---

name: dependency-injection-getit description: Guides GetIt dependency injection patterns for service registration. Use when creating new services, registering dependencies, or refactoring service architecture.

Dependency Injection with GetIt

Core Pattern

All services must be registered in dependency injection containers using GetIt.

Registration Locations

• Core Services: lib/injection_container_core.dart
• Domain Services: lib/injection_container.dart
• AI Services: lib/injection_container_ai.dart
• Payment Services: lib/injection_container_payment.dart
• Admin Services: lib/injection_container_admin.dart
• Other Modules: Separate containers as needed

Registration Pattern

Basic Registration

Copy// Use registerLazySingleton (NOT registerSingleton)
sl.registerLazySingleton<MyService>(() => MyService(
  dependencyService: sl<DependencyService>(),
));

With Dependencies

Copy// Register dependencies BEFORE dependents
sl.registerLazySingleton(() => DependencyService());
sl.registerLazySingleton(() => MyService(
  dependencyService: sl<DependencyService>(),
));

Check Before Registration

Copy// Check if already registered to avoid duplicates
if (!sl.isRegistered<MyService>()) {
  sl.registerLazySingleton<MyService>(() => MyService(
    dependencyService: sl<DependencyService>(),
  ));
}

With Documentation Comment

Copy// Register MyService (for specific purpose description)
sl.registerLazySingleton<MyService>(() => MyService(
  dependencyService: sl<DependencyService>(),
));

Service Constructor Pattern

Copyclass MyService {
  final DependencyService _dependencyService;
  final OptionalService? _optionalService;
  
  MyService({
    required DependencyService dependencyService,
    OptionalService? optionalService,
  })  : _dependencyService = dependencyService,
        _optionalService = optionalService;
}

Dependency Order Rules

1. Core services first - Register foundational services (StorageService, Logger, Database) before others
2. Dependencies before dependents - Always register dependencies before services that depend on them
3. Module separation - Register core services, then domain services, then feature services

Common Pitfalls

❌ Circular Dependency:

Copysl.registerLazySingleton(() => ServiceA(serviceB: sl<ServiceB>()));
sl.registerLazySingleton(() => ServiceB(serviceA: sl<ServiceA>())); // ERROR

❌ Wrong Order:

Copysl.registerLazySingleton(() => MyService(dep: sl<Dependency>())); // ERROR: Dependency not registered yet
sl.registerLazySingleton(() => Dependency());

❌ Wrong Lifecycle:

Copysl.registerFactory(() => MyService()); // BAD: Should be singleton

Reference

See existing registrations in:

• lib/injection_container_core.dart
• lib/injection_container.dart