shared_preference_signals 1.0.1

A Flutter package that provides reactive SharedPreferences integration using signals.

example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:signals/signals.dart';
import 'package:signals/signals_flutter.dart';
import 'package:shared_preference_signals/shared_preference_signals.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Shared Preference Signals Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({super.key});

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  // Example 1: User profile signal
  late final Signal<User?> userSignal = jsonSharedPreferenceSignal<User>(
    key: 'user_profile',
    value: null,
    fromJson: User.fromJson,
    toJson: (user) => user.toJson(),
  );

  // Example 2: Theme mode signal
  late final Signal<ThemeMode> themeSignal =
      enumSharedPreferenceSignal<ThemeMode>(
    key: 'theme_mode',
    value: ThemeMode.system,
    fromString: ThemeMode.values.byName,
  );

  // Example 3: App settings signal
  late final Signal<AppSettings?> settingsSignal =
      jsonSharedPreferenceSignal<AppSettings>(
    key: 'app_settings',
    value: AppSettings.defaultSettings(),
    fromJson: AppSettings.fromJson,
    toJson: (settings) => settings.toJson(),
  );

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Shared Preference Signals Demo'),
        actions: [
          // Theme mode switcher
          IconButton(
            icon: Icon(themeSignal.value == ThemeMode.dark
                ? Icons.light_mode
                : Icons.dark_mode),
            onPressed: () {
              themeSignal.value = themeSignal.value == ThemeMode.dark
                  ? ThemeMode.light
                  : ThemeMode.dark;
            },
          ),
        ],
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            // User Profile Section
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text(
                      'User Profile',
                      style: TextStyle(
                        fontSize: 20,
                        fontWeight: FontWeight.bold,
                      ),
                    ),
                    const SizedBox(height: 16),
                    Watch((context) {
                      final user = userSignal.value;
                      if (user == null) {
                        return ElevatedButton(
                          onPressed: () {
                            userSignal.value = User(
                              name: 'John Doe',
                              age: 30,
                            );
                          },
                          child: const Text('Create User Profile'),
                        );
                      }
                      return Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text('Name: ${user.name}'),
                          Text('Age: ${user.age}'),
                          const SizedBox(height: 8),
                          ElevatedButton(
                            onPressed: () {
                              userSignal.value = null;
                            },
                            child: const Text('Delete Profile'),
                          ),
                        ],
                      );
                    }),
                  ],
                ),
              ),
            ),
            const SizedBox(height: 16),

            // App Settings Section
            Card(
              child: Padding(
                padding: const EdgeInsets.all(16.0),
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    const Text(
                      'App Settings',
                      style: TextStyle(
                        fontSize: 20,
                        fontWeight: FontWeight.bold,
                      ),
                    ),
                    const SizedBox(height: 16),
                    Watch((context) {
                      final settings = settingsSignal.value;
                      if (settings == null) return const SizedBox.shrink();
                      return Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          SwitchListTile(
                            title: const Text('Enable Notifications'),
                            value: settings.enableNotifications,
                            onChanged: (value) {
                              settingsSignal.value = settings.copyWith(
                                enableNotifications: value,
                              );
                            },
                          ),
                          SwitchListTile(
                            title: const Text('Dark Mode'),
                            value: settings.darkMode,
                            onChanged: (value) {
                              settingsSignal.value = settings.copyWith(
                                darkMode: value,
                              );
                            },
                          ),
                          const SizedBox(height: 8),
                          Text('Last Updated: ${settings.lastUpdated}'),
                        ],
                      );
                    }),
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

// Example data models
class User {
  final String name;
  final int age;

  User({required this.name, required this.age});

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      name: json['name'] as String,
      age: json['age'] as int,
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'name': name,
      'age': age,
    };
  }
}

class AppSettings {
  final bool enableNotifications;
  final bool darkMode;
  final DateTime lastUpdated;

  AppSettings({
    required this.enableNotifications,
    required this.darkMode,
    required this.lastUpdated,
  });

  factory AppSettings.defaultSettings() {
    return AppSettings(
      enableNotifications: true,
      darkMode: false,
      lastUpdated: DateTime.now(),
    );
  }

  factory AppSettings.fromJson(Map<String, dynamic> json) {
    return AppSettings(
      enableNotifications: json['enableNotifications'] as bool,
      darkMode: json['darkMode'] as bool,
      lastUpdated: DateTime.parse(json['lastUpdated'] as String),
    );
  }

  Map<String, dynamic> toJson() {
    return {
      'enableNotifications': enableNotifications,
      'darkMode': darkMode,
      'lastUpdated': lastUpdated.toIso8601String(),
    };
  }

  AppSettings copyWith({
    bool? enableNotifications,
    bool? darkMode,
    DateTime? lastUpdated,
  }) {
    return AppSettings(
      enableNotifications: enableNotifications ?? this.enableNotifications,
      darkMode: darkMode ?? this.darkMode,
      lastUpdated: lastUpdated ?? this.lastUpdated,
    );
  }
}