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Simon Pham
Simon Pham

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Store key-value data in Flutter using hive - but easier

#flutter #hive #dart

Introduction

A while ago, I posted a post about how to store key-value data using shared_preferences package.

However, shared_preferences is not pure Dart and depends on the platform, which might not be a good performance choice. So, I decided to look for another approach, and I found hive.

After using the package for several projects, I grew tired of writing/copying boilerplate code just to store my key-value data. I came up with an idea of writing a wrapper package for hive. This package should meet these criteria:

  • Support data encryption
  • Support Lazy loading of data
  • Support store data using Enum key
  • Support Listenable
  • And be EASY to use.

Links

Guide to use:

You can either define your boxes as Singleton classes or use a service locator like
get_it.

Let's take a look at the guide to define a simple SettingsBox to store your settings using singleton class approach.

1. Define box keys 🔑 

enum Settings {
  key, // Use as box key. You can use a String constant instead.

  /// Other keys below...
  themeMode,
  counter,
}
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2. Define a box 📦 


import 'package:easy_hive/easy_hive.dart';

class SettingsBox extends EasyBox {
  @override
  String get boxKey => Settings.key.toString();

  /// Singleton.
  static final SettingsBox _instance = SettingsBox._();

  factory SettingsBox() => _instance;

  SettingsBox._();
}
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3. Initialize box 🚀 


import 'package:easy_hive/easy_hive.dart';

Future<void> main() async {
  await EasyBox.initialize();

  await SettingsBox().init();

  // runApp...
}
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4. Define getter & setter for your data 💄 

extension GeneralSettingsExtension on SettingsBox {
  ThemeMode get themeMode {
    final index = get(
      Settings.themeMode,
      defaultValue: 0,
    );
    return ThemeMode.values[index];
  }

  set themeMode(ThemeMode value) => put(Settings.themeMode, value.index);

  int get counter => get(Settings.counter, defaultValue: 0);

  set counter(int value) => put(Settings.counter, value);
}
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5. Use it anywhere 🔥 

  Text(
    'You have pushed: ${SettingsBox().counter} times.',
    style: Theme.of(context).textTheme.headlineMedium,
  ),
  FilledButton(
    onPressed: () {
      SettingsBox().counter++;
    },
    child: Text('Increment'),
  ),
  FilledButton(
    onPressed: () {
      SettingsBox().themeMode = ThemeMode.dark;
    },
    child: Text('Dark Theme'),
  ),
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Advanced Usage 😈

Enable encryption 🔐

1. Install easy_hive_encryption:

2. Add EncryptionMixin to your box class: 

class SettingsBox extends EasyBox with EncryptionMixin {
  @override
  String get boxKey => Settings.key.toString();

  /// Override encryption key name (optional).
  @override
  String get encryptionKeyName => "your-own-key-name";
}
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3. Follow flutter_secure_storage's guide for specific platform setup.

Enable lazy loading 🐢

1. Add LazyMixin to your box class: 

class SettingsBox extends EasyBox with LazyMixin {
  @override
  String get boxKey => Settings.key.toString();
}
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2. Use await to get your value: 

extension GeneralSettingsExtension on SettingsBox {
  Future<ThemeMode> getThemeMode() async {
    final index = await get(
      Settings.themeMode,
      defaultValue: 0,
    );
    return ThemeMode.values[index];
  }
}
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Listen to value changes 🎧

Recommended: Use RefreshableBox + provider:

1. Extends RefreshableBox instead of EasyBox: 

class SettingsBox extends RefreshableBox {
  @override
  String get boxKey => Settings.key.toString();
}
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2. Use it as a provider: 

  ChangeNotifierProvider(
    create: (_) => SettingsBox(),
    child: SomeWidget(),
  ),
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// Inside SomeWidget.
Text(
  'You have pushed: '
  '${context.select((SettingsBox _) => _.counter)} times.',
),
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For more info, see provider package.

Or if you don't want RefreshableBox:

Just use ValueListenableBuilder to listen to changes. 

ValueListenableBuilder(
  valueListenable: [
    Settings.counter,
  ].of(SettingsBox()),
  builder: (context, _, __) {
    return Text(
      '${SettingsBox().counter}',
    );
  },
),
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This guide is taken from easy_hive repository.

Happy Coding 🦊

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