async_value_builder.dart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

class AsyncValueBuilder<R> extends StatelessWidget {
  const AsyncValueBuilder({
    Key? key,
    required this.asyncValue,
    required this.builder,
  }) : super(key: key);

  final AsyncValue<R> asyncValue;
  final Widget Function(BuildContext context, R data) builder;

  @override
  Widget build(BuildContext context) {
    return asyncValue.when(
      data: (data) => builder(context, data),
      error: (error, stackTrace) => Center(child: Text('$error')),
      loading: () => const Center(child: CircularProgressIndicator.adaptive()),
    );
  }
}

// Usage

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'AsyncValueBuilder Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: AsyncValueBuilder<String>(
          asyncValue: const AsyncValue.data('ABC'),
          builder: (context, value) {
            return Text(value);
          },
        ),
      ),
    );
  }
}