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Many Lints

avoid_build_context_in_providers

v0.8.0 Warning Riverpod State

Flags a BuildContext parameter on a @riverpod provider — either a functional provider or a method of a @riverpod class.

Why use this rule

Section titled “Why use this rule”

Providers outlive the widgets that read them. A BuildContext held by a provider can easily refer to a widget that has already been unmounted, and using it then throws dependOnInheritedWidgetOfExactType was called on a defunct widget — or quietly reads stale inherited data. Passing the value you need instead keeps the provider independent of the widget tree, which is also what makes it testable without pumping a widget.

See also: Riverpod families

Don’t

Section titled “Don’t”

A provider that takes the context so it can read the locale itself. The context it captured belongs to a widget that may already be gone by the time the provider rebuilds:

@riverpod
Future<List<Article>> articles(Ref ref, BuildContext context) { // LINT
  final locale = Localizations.localeOf(context);
  return api.fetchArticles(locale.languageCode);
}

Every method of a @riverpod class is checked, not just build — an action method that takes a context to show a snackbar afterwards is the same problem:

@riverpod
class Checkout extends _$Checkout {
  @override
  CheckoutState build() => const CheckoutState.idle();


  Future<void> submit(BuildContext context) async { // LINT
    await api.submit();
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('Order placed')),
    );
  }
}

Do

Section titled “Do”

Pass the value the provider needs, and let the family key on it:

@riverpod
Future<List<Article>> articles(Ref ref, String languageCode) =>
    api.fetchArticles(languageCode);


// At the call site, where a context is legitimately in scope:
class ArticleList extends ConsumerWidget {
  const ArticleList({super.key});


  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final locale = Localizations.localeOf(context);
    final articles = ref.watch(articlesProvider(locale.languageCode));
    return Text('${articles.valueOrNull?.length}');
  }
}

Let the notifier report the outcome through its state, and let the widget do the UI work:

@riverpod
class Checkout extends _$Checkout {
  @override
  CheckoutState build() => const CheckoutState.idle();


  Future<void> submit() async {
    state = const CheckoutState.submitting();
    await api.submit();
    state = const CheckoutState.placed();
  }
}


class CheckoutButton extends ConsumerWidget {
  const CheckoutButton({super.key});


  @override
  Widget build(BuildContext context, WidgetRef ref) {
    ref.listen(checkoutProvider, (previous, next) {
      if (next is CheckoutPlaced) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('Order placed')),
        );
      }
    });


    return ElevatedButton(
      onPressed: () => ref.read(checkoutProvider.notifier).submit(),
      child: const Text('Place order'),
    );
  }
}

Known limitations

Section titled “Known limitations”

Only @riverpod declarations are checked. An ordinary function or class taking a BuildContext is left alone:

Locale readLocale(BuildContext context) => Localizations.localeOf(context);

The parameter type must resolve to exactly BuildContext. A subtype, or a context wrapped in some project-specific holder, is not reported.

Configuration

Section titled “Configuration”

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

To turn it off:

many_lints.yaml
rules:
  avoid_build_context_in_providers: false

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

Section titled “Related rules”