How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/j4flmao/agent_skills_nodejs_nestjs --skill designing-nestjs-servicesBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Designing NestJS Services
When to use
- Creating new use cases
- Refactoring services that mix HTTP/DB/domain
- Moving from anemic services to OOP
Core rules
- Application services are use-case classes, one per business intent
- Services orchestrate domain + ports, no framework imports (no
@Injectable()in domain) - Return
Result<T,E>from use-cases, don't throw for expected failures - Dependencies injected via constructor
- No HTTP/ORM imports in application services
Reference shape (TypeScript)
Use-Case Class
typescript
@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);
}
}Examples — Do
typescript
// 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>> { ... }
}Examples — Don't
typescript
// ❌ 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 infraChecklist
- [ ] Use-cases are single-responsibility classes
- [ ] Return
Result<T,E> - [ ] No framework imports in application layer
- [ ] Dependencies injected via constructor
See reference/service-patterns.md for full patterns.
