provider_parameters

v0.8.0 Warning Riverpod State

Flags an argument passed to a family provider that has no stable equality — a non-const collection literal, a closure, or an instance of a class that does not override ==.

Why use this rule

Riverpod caches one provider instance per family argument, keyed by ==. An argument that allocates a new object on every build never compares equal to the previous one, so Riverpod treats each rebuild as a brand-new provider: the old one is disposed, state is lost, and any network request behind it runs again. The symptom is an infinite rebuild loop or a widget that never keeps its data — both hard to trace back to the argument.

See also: Riverpod families

Don’t

// A new list every build — never equal to the last one
ref.watch(myProvider([1, 2, 3]));

// A new closure every build
ref.watch(myProvider(() => 42));

// Foo does not override ==, so each instance is distinct
ref.watch(myProvider(Foo()));

Do

class Foo {
  const Foo(this.id);
  final int id;

  @override
  bool operator ==(Object other) => other is Foo && other.id == id;

  @override
  int get hashCode => id.hashCode;
}

void watchStableValues(WidgetRef ref) {
  // Const values are canonicalized, so equality holds.
  ref.watch(myProvider(const [1, 2, 3]));
  ref.watch(myProvider(const Foo(1)));

  // Primitives compare by value.
  ref.watch(myProvider(42));
}

Configuration

This rule is in the recommended preset, so it is on with preset: recommended or preset: opinionated. Add it to preset: core with provider_parameters: true.

To turn it off:

many_lints.yaml

rules:
  provider_parameters: false

To keep the rule on but skip certain paths, use per-rule exclude.

Related rules

• missing_provider_scope — Flutter applications using Riverpod must have a ProviderScope at the root of the widget tree.
• async_value_nullable_pattern — Matching AsyncValue(:final value?) on a nullable value hides a legitimate null result.
• avoid_build_context_in_providers — Providers outlive widgets, so they should not receive a BuildContext.
• avoid_ref_inside_state_dispose — Avoid accessing ref inside the dispose method of a ConsumerState.