example/example.md

Hyper Storage Flutter Examples #

This file provides examples of how to use the hyper_storage_flutter package to build reactive user interfaces in Flutter.

Listening to a Single Key #

There are multiple ways to listen to a single key in your storage.

• Using ItemHolder: ItemHolder is listenable and can be streamed too.
• Using ItemHolder.asValueNotifier: This is a convenient way to get a ValueNotifier for a specific key.
• Using storage.stream<E>(key): This provides a stream of changes for a specific key.

You can use asValueNotifier on an ItemHolder to obtain a ValueNotifier for a specific key. This allows you to rebuild your UI automatically whenever the value of that key changes.

Using ItemHolder as ValueNotifier. #

Note: ItemHolder.asValueNotifier must be called outside of the build method, typically in initState as it will create a new ValueNotifier each time it is called.

import 'package:flutter/material.dart';
import 'package:hyper_storage/hyper_storage.dart';
import 'package:hyper_storage_flutter/hyper_storage_flutter.dart';

class CounterScreen extends StatefulWidget {
  final HyperStorage storage;

  const CounterScreen({super.key, required this.storage});

  @override
  State<CounterScreen> createState() => _CounterScreenState();
}

class _CounterScreenState extends State<CounterScreen> {
  late final ItemHolder<int> _counterHolder;
  late final ValueNotifier<int?> _counterNotifier;

  @override
  void initState() {
    super.initState();
    _counterHolder = widget.storage.itemHolder<int>('counter');
    _counterNotifier = _counterHolder.asValueNotifier();
  }

  @override
  void dispose() {
    _counterNotifier.dispose();
    _counterHolder.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ValueListenableBuilder<int?>(
          valueListenable: _counterNotifier,
          builder: (context, counter, child) {
            return Text('Counter: ${counter ?? 0}');
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () async {
          final currentCounter = await _counterHolder.get() ?? 0;
          await _counterHolder.set(currentCounter + 1);
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}

Using ItemHolder with StreamBuilder. #

Note: It is safe to reuse the same ItemHolder instance multiple times without disposing it, as it manages its own resources. Calling itemHolder multiple times with the same key will return the same instance.

import 'package:flutter/material.dart';
import 'package:hyper_storage/hyper_storage.dart';
import 'package:hyper_storage_flutter/hyper_storage_flutter.dart';

class CounterScreen extends StatefulWidget {
  final HyperStorage storage;

  const CounterScreen({super.key, required this.storage});

  @override
  State<CounterScreen> createState() => _CounterScreenState();
}

class _CounterScreenState extends State<CounterScreen> {
  late final ItemHolder<int> _counterHolder = widget.storage.itemHolder<int>('counter');

  @override
  void dispose() {
    _counterHolder.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: StreamBuilder<int?>(
          stream: _counterHolder,
          builder: (context, snapshot) {
            return Text('Counter: ${snapshot.data ?? 0}');
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () async {
          final currentCounter = await _counterHolder.get() ?? 0;
          await _counterHolder.set(currentCounter + 1);
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}

Using streams with StreamBuilder. #

Note: storage.stream<E>(key) is safe to call inside the build method as it manages the stream internally.

import 'package:flutter/material.dart';
import 'package:hyper_storage/hyper_storage.dart';
import 'package:hyper_storage_flutter/hyper_storage_flutter.dart';

class CounterScreen extends StatefulWidget {
  final HyperStorage storage;

  const CounterScreen({super.key, required this.storage});

  @override
  State<CounterScreen> createState() => _CounterScreenState();
}

class _CounterScreenState extends State<CounterScreen> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: StreamBuilder<int?>(
          stream: widget.storage.stream<int>('counter'),
          builder: (context, snapshot) {
            return Text('Counter: ${snapshot.data ?? 0}');
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () async {
          final currentCounter = await widget.storage.getInt('counter') ?? 0;
          await widget.storage.setInt('counter', currentCounter + 1);
        },
        child: const Icon(Icons.add),
      ),
    );
  }
}