AutoDisposeStreamProvider<T> class

Creates a stream and exposes its latest event.

StreamProvider is identical in behavior/usage to FutureProvider, modulo the fact that the value created is a Stream instead of a Future.

It can be used to express a value asynchronously loaded that can change over time, such as an editable Message coming from a web socket:

final messageProvider = StreamProvider.autoDispose<String>((ref) async* {
  // Open the connection
  final channel = IOWebSocketChannel.connect('ws://echo.websocket.org');

  // Close the connection when the stream is destroyed
  ref.onDispose(() => channel.sink.close());

  // Parse the value received and emit a Message instance
  await for (final value in channel.stream) {
    yield value.toString();
  }
});

Which the UI can then listen:

Widget build(BuildContext context, WidgetRef ref) {
  AsyncValue<String> message = ref.watch(messageProvider);

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

Note: When listening to web sockets, firebase, or anything that consumes resources, it is important to use StreamProvider.autoDispose instead of simply StreamProvider.

This ensures that the resources are released when no longer needed as, by default, a StreamProvider is almost never destroyed.

See also:

• Provider, a provider that synchronously creates a value
• FutureProvider, a provider that asynchronously exposes a value that can change over time.
• future, to obtain the last value emitted by a Stream.
• StreamProvider.family, to create a StreamProvider from external parameters
• StreamProvider.autoDispose, to destroy the state of a StreamProvider when no longer needed.

Inheritance

• Object
• ProviderOrFamily
• ProviderBase<AsyncValue<T>>
• AutoDisposeStreamProvider

Constructors

AutoDisposeStreamProvider(Stream<T> _createFn(AutoDisposeStreamProviderRef<T> ref), {String? name, Iterable<ProviderOrFamily>? dependencies, @Deprecated('Will be removed in 3.0.0') Family<Object?>? from, @Deprecated('Will be removed in 3.0.0') Object? argument, @Deprecated('Will be removed in 3.0.0') DebugGetCreateSourceHash? debugGetCreateSourceHash})

Creates a stream and exposes its latest event.

AutoDisposeStreamProvider.internal(Stream<T> _createFn(AutoDisposeStreamProviderRef<T> ref), {required String? name, required Iterable<ProviderOrFamily>? dependencies, required Iterable<ProviderOrFamily>? allTransitiveDependencies, required DebugGetCreateSourceHash? debugGetCreateSourceHash, Family<Object?>? from, Object? argument})

An implementation detail of Riverpod

Properties

allTransitiveDependencies → Iterable<ProviderOrFamily>?

All the dependencies of a provider and their dependencies too.

final, inherited

argument → Object?

If this provider was created with the .family modifier, argument is the variable that was used.

final, inherited

debugGetCreateSourceHash → DebugGetCreateSourceHash?

A debug-only fucntion for obtaining a hash of the source code of the initialization function.

final, inherited

dependencies → Iterable<ProviderOrFamily>?

The list of providers that this provider potentially depends on.

final, inherited

from → Family<Object?>?

If this provider was created with the .family modifier, from is the .family instance.

final, inherited

future → Refreshable<Future<T>>

late, final

hashCode → int

The hash code for this object.

no setter, inherited

name → String?

A custom label for providers.

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

stream → Refreshable<Stream<T>>

late, final

Methods

addListener(Node node, void listener(AsyncValue<T>? previous, AsyncValue<T> next), {required void onError(Object error, StackTrace stackTrace)?, required void onDependencyMayHaveChanged()?, required bool fireImmediately}) → ProviderSubscription<AsyncValue<T>>

Starts listening to this transformer

inherited

createElement() → AutoDisposeStreamProviderElement<T>

An internal method that defines how a provider behaves.

override

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

overrideWith(Create<Stream<T>, AutoDisposeStreamProviderRef<T>> create) → Override

Override the provider with a new initialization function.

read(Node node) → AsyncValue<T>

Obtains the result of this provider expression without adding listener.

inherited

select<Selected>(Selected selector(AsyncValue<T> value)) → ProviderListenable<Selected>

Partially listen to a provider.

inherited

selectAsync<Output>(Output selector(T data)) → ProviderListenable<Future<Output>>

A variant of select for asynchronous values

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Constants

family → const AutoDisposeStreamProviderFamily<R, Arg> Function<R, Arg>(Stream<R> _createFn(AutoDisposeStreamProviderRef<R> ref, Arg arg), {Iterable<ProviderOrFamily>? dependencies, String? name})

A group of providers that builds their value from an external parameter.