StateNotifierProvider<Notifier extends StateNotifier<Value>, Value> class Null safety

Creates a StateNotifier and expose its current state.

This provider is used in combination with package:state_notifier.

Combined with StateNotifier, StateNotifierProvider can be used to manipulate advanced states, that would otherwise be difficult to represent with simpler providers such as Provider or FutureProvider.

For example, you may have a todo-list, where you can add and remove and complete a todo. Using StateNotifier, you could represent such state as:

class TodosNotifier extends StateNotifier<List<Todo>> {
  TodosNotifier(): super([]);

  void add(Todo todo) {
    state = [...state, todo];
  }

  void remove(String todoId) {
    state = [
      for (final todo in state)
        if (todo.id != todoId) todo,
    ];
  }

  void toggle(String todoId) {
    state = [
      for (final todo in state)
        if (todo.id == todoId) todo.copyWith(completed: !todo.completed),
    ];
  }
}

Which you can then pass to a StateNotifierProvider like so:

final todosProvider = StateNotifierProvider((ref) => TodosNotifier());

And finally, you can interact with it inside your UI:

Widget build(BuildContext context, ScopedReader watch) {
  // rebuild the widget when the todo list changes
  List<Todo> todos = watch(todosProvider);

  return ListView(
    children: [
      for (final todo in todos)
        CheckboxListTile(
           value: todo.completed,
           // When tapping on the todo, change its completed status
           onChanged: (value) => context.read(todosProvider).toggle(todo.id),
           title: Text(todo.description),
        ),
    ],
  );
}
Inheritance
Annotations

Constructors

StateNotifierProvider(Create<Notifier, ProviderReference> _create, {String? name})
Creates a StateNotifier and expose its current state. [...]

Properties

argument Object?
If this provider was created with the .family modifier, argument is variable used.
read-only, inherited
debugId String
A unique identifier for this provider, used by devtools to differentiate providers [...]
late, final, inherited
from StateNotifierProviderFamily<Notifier, Value, Object?>?
If this provider was created with the .family modifier, from is the .family instance.
read-only, override
hashCode int
The hash code for this object. [...]
@nonVirtual, read-only, inherited
name String?
A custom label for providers. [...]
final, inherited
notifier AlwaysAliveProviderBase<Notifier, Notifier>
Obtains the StateNotifier associated with this StateNotifierProvider, without listening to it. [...]
late, final
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited

Methods

create(ProviderReference ref) → Notifier
override
createElement() ProviderElement<Notifier, Value>
An internal method that defines how a provider behaves.
inherited
createState() → _StateNotifierProviderState<Notifier, Value>
An internal method that creates the state of a provider.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
inherited
overrideWithProvider(StateNotifierProvider<Notifier, Value> provider) Override
Overrides the behavior of a provider with a another provider. [...]
overrideWithValue(Notifier value) Override
Overrides the behavior of a provider with a value. [...]
inherited
select<Selected>(Selected selector(Value value)) ProviderListenable<Selected>
Partially listen to a provider. [...]
inherited
toString() String
A string representation of this object. [...]
inherited

Operators

operator ==(Object other) bool
The equality operator. [...]
inherited

Constants

autoDispose → const AutoDisposeStateNotifierProviderBuilder
Marks the provider as automatically disposed when no-longer listened. [...]
AutoDisposeStateNotifierProviderBuilder()
family → const StateNotifierProviderFamilyBuilder
A group of providers that builds their value from an external parameter. [...]
StateNotifierProviderFamilyBuilder()