Dependency Injection
Register providers by module and keep framework wiring separate from business logic.
Provider registration
Dependency injection connects interfaces to concrete providers during application bootstrap. Each module should register only the dependencies required by its feature.
type UserModule struct {
Controller *UserController
Service *UserService
}
Constructor injection
Prefer constructor injection because it makes dependencies visible and keeps objects valid after creation.
func NewUserService(repository UserRepository) *UserService {
return &UserService{repository: repository}
}
Provider lifetime
Common lifetimes include:
- singleton for stateless services, database pools, and clients;
- request scoped for request-specific state;
- transient for objects that must be recreated for every resolution.
Circular dependencies
Circular dependencies usually indicate that feature boundaries are unclear. Extract shared behavior into a smaller service or introduce an event boundary instead of relying on container workarounds.