AutoDisposeStreamProvider<State> class Null safety

Creates a stream and expose 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.

Constructors

AutoDisposeStreamProvider(Create<Stream<State>, AutoDisposeStreamProviderRef<State>> _create, {String? name, List<ProviderOrFamily>? dependencies, Family<dynamic, dynamic, ProviderBase>? from, Object? argument}): Creates a stream and expose its latest event.

Properties

allTransitiveDependencies → List<ProviderOrFamily>?: All the dependencies of a provider and their dependencies too.
latefinalinherited
argument → Object?: If this provider was created with the .family modifier, argument is variable used.
finalinherited
dependencies → List<ProviderOrFamily>?: The list of providers that this provider potentially depends on.
final
from → Family<dynamic, dynamic, ProviderBase>?: If this provider was created with the .family modifier, from is the .family instance.
finalinherited
future → AutoDisposeProviderBase<Future<State>>: {@template riverpod.streamprovider.future}
latefinal
hashCode → int: The hash code for this object.
read-onlyinherited
last → AutoDisposeProviderBase<Future<State>>: {@template riverpod.streamprovider.future}
read-only
name → String?: A custom label for providers.
finalinherited
originProvider → ProviderBase<AsyncValue<State>>: The provider that will be refreshed when calling ProviderContainer.refresh and that will be overridden when passed to ProviderScope.
read-onlyoverride
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
stream → AutoDisposeProviderBase<Stream<State>>: {@template riverpod.streamprovider.stream}
latefinal

Methods

create(covariant AutoDisposeStreamProviderElement<State> ref) → AsyncValue<State>: Initializes the state of a provider
override
createElement() → AutoDisposeStreamProviderElement<State>: An internal method that defines how a provider behaves.
override
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent method or property is accessed.
inherited
overrideWithProvider(AutoDisposeProviderBase<AsyncValue<State>> value) → Override: Overrides a provider with a value, ejecting the default behaviour.
inherited
overrideWithValue(AsyncValue<State> value) → Override: Overrides a provider with a value, ejecting the default behaviour.
inherited
select<Selected>(Selected selector(AsyncValue<State> value)) → ProviderListenable<Selected>: Partially listen to a provider.
inherited
toString() → String: A string representation of this object.
inherited
updateShouldNotify(AsyncValue<State> previousState, AsyncValue<State> newState) → bool: Called when a provider is rebuilt. Used for providers to not notify their listeners if the exposed value did not change.
override

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Constants

family → const AutoDisposeStreamProviderFamilyBuilder: A group of providers that builds their value from an external parameter.
AutoDisposeStreamProviderFamilyBuilder()