count,\n builder: (_, count, __) => Text('$count'),\n)\nUse ProxyProvider or ChangeNotifierProxyProvider for objects that depend on other providers or values that can change:
MultiProvider(\n providers: [\n Provider<Auth>(create: (_) => Auth()),\n ProxyProvider<Auth, Api>(\n update: (_, auth, __) => Api(auth.token),\n ),\n ],\n)\ninitState or constructors — use them in build, callbacks, or lifecycle methods where the widget is fully mounted.ChangeNotifier; use Provider.value() with a StatefulWidget if needed.Implement toString or DiagnosticableTreeMixin to improve how your objects appear in Flutter DevTools:
class MyModel with DiagnosticableTreeMixin {\n final int count;\n MyModel(this.count);\n\n @override\n String toString() => 'MyModel(count: $count)';\n}\nValueListenableProvider is deprecated. Use Provider with ValueListenableBuilder instead:
ValueListenableBuilder<int>(\n valueListenable: myValueListenable,\n builder: (context, value, _) {\n return Provider<int>.value(\n value: value,\n child: MyApp(),\n );\n },\n)\n