ai-sdlc-workflow: Skill for Cursor

NestJS Best Practices (Consolidated)

Use this skill for modules, controllers, services, auth, migrations, and API work. Tier 4 only: .cursor/skills/nestjs-skills/advanced/*.md

Module Structure (CRITICAL)

Organize by feature, not technical layer:

src/modules/{feature}/
├── dto/
├── entities/
├── {feature}.controller.ts
├── {feature}.service.ts
├── {feature}.repository.ts   # optional
├── {feature}.module.ts
└── index.ts

@Module({
  imports: [TypeOrmModule.forFeature([User])],
  controllers: [UsersController],
  providers: [UsersService, UsersRepository],
  exports: [UsersService], // export only what others need
})
export class UsersModule {}

• Avoid circular imports — extract shared providers to SharedModule
• One service = one responsibility; no god services
• Use repository pattern when DB logic needs mocking

Dependency Injection (CRITICAL)

• Constructor injection only — never service locator
• Use injection tokens for interfaces: @Inject(USER_REPO) private repo: UserRepository
• Default scope is singleton; use request scope only when needed

@Injectable()
export class UsersService {
  constructor(
    private readonly usersRepo: UsersRepository,
    private readonly logger: Logger,
  ) {}
}

Controllers & Services

• Controller: validate input, delegate to service, return DTO
• Service: business logic, transactions, domain rules
• Never put business logic in controllers

@Controller('users')
export class UsersController {
  constructor(private readonly usersService: UsersService) {}

  @Post()
  create(@Body() dto: CreateUserDto): Promise<UserResponseDto> {
    return this.usersService.create(dto);
  }
}

Input Validation & DTOs

• Validate at boundary with ValidationPipe globally
• Use class-validator + class-transformer on DTOs
• Separate create/update/response DTOs; never return entities directly

export class CreateUserDto {
  @IsEmail()
  email: string;

  @MinLength(8)
  password: string;
}