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Tag: dart

72 posts · Page 3 of 8

2026-07-13 flutter dart async

How to guard setState with the mounted check after an async gap in Flutter

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.

2026-07-09 migration flutter dart

Migrate from Riverpod 2.x to Riverpod 3.0 in Flutter

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.

2026-07-07 flutter dart

Flutter 3.44: Read the Physical Screen Corner Radius from MediaQuery

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+.

2026-07-07 flutter dart go-router

go_router vs auto_route vs Navigator 2.0 in Flutter

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.

2026-07-07 comparison flutter dart

shrinkWrap vs Expanded vs slivers for long lists in Flutter: which should you pick?

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.

2026-07-06 errors flutter dart

Fix: Riverpod 3.0 throws ProviderException instead of the original error

Riverpod 3.0 wraps errors thrown while reading a provider in a ProviderException. Catch that type and read e.exception to get your original error back, or use AsyncValue.error which is unwrapped.

2026-07-05 dart flutter

Dot Shorthands in Dart 3.12: Drop the Type Name in Flutter Code

Dot shorthands went stable in Dart 3.12.2. Write .center or .new and let the compiler infer the type from context. Here is how they work across enums, static members, and constructors.

2026-07-05 errors flutter dart

Fix: Cannot provide both a color and a decoration in a Flutter Container

Move the color inside the decoration: use decoration: BoxDecoration(color: ...) instead of passing both color and decoration to the same Container.

2026-07-05 errors flutter dart

Fix: Incorrect use of ParentDataWidget. Expanded widgets must be placed inside Flex widgets (Flutter)

This error means an Expanded or Flexible is not a direct child of a Row, Column, or Flex. Move it directly under the flex widget, or drop Expanded if the parent is not a flex.

2026-07-05 errors flutter dart

Fix: A RenderViewport expected a child of type RenderSliver but received a child of type RenderBox (Flutter CustomScrollView)

The slivers list of a CustomScrollView only accepts slivers. Wrap box widgets in SliverToBoxAdapter, or swap ListView/Padding/Column for SliverList and SliverPadding.