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Designs NestJS application services as use-case classes that orchestrate domain logic and ports without leaking the framework. Use when creating new use cases, refactoring services that mix HTTP/DB/domain, or moving from anemic services to OOP.
| name | designing-nestjs-services |
| description | Designs NestJS application services as use-case classes that orchestrate domain logic and ports without leaking the framework. Use when creating new use cases, refactoring services that mix HTTP/DB/domain, or moving from anemic services to OOP. |
| license | MIT |
@Injectable() in domain)Result<T,E> from use-cases, don't throw for expected failures@Injectable()
export class CreateUserUseCase {
constructor(
@Inject('UserRepository') private readonly repo: UserRepository,
private readonly hasher: PasswordHasher
) {}
async execute(dto: CreateUserDto): Promise<Result<User, AppError>> {
const existing = await this.repo.findByEmail(dto.email);
if (existing) return err(new ConflictError(`User ${dto.email} already exists`));
const user = User.create(dto.id, Email.create(dto.email));
await this.repo.save(user);
return ok(user);
}
}
// Single responsibility use-case
@Injectable()
export class SubmitOrderUseCase {
constructor(
@Inject('OrderRepository') private repo: OrderRepository,
private paymentService: PaymentService
) {}
async execute(orderId: string): Promise<Result<Order, AppError>> { ... }
}
// ❌ Anemic service with many methods
@Injectable()
export class UserService {
create() { ... }
update() { ... }
delete() { ... }
// Mixed responsibilities
}
// ❌ Framework leaking into application
import { InjectRepository } from '@nestjs/typeorm'; // Should be in infra
Result<T,E>See reference/service-patterns.md for full patterns.
Defines the rule base every skill in this pack obeys: file layout, frontmatter, vocabulary, OOP/typing/decoupling axioms, and anti-patterns. Load FIRST before authoring or applying any other skill in this pack.
Designs NestJS feature modules with clean dependency boundaries, provider scopes, and dynamic modules. Use when adding a new feature module, splitting a monolithic AppModule, or fixing tangled imports between modules.
Builds thin NestJS controllers that parse input, invoke a single use case, and map the Result to ApiResponse<T>. Use when adding HTTP endpoints, refactoring fat controllers, or applying API versioning.
Prepares a NestJS service for production: graceful shutdown, health/readiness, structured logs, config, Dockerfile, CI gates, and rollout safety. Use when promoting a service to staging/production or auditing readiness.
Maps internal AppError hierarchy to HTTP responses through a single global exception filter and a Result-to-HttpException helper. Use when adding new error types, fixing inconsistent error responses, or removing scattered try/catch in controllers.
Implements the Repository pattern with TypeORM in NestJS so domain entities stay framework-free, ORM models live in infrastructure, and transactions are explicit. Use when adding persistence, refactoring leaky ORM usage, or handling transactions across aggregates.