A Reactive Caching and Data-binding Framework

Majid Hajian

mhadaily

Agenda

Riverpod vs Provider

Providers

Best practices

Testing

ME.dart

import 'package:flutter/material.dart';
MaterialApp(
   ThemeData(
        name: "Majid Hajian",
        location: "Oslo, Norway",
        description: '''
                Google Developer Expert
        	Passionate Software engineer, 
	        Community Leader, Author and international Speaker
         ''',
        main: "Head of DevRel at Invertase.io",
        homepage: "https://www.majidhajian.com",
        socials: {
          twitter: "https://www.twitter.com/mhadaily",
          github: "https://www.github.com/mhadaily"
        },
        author: {
          Pluralsight: "www.pluralsight.com/authors/majid-hajian",
          Apress: "Progressive Web App with Angular, Book",
          PacktPub: "PWA development",
          Udemy: "PWA development",
        }
        founder: "Softiware As (www.Softiware.com)"
        devDependencies: {
          tea: "Ginger", 
          mac: "10.14+",
        },
        community: {
          MobileEraConference: "Orginizer",
          FlutterVikings: "Orginizer", 
          FlutterDartOslo: "Orginizer",
          GDGOslo: "Co-Orginizer",
          DevFestNorway: "Orginizer",
          ...more
        }));

mhadaily

Find me on the internet by

Head of DevRel at Invertase

What it means for Provider

Prefer using Riverpod over Provider*
Provider won't receive new features
Will still receive bug fixes and be updated to support latest language features

* Said by the author (Remi)

mhadaily

What it means for

The API is stable and production-ready
More features are on the way
The focus will shift to developer tooling and documentation
Riverpod is officially Provider "2.0"

mhadaily

Providers

An object that encapsulates a piece of state and allows listening to that state.

mhadaily

1- Allows easily accessing that state in multiple locations

Why use providers?

2- Simplifies combining this state with others

3- Enables performance optimizations

4- Increases the testability of your application

5- Allows easy integration with advanced features

mhadaily

1- Provider

2- StateProvider

3- StateNotifierProvider

4- ChangeNotifierProvider

5- StreamProvider

Providers variants

5- FutureProvider

mhadaily

Providers variants

Provider Type	Provider Create Function	Example Use Case
Provider	Returns any type	A service class / computed property (filtered list)
StateProvider	Returns any type	A filter condition / simple state object
FutureProvider	Returns a Future of any type	A result from an API call
StreamProvider	Returns a Stream of any type	A stream of results from an API
StateNotifierProvider	Returns a subclass of StateNotifier	A complex state object that is immutable except through an interface
ChangeNotifierProvider	Returns a subclass of ChangeNotifier	A complex state object that requires mutability

mhadaily

# pubspec.yaml 


dependencies:
  flutter:
    sdk: flutter
  flutter_riverpod: ^2.0.2

mhadaily

// main.dart

void main() {
  runApp(
    /// A widget that stores 
    /// the state of providers.
    const ProviderScope(
      child: MyApp(),
    ),
  );
}

mhadaily

final myCompany = Provider<String>((ref) => "Invertase");

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(
        child: Text('Norway'),
      ),
    );
  }
}

mhadaily

final myCompany = Provider<String>((ref) => "Invertase");
class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Consumer(
          builder: (context, WidgetRef ref, child) {
            final country = ref.watch(myCountry);
            return Text(country);
          },
        ),
      ),
    );
  }
}

mhadaily

final myCompany = Provider<String>((ref) => "Invertase");
class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Consumer(
          builder: (context, WidgetRef ref, child) {
            final country = ref.watch(myCountry);
            return Text(country);
          },
        ),
      ),
    );
  }
}

mhadaily

final myCountry = Provider<String>((ref) => "Invertase");


class MyHomePage extends ConsumerWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final country = ref.watch(myCountry);
    return Scaffold(
      body: Text(country),
    );
  }
}

mhadaily

StateProvider

an enum, such as a filter type
a String, typically the raw content of a text field
a boolean, for checkboxes
a number, for pagination or age form fields

You should not use StateProvider if:

your state needs validation logic
your state is a complex object (such as a custom class, a list/map, ...)
the logic for modifying your state is more advanced than a simple count++.

mhadaily

// An enum representing the filter type
enum ProductSortType {
  name,
  price,
}

class Product {
  Product({required this.name, required this.price});

  final String name;
  final double price;
}

final _products = [
  Product(name: 'iPhone', price: 999),
  Product(name: 'cookie', price: 2),
  Product(name: 'ps5', price: 500),
];

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);
//... 
 	appBar: AppBar(
        actions: [
          DropdownButton<ProductSortType>(
            value: ref.watch(productSortTypeProvider),
            onChanged: (value) {
              ref.read(productSortTypeProvider.notifier).state = value!;
            },
            items: const [
              DropdownMenuItem(
                value: ProductSortType.name,
                child: Icon(Icons.sort_by_alpha),
              ),
              DropdownMenuItem(
                value: ProductSortType.price,
                child: Icon(Icons.sort),
              ),
            ],
          ),
        ],
      )
//...

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);
//... 
 	appBar: AppBar(
        actions: [
          DropdownButton<ProductSortType>(
            value: ref.watch(productSortTypeProvider),
            onChanged: (value) {
              ref.read(productSortTypeProvider.notifier).state = value!;
            },
            items: const [
              DropdownMenuItem(
                value: ProductSortType.name,
                child: Icon(Icons.sort_by_alpha),
              ),
              DropdownMenuItem(
                value: ProductSortType.price,
                child: Icon(Icons.sort),
              ),
            ],
          ),
        ],
      )
//...

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);
//... 
 	appBar: AppBar(
        actions: [
          DropdownButton<ProductSortType>(
            value: ref.watch(productSortTypeProvider),
            onChanged: (value) {
              ref.read(productSortTypeProvider.notifier).state = value!;
            },
            items: const [
              DropdownMenuItem(
                value: ProductSortType.name,
                child: Icon(Icons.sort_by_alpha),
              ),
              DropdownMenuItem(
                value: ProductSortType.price,
                child: Icon(Icons.sort),
              ),
            ],
          ),
        ],
      )
//...

mhadaily

The `watch` method should not be called asynchronously, like inside an `onPressed` of an ElevatedButton. Nor should it be used inside `initState` and other State life-cycles.

In those cases, consider using `ref.read` instead.

mhadaily

final productsProvider = Provider<List<Product>>((ref) {
  return _products;
});





final productsProvider = Provider<List<Product>>((ref) {
  final sortType = ref.watch(productSortTypeProvider);
  switch (sortType) {
    case ProductSortType.name:
      return _products.sorted((a, b) => a.name.compareTo(b.name));
    case ProductSortType.price:
      return _products.sorted((a, b) => a.price.compareTo(b.price));
  }
});

mhadaily

StateNotifierProvider

is a provider that is used to listen to and expose a StateNotifier (from the package state_notifier, which Riverpod re-exports).
exposing an immutable state which can change over time after reacting to custom events.
centralizing the logic for modifying some state (aka "business logic") in a single place, improving maintainability over time.

mhadaily

@immutable
class Task {
  const Task({
    required this.id,
    required this.completed,
  });
  final String id;
  final bool completed;

  Task copyWith({String? id, bool? completed}) {
    return Task(
      id: id ?? this.id,
      completed: completed ?? this.completed,
    );
  }
}

mhadaily

class TasksNotifier extends StateNotifier<List<Task>> {
  TasksNotifier()
      : super(
          const [
            Task(completed: false, id: '1'),
            Task(completed: true, id: '2')
          ],
        );

  void toggle(String taskId) {
    // state in StateNotifier is immutable
    state = [
      for (final task in state)
        if (task.id == taskId)
          task.copyWith(completed: !todo.completed)
        else
          task,
    ];
  }
}

mhadaily

final tasksNotifierProvider = StateNotifierProvider<TasksNotifier, List<Task>>((ref) {
  return TasksNotifier();
});
class MyHomePage extends ConsumerWidget {
  const MyHomePage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final List<Task> tasks = ref.watch(tasksNotifierProvider);
    return Scaffold(
      body: ListView(
        children: [
          for (final task in tasks)
            CheckboxListTile(
              value: task.completed,
              onChanged: (value) {
                ref.read(tasksNotifierProvider.notifier).toggle(task.id);
              },
              title: Text(task.id),
            ),
        ],
      ),
    );
  }
}

mhadaily

final tasksNotifierProvider = StateNotifierProvider<TasksNotifier, List<Task>>((ref) {
  return TasksNotifier();
});
class MyHomePage extends ConsumerWidget {
  const MyHomePage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final List<Task> tasks = ref.watch(tasksNotifierProvider);
    return Scaffold(
      body: ListView(
        children: [
          for (final task in tasks)
            CheckboxListTile(
              value: task.completed,
              onChanged: (value) {
                ref.read(tasksNotifierProvider.notifier).toggle(task.id);
              },
              title: Text(task.id),
            ),
        ],
      ),
    );
  }
}

mhadaily

ChangeNotifierProvider

is used to listen to and expose a ChangeNotifier from Flutter itself.
an easy transition from package:provider when using its ChangeNotifierProvider
supporting mutable state, even though immutable state is preferred

mhadaily

class Task {
  Task({
    required this.id,
    required this.completed,
  });
  String id;
  bool completed;
}
class TasksNotifier extends ChangeNotifier {
  final tasks = [
    Task(completed: false, id: '1'),
    Task(completed: true, id: '2')
  ];

  void toggle(String taskId) {
    for (final task in tasks) {
      if (task.id == taskId) {
        task.completed = !task.completed;
        notifyListeners();
      }
    }
  }
}

mhadaily

final tasksNotifierProvider = ChangeNotifierProvider<TasksNotifier>((ref) {
  return TasksNotifier();
});
class TaskListView extends ConsumerWidget {
  const TaskListView({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final List<Task> tasks = ref.watch(tasksNotifierProvider).tasks;
    return Scaffold(
      body: ListView(
        children: [
          for (final task in tasks)
            CheckboxListTile(
              value: task.completed,
              onChanged: (value) {
                ref.read(tasksNotifierProvider.notifier).toggle(task.id);
              },
              title: Text(task.id),
            ),
        ],
      ),
    );
  }
}

mhadaily

FutureProvider

for asynchronous code
performing and caching asynchronous operations (such as network requests)
nicely handling error/loading states of asynchronous operations
combining multiple asynchronous values into another value

listening to Firebase or web-sockets
rebuilding another provider every few seconds
removes the need to differentiate broadcast streams from normal streams.
it caches the latest value emitted by the stream

StreamProvider

mhadaily

@freezed
class Configuration with _$Configuration {
  @JsonSerializable(fieldRename: FieldRename.snake)
  factory Configuration({
    required String publicKey,
    required String privateKey,
    required String host,
  }) = _Configuration;

  factory Configuration.fromJson(Map<String, Object?> json) =>
      _$ConfigurationFromJson(json);
}

mhadaily

final configProvider = FutureProvider<Configuration>((ref) async {
  final content = json.decode(
    await rootBundle.loadString('assets/configurations.json'),
  ) as Map<String, Object?>;

  return Configuration.fromJson(content);
});

//...
Widget build(BuildContext context, WidgetRef ref) {
  AsyncValue<Configuration> config = ref.watch(configProvider);

  return config.when(
    loading: () => const CircularProgressIndicator(),
    error: (err, stack) => Text('Error: $err'),
    data: (config) {
      return Text(config.host);
    },
  );
}

mhadaily

final configProvider = FutureProvider<Configuration>((ref) async {
  final content = json.decode(
    await rootBundle.loadString('assets/configurations.json'),
  ) as Map<String, Object?>;

  return Configuration.fromJson(content);
});

//...
Widget build(BuildContext context, WidgetRef ref) {
  AsyncValue<Configuration> config = ref.watch(configProvider);

  return config.when(
    loading: () => const CircularProgressIndicator(),
    error: (err, stack) => Text('Error: $err'),
    data: (config) {
      return Text(config.host);
    },
  );
}

mhadaily

Combining

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);

final dioProvider = Provider((ref) => Dio());

final productsProvider = FutureProvider<List<Product>>((ref) async {
  final sortType = ref.watch(productSortTypeProvider);
  final http = ref.watch(dioProvider);
  final response = await http.get('$URL?sort=$sortType');
  return response.data.map((product) => Product.fromJson(product)).toList();
});

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);

final dioProvider = Provider((ref) => Dio());

final repositoryProvider = Provider((ref) => Repository(ref.read));

class Repository {
  Repository(this.read);
  final Reader read;
  Future<List<Product>> fetchProducts() async {
    final String sortType = read(productSortTypeProvider);
    final String dio = read(dioProvider);
    final response = await dio.get('/path', queryParameters: {
      'sortType': sortType,
    });
  return response.data.map((product) => Product.fromJson(product)).toList();
  }
}

mhadaily

DON'T CALL READ INSIDE THE BODY OF A PROVIDER

final myProvider = Provider((ref) {
  // Bad practice to call `read` here
  final value = ref.read(anotherProvider);
});

mhadaily

Do not listen to all changes if it's not needed!

// AVOID


final configProvider = StreamProvider<Configuration>(...);

final productsProvider = FutureProvider<List<Product>>((ref) async {
  final configs = await ref.watch(configProvider.future);

  return dio.get('${configs.host}/products');
});

mhadaily

"select" is your friend!

// PREFER


final configProvider = StreamProvider<Configuration>(...);

final productsProvider = FutureProvider<List<Product>>((ref) async {
  // Listens only to the host. If something else in the configurations
  // changes, this will not pointlessly re-evaluate our provider.

   final host = await ref.watch(
		configProvider.select((config) => config.host)
               );

  return dio.get('$host/products');
});

mhadaily

selectAsync (in version 2)

// PREFER


final configProvider = StreamProvider<Configuration>(...);

final productsProvider = FutureProvider<List<Product>>((ref) async {
  // Listens only to the host. If something else in the configurations
  // changes, this will not pointlessly re-evaluate our provider.

   final host = await ref.watch(
		configProvider.selectAsync((config) => config.host)
               );

  return dio.get('$host/products');
});

mhadaily

abstract class User {
  String get name;
  int get age;
}

//...

class MyWidget extends ConsumerWidget{

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // User user = ref.watch(userProvider);
    // return Text(user.name);
    
    String name = ref.watch(userProvider.select((user) => user.name));
    return Text(name);
  }
}

mhadaily

Modifiers

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);

final dioProvider = Provider((ref) => Dio());

// to destroy the state of a provider when it is no-longer used
final productsProvider = FutureProvider.autoDispose<List<Product>>((ref) async {
  final sortType = ref.watch(productSortTypeProvider);
  final http = ref.watch(dioProvider);
  final response = await http.get('$URL?sort=$sortType');
  
  // in version 1 
  ref.maintainState = true  
  // in version 2 
  // ref.keepAlive();

  return response.data.map((product) => Product.fromJson(product)).toList();
});

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);

final dioProvider = Provider((ref) => Dio());


final productProvider = FutureProvider.family<Product, String>(
	(ref, id) async {
      final http = ref.watch(dioProvider);
      final response = await http.get('$URL/$id');
      return Product.fromJson(response.data);
    }
);
//... 
Widget build(BuildContext context, WidgetRef ref) {
  final response = ref.watch(productProvider('id'));
}

mhadaily

final productSortTypeProvider = StateProvider<ProductSortType>(
  (ref) => ProductSortType.name,
);

final dioProvider = Provider((ref) => Dio());

// to destroy the state of a provider when it is no-longer used
final productProvider = FutureProvider
	.autoDispose
    .when<Product, String>((ref, id) async {
      final http = ref.watch(dioProvider);
      final response = await http.get('$URL/$id');
      // in version 1 
      ref.maintainState = true  
      // in version 2 
      // ref.keepAlive();
      return Product.fromJson(response.data);
});

mhadaily

PREFER using `autoDispose` when the parameter is not constant


final characters = FutureProvider
  .autoDispose
  .family<List<Character>, String>(
    (
      ref,
      filter,
    ) async {
      return fetchCharacters(filter: filter);
    },
  );

mhadaily

the parameter should have a consistent hashCode and ==

// the parameter should either be a primitive (bool/int/double/String), 
// a constant (providers), 
// or an immutable object that overrides == and hashCode.

This includes:

1- A tuple from tuple

2- Objects generated with Freezed or built_value

3- Objects using equatable

mhadaily

@freezed
abstract class MyParameter with _$MyParameter {
  factory MyParameter({
    required int userId,
    required Locale locale,
  }) = _MyParameter;
}

final exampleProvider = Provider.autoDispose.family<Something, MyParameter>(
(ref, myParameter) {
  print(myParameter.userId);
  print(myParameter.locale);
  // Do something with userId/locale
});

@override
Widget build(BuildContext context, WidgetRef ref) {
  int userId; // Read the user ID from somewhere
  final locale = Localizations.localeOf(context);

  final something = ref.watch(
    exampleProvider(MyParameter(userId: userId, locale: locale)),
  );

  ...
}

mhadaily

ProviderObserver

mhadaily

didAddProvider is called every time a provider was initialized, and the value exposed is value.

didDisposeProvider is called every time a provider was disposed.

didUpdateProvider is called every time by providers when they emit a notification.

mhadaily

class Logger extends ProviderObserver {
  @override
  void didUpdateProvider(
    ProviderBase provider,
    Object? previousValue,
    Object? newValue,
    ProviderContainer container,
  ) {
    print('''
{
  "provider": "${provider.name ?? provider.runtimeType}",
  "newValue": "$newValue"
}''');
  }
}

mhadaily

void main() {
  runApp(
    ProviderScope(
    	observers: [Logger()], 
        child: const MyApp(),
    ),
  );
}

/*
I/flutter (16783): {
I/flutter (16783):   "provider": "counter",
I/flutter (16783):   "newValue": "1"
I/flutter (16783): }
*/

mhadaily

ref.listen

mhadaily

class HomeView extends ConsumerWidget {
  const HomeView({Key? key}): super(key: key);

  @override
  Widget build(BuildContext context, WidgetRef ref) {
   ref.listen<String>(
      userProvider.select((user) => user.name),
      (String? previousName, String newName) {
          print('The user name changed $newName');

          // show a modal or snackbar!
      }
    );

    return Container();
  }
}

mhadaily

testing

mhadaily

1- No state should be preserved between test/testWidgets. That means no global state in the application, or all global states should reset after each test.

2- Being able to force our providers to have a specific state, either through mocking or by manipulating them until we reach the desired state.

3- While providers are declared as globals, the state of a provider is not global

4- ProviderContainer object is implicitly created by ProviderScope,

5- two testWidgets using providers do not share any state. As such, there is no need for any setUp/tearDown at all.

mhadaily

final counterProvider = StateProvider((ref) => 0);


class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Consumer(builder: (context, ref, _) {
        final counter = ref.watch(counterProvider);
        return ElevatedButton(
          onPressed: () => ref.read(counterProvider.notifier).state++,
          child: Text('$counter'),
        );
      }),
    );
  }
}

mhadaily

void main() {
  testWidgets('update the UI when incrementing the state', 
    (tester) async {
      await tester.pumpWidget(ProviderScope(child: MyApp()));

      expect(find.text('0'), findsOneWidget);
      expect(find.text('1'), findsNothing);

      await tester.tap(find.byType(ElevatedButton));
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
      expect(find.text('0'), findsNothing);
    }
    );
    testWidgets('the counter state is not shared between tests', 
      (tester) async {
      await tester.pumpWidget(ProviderScope(child: MyApp()));

      expect(find.text('0'), findsOneWidget);
      expect(find.text('1'), findsNothing);
    },
  );
}

mhadaily

final todoListProvider = FutureProvider((ref) async => <Todo>[]);
// ...
ProviderScope(
  overrides: [
    todoListProvider.overrideWithValue(
      AsyncValue.data(
      [Todo(id: '42', label: 'Hello', completed: true)]
      ),
    ),
  ],
  child: const MyApp(),
);

mhadaily

class Repository {
  Future<List<Product>> fetchProducts() async => [];
}

final repositoryProvider = Provider((ref) => Repository());

class FakeRepository implements Repository {
  @override
  Future<List<Product>> fetchProducts() async {
    return [
      Product(id: '42', label: 'Hello world', price: 200),
    ];
  }
}

class ProductUI extends StatelessWidget {
  const ProductUI({Key? key, required this.product}) : super(key: key);
  final Product product;
  @override
  Widget build(BuildContext context) {
    return Text(product.id);
  }
}

mhadaily

void main() {
  testWidgets('override repositoryProvider', (tester) async {
    await tester.pumpWidget(
      ProviderScope(
        overrides: [
          repositoryProvider.overrideWithValue(FakeRepository())
        ],

	// ...
    
    await tester.pump();
    
    /... 
        
    expect(tester.widgetList(find.byType(ProductUI)), [
      isA<ProductUI>()
          .having((s) => s.product.id, 'product.id', '42')
          .having((s) => s.product.label, 'product.label', 'Hello world')
          .having((s) => s.product.price, 'product.price', 200),
    ]);    
    
    
//...

mhadaily

Summary

mhadaily

Riverpod vs Provider

Providers

Best practices

Testing

Majid Hajian

find me on internet

mhadaily

Slides and link to source code

slides.com/mhadaily

mhadaily

Riverpod, A Reactive Caching and Data-binding Framework

By Majid Hajian

Riverpod, A Reactive Caching and Data-binding Framework

Riverpod is more just a state management package it is a framework by itself that does caching, data binding, DI, and more.

1,183

Majid Hajian

Majid Hajian is a passionate software developer with years of developing and architecting complex web and mobile applications. He is passionate about web platform especially flutter, IoT, PWAs, and performance.

A Reactive Caching and Data-binding Framework

Agenda

ME.dart

mhadaily

What it means for Provider

What it means for

Providers

1- Allows easily accessing that state in multiple locations

Why use providers?

2- Simplifies combining this state with others

3- Enables performance optimizations

4- Increases the testability of your application

5- Allows easy integration with advanced features

1- Provider

2- StateProvider

3- StateNotifierProvider

4- ChangeNotifierProvider

5- StreamProvider

Providers variants

5- FutureProvider

Providers variants

StateProvider

The watch method should not be called asynchronously, like inside an onPressed of an ElevatedButton. Nor should it be used inside initState and other State life-cycles.

In those cases, consider using ref.read instead.

StateNotifierProvider

ChangeNotifierProvider

FutureProvider

StreamProvider

Combining

DON'T CALL READ INSIDE THE BODY OF A PROVIDER

Do not listen to all changes if it's not needed!

"select" is your friend!

selectAsync (in version 2)

Modifiers

PREFER using autoDispose when the parameter is not constant

the parameter should have a consistent hashCode and ==

ProviderObserver

didAddProvider is called every time a provider was initialized, and the value exposed is value.

didDisposeProvider is called every time a provider was disposed.

didUpdateProvider is called every time by providers when they emit a notification.

ref.listen

testing

Summary

Riverpod, A Reactive Caching and Data-binding Framework

More from Majid Hajian

The `watch` method should not be called asynchronously, like inside an `onPressed` of an ElevatedButton. Nor should it be used inside `initState` and other State life-cycles.

In those cases, consider using `ref.read` instead.

PREFER using `autoDispose` when the parameter is not constant