Flutter Dependency Injection

Dependency Injection

Priority: P1 (HIGH)

Structure

core/injection/
├── injection.dart  # Initialization & setup
└── modules/        # Third-party dependency modules (Dio, Storage)

Implementation Workflow

1. Annotate classes — Use @injectable annotations; avoid manual registry calls.
2. Choose scope — Default to @LazySingleton for repositories, services, and data sources (init on demand).
3. Register BLoCs as factories — Use @injectable (Factory) for BLoCs to ensure state resets per instance. Never use @Singleton() for BLoCs.
4. Inject abstractions — Always register implementations as abstract interfaces (as: IService).
5. Register third-party deps — Use @module for external instances (Dio, Hive, SharedPreferences).
6. Prefer constructor injection — Use mandatory constructor parameters; injectable resolves them automatically.

Registration & Test Mock Examples

See implementation examples for module registration and test mock swap patterns.

Reference & Examples

For module configuration and initialization templates: See references/REFERENCE.md.

Anti-Patterns

• No Inline getIt Calls: Inject via constructor instead of calling GetIt in UI build()
• No @Singleton BLoCs: Always use @injectable (Factory) to ensure state resets
• No Concrete Class Injection: Always inject abstract interface (e.g., IOrderRepository)
• No Manual Registration: Use @injectable annotations instead of manual getIt.register calls in production code

Related Topics

layer-based-clean-architecture | testing

Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:

• Dependency Injection
• abstract interface

Remediation anchors

• Remediation anchors: factory registration, fresh CartBloc instance