Flutter widget that refreshes itself periodically.

refreshable_builder.dart

import 'package:flutter/material.dart';

typedef RefreshableWidgetBuilder<T> = Widget Function(
    BuildContext context, T value);

typedef RefreshCall<T> = Future<T> Function();

class RefreshableBuilder<T> extends StatefulWidget {
  RefreshableBuilder({
    super.key,
    required this.builder,
    required this.refreshCall,
    this.initialValue,
    Duration? refreshRate,
  }) : refreshRate = refreshRate ?? Duration(seconds: 20);

  final RefreshableWidgetBuilder<T> builder;
  final RefreshCall<T> refreshCall;
  final Duration refreshRate;
  final T? initialValue;

  @override
  State<RefreshableBuilder<T>> createState() => _RefreshableBuilderState<T>();
}

class _RefreshableBuilderState<T> extends State<RefreshableBuilder<T>> {
  T? initialValue;
  late Stream<T> stream;
  T? cached;

  @override
  void initState() {
    if (widget.initialValue != null) {
      initialValue = widget.initialValue!;
    }
    stream = Stream.periodic(widget.refreshRate).asyncMap((_) async {
      try {
        final data = await widget.refreshCall();
        cached = data;
        return data;
      } catch (e) {
        if (cached != null) {
          return cached!;
        }
        rethrow;
      }
    });

    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return StreamBuilder<T>(
      initialData: initialValue,
      stream: stream,
      builder: (BuildContext context, AsyncSnapshot<T> snapshot) {
        if (snapshot.hasData) {
          return widget.builder(context, snapshot.data!);
        } else {
          return Center(
            child: CircularProgressIndicator(),
          );
        }
      },
    );
  }
}

Some relevant issues that can help
https://stackoverflow.com/questions/66539533/in-flutter-can-i-put-futurebuilderstring-inside-a-timer
https://stackoverflow.com/questions/72025771/futurebuilder-update-by-timer