Persistent (Theme & Localization) Storage

[esmaeil-ahmadipour]

Overview

Feature Description

Implement persistent localization storage and app state initialization to ensure the selected language, theme, and other relevant settings persist across app restarts.

Click to expand the scenario

Scenario: Language and Theme Persistence on Restart

A user selects French as their preferred language and dark mode as their theme. When reopening the app, it should automatically display in French with the dark theme applied, without requiring the user to reselect them.

References

• Platform-Specific Implementations:
  Ensure language, theme, and app state are saved and loaded correctly across iOS, Android, and Web.

• Related Issue:

  • Implement Localization Management
  • Implement Theme Management

• Tools:

  • SharedPreferences

FOLDER STRUCTURE

src
│
└──lib/
    ├── features ....
    └── core/
        ├── constants/
        │   └── app_constants.dart # App-wide constants (e.g., all keys used in  shared_preferences_service , etc )
        └── services/
            └── shared_preferences_service.dart # SharedPreferences wrapper for app-wide usage

Proposed Changes

• Save and load user language, theme, and other app state using SharedPreferences.
• Initialize app with saved preferences (language and theme) on startup.

[phoenixit99]

📊 Current Status:

Progress: 100%
✔️ Completed Tasks:

Implemented localization.
Implemented theme.

🔄 Additional Information:

The default language has been set to English.
The default theme is configured to the system preference.

[esmaeil-ahmadipour]

@phoenixit99, I reviewed the code and found the following areas for improvement:

1. We need a singleton object of SharedPreferences. I suggest using this code to reduce the cost of creating and using an asynchronous object:

locator code

/// The dependency injection container used throughout the application.
final locator = GetIt.instance;

/// Sets up and registers the shared preferences instance.
///
/// Ensures a `SharedPreferences` instance is available.
/// Creates a new instance if `param` is null.
/// Registers the instance as a singleton in `locator`.
///
/// **Parameters:**
///
/// * `param`: An optional `SharedPreferences` instance.
///   If provided, this instance will be used.
///   Otherwise, a new instance will be created.
///
/// **See also:**
///
/// * [SharedPreferences]
Future<SharedPreferences> setupSharedPreferences(
    {SharedPreferences? param}) async {
  final prefs = param ?? await SharedPreferences.getInstance();
  return locator.registerSingleton<SharedPreferences>(prefs);
}

---

2- The tests related to language and theme have failed and need to be fixed. To write tests for SharedPreferences , we need to add the mocktail: ^1.0.4 library. The code is expected to be written as follows:

locator code

/// The dependency injection container used throughout the application.
final locator = GetIt.instance;

/// Initializes all necessary dependencies for the application.
///
/// This function registers all required services, repositories, and other dependencies 
/// within the [locator] (GetIt instance).
void initDependencies() {
  // ... some codes need using as singleton
}

/// A mock implementation of `SharedPreferences` for testing purposes.
class MockSharedPreferences extends Mock implements SharedPreferences {}

/// Sets up the testing environment.
///
/// Initializes the `TestWidgetsFlutterBinding`, creates a mock `SharedPreferences` 
/// instance, initializes dependencies, and sets up the list of providers.
void main() {
  TestWidgetsFlutterBinding.ensureInitialized();

  late SharedPreferences sharedPreferencesObject;
  late List<BloProvider> providers; 

  setUpAll(() {
    sharedPreferencesObject = MockSharedPreferences();
    setupSharedPreferences(param: sharedPreferencesObject).then((_) {
      initDependencies();
      providers = [
        // ... scope of bloc providers
      ];
    });
  });


/// write main test code :

  group(
    'testing sample screen',
    () {
    /// bla bla bla
    }
}

[phoenixit99]

@phoenixit99, I reviewed the code and found the following areas for improvement:

1. We need a singleton object of SharedPreferences. I suggest using this code to reduce the cost of creating and using an asynchronous object:

locator code
2- The tests related to language and theme have failed and need to be fixed. To write tests for SharedPreferences , we need to add the mocktail: ^1.0.4 library. The code is expected to be written as follows:

locator code

Thanks @esmaeil-ahmadipour . This has been really helpful and has saved me a lot of time.