consistent-update-render-object

added in: 1.6.0

Warns when an updateRenderObject method is absent or doesn't update all fields set in createRenderObject.

Example

❌ Bad:

// LINT
class ColorFiltered extends SingleChildRenderObjectWidget {
  const ColorFiltered({required this.value});

  final int value;

  @override
  RenderObject createRenderObject(BuildContext context) =>
      _ColorFilterRenderObject(colorFilter);
}

✅ Good:

class ColorFiltered extends SingleChildRenderObjectWidget {
  const ColorFiltered({required this.value});

  final int value;

  @override
  RenderObject createRenderObject(BuildContext context) =>
      _ColorFilterRenderObject(colorFilter);

  @override
  void updateRenderObject(BuildContext context, RenderObject renderObject) {
    (renderObject as _ColorFilterRenderObject).value = value;
  }
}

❌ Bad:

class _MenuItem extends SingleChildRenderObjectWidget {
  const _MenuItem({required this.value});

  final bool value;

  @override
  RenderObject createRenderObject(BuildContext context) {
    return _RenderMenuItem(value);
  }

  @override
  // LINT
  void updateRenderObject(BuildContext context, _RenderMenuItem renderObject) {}
}

✅ Good:

class _MenuItem extends SingleChildRenderObjectWidget {
  const _MenuItem({required this.value});

  final bool value;

  @override
  RenderObject createRenderObject(BuildContext context) {
    return _RenderMenuItem(value);
  }

  @override
  void updateRenderObject(BuildContext context, _RenderMenuItem renderObject) {
    renderObject.value = value;
  }
}

❌ Bad:

class _Decorator extends RenderObjectWidget {
  const _Decorator({
    required this.textDirection,
    required this.isFocused,
    required this.expands,
  });

  final TextDirection textDirection;
  final bool isFocused;
  final bool expands;

  @override
  _RenderDecoration createRenderObject(BuildContext context) {
    return _RenderDecoration(
      textDirection: textDirection,
      isFocused: isFocused,
      expands: expands,
    );
  }

  @override
  // LINT
  void updateRenderObject(
    BuildContext context,
    _RenderDecoration renderObject,
  ) {
    renderObject
      ..expands = expands
      ..textDirection = textDirection;
  }
}

✅ Good:

class _Decorator extends RenderObjectWidget {
  const _Decorator({
    required this.textDirection,
    required this.isFocused,
    required this.expands,
  });

  final TextDirection textDirection;
  final bool isFocused;
  final bool expands;

  @override
  _RenderDecoration createRenderObject(BuildContext context) {
    return _RenderDecoration(
      textDirection: textDirection,
      isFocused: isFocused,
      expands: expands,
    );
  }

  @override
  void updateRenderObject(
    BuildContext context,
    _RenderDecoration renderObject,
  ) {
    renderObject
      ..expands = expands
      ..isFocused = isFocused
      ..textDirection = textDirection;
  }
}

Example​

Example