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🧩 Dependency Injection (DI)

The Flutter Clean Starter uses get_it for dependency injection. This makes it easy to manage and access services, blocs, utilities, and other shared resources throughout the app in a clean and testable way.

📁 File: lib/_core/di.dart

import 'package:get_it/get_it.dart';

final GetIt di = GetIt.instance;
This file exposes a globally available singleton instance of GetIt, referenced as di throughout the app.

🔧 Registering Dependencies

Dependencies are typically registered in the bootstrap.dart or init_modules.dart files, during app initialization.

Example: Registering a singleton

di.registerLazySingleton<SomeService>(() => SomeServiceImpl());

  • registerLazySingleton: The object is created only when first used.
  • registerSingleton: The object is created immediately and shared.
  • registerFactory: A new instance is created on every retrieval.

Named Registration

You can optionally register dependencies with a name using instanceName: 

di.registerSingleton<SomeTabController>(
  SomeTabController(),
  instanceName: Constants.navTabsDiKey,
);
This is helpful for registering multiple instances of the same type for different purposes.

🧑‍💻 Accessing Dependencies

Anywhere in your app (routes, widgets, blocs, services, etc.), you can retrieve a registered dependency like this:

Example: Basic Access 

final authRepo = di<AuthRepository>();
Example: With instanceName 
final navRoutes = di.get<List<AdaptiveDestination>>(
  instanceName: Constants.navTabsDiKey,
);
This is used in app_router.dart to retrieve navigation tabs dynamically.

🔄 Why Use DI?

  • Decouples implementation from usage (e.g., blocs don’t need to know how services are built).
  • Improves testability by allowing mocks to be injected.
  • Centralizes configuration for shared app resources like HTTP clients, local storage, theme managers, etc.
  • get_it on pub.dev
  • bootstrap.dart: The main setup point for DI
  • init_modules.dart: Registers feature/module-specific services