Tag: dart

Riverpod 3.0 retries a failed provider up to 10 times by default. Pass a retry function that returns null on ProviderScope, ProviderContainer, or an individual provider to turn it off or bound it.

This runtime error means a null reached a cast expecting a non-nullable type, almost always from JSON. Make the field nullable, or supply a default before the cast runs.

This error means the BuildContext you passed is above the Scaffold or ScaffoldMessenger, not below it. Wrap the caller in a Builder, extract it into its own widget, or use a GlobalKey.

Wrap the same widget on both routes in a Hero with an identical tag and Flutter animates its position and size across the navigation. Full guide: images, flightShuttleBuilder, createRectTween, RectTween arcs, gesture transitions, and the tag collisions that break it. Tested on Flutter 3.44, Dart 3.12.

A stream keeps emitting after the user leaves the screen, its onData calls setState on a disposed State, and Flutter throws. Store the subscription, cancel it in dispose before super.dispose, and the callback can never fire on a dead widget. The full pattern for Flutter 3.44.

After an await, the widget may already be disposed, and calling setState throws. Guard the resume with if (!mounted) return; and, better, cancel the work that triggers it. The full pattern for Flutter 3.44.

A step-by-step upgrade from flutter_riverpod 2.x to 3.x: bump the packages, move StateProvider and friends to the legacy import, drop the AutoDispose and Family ref types, handle ProviderException wrapping and automatic retry, and fix the == notification filtering that silently drops StreamProvider events. Tested on Flutter 3.44, Dart 3.x, flutter_riverpod 3.3.2.

Flutter 3.44 exposes the device's rounded display corners through MediaQuery.displayCornerRadiiOf. Stop guessing a magic radius and clip your UI to the exact hardware curve on Android API 31+.

go_router and auto_route both sit on top of Navigator 2.0, so the real choice is declarative URL routing vs code-generated typed routes vs hand-rolling the Router API. A decision matrix with config for each, and when raw Navigator still wins.

For a long list, never use shrinkWrap. Use Expanded when the list is the only scrollable, and slivers (CustomScrollView) when it shares a scroll with other sections. Here is why, with a build-count benchmark.