lcbp3/.agents/skills/nestjs-best-practices/rules/arch-feature-modules.md

title, impact, impactDescription, tags

title	impact	impactDescription	tags
Organize by Feature Modules	CRITICAL	3-5x faster onboarding and development	architecture, modules, organization

Organize by Feature Modules

Organize your application into feature modules that encapsulate related functionality. Each feature module should be self-contained with its own controllers, services, entities, and DTOs. Avoid organizing by technical layer (all controllers together, all services together). This enables 3-5x faster onboarding and feature development.

Incorrect (technical layer organization):

// Technical layer organization (anti-pattern)
src/
├── controllers/
│   ├── users.controller.ts
│   ├── orders.controller.ts
│   └── products.controller.ts
├── services/
│   ├── users.service.ts
│   ├── orders.service.ts
│   └── products.service.ts
├── entities/
│   ├── user.entity.ts
│   ├── order.entity.ts
│   └── product.entity.ts
└── app.module.ts  // Imports everything directly

Correct (feature module organization):

// Feature module organization
src/
├── users/
│   ├── dto/
│   │   ├── create-user.dto.ts
│   │   └── update-user.dto.ts
│   ├── entities/
│   │   └── user.entity.ts
│   ├── users.controller.ts
│   ├── users.service.ts
│   ├── users.repository.ts
│   └── users.module.ts
├── orders/
│   ├── dto/
│   ├── entities/
│   ├── orders.controller.ts
│   ├── orders.service.ts
│   └── orders.module.ts
├── shared/
│   ├── guards/
│   ├── interceptors/
│   ├── filters/
│   └── shared.module.ts
└── app.module.ts

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

// app.module.ts
@Module({
  imports: [
    ConfigModule.forRoot(),
    TypeOrmModule.forRoot(),
    UsersModule,
    OrdersModule,
    SharedModule,
  ],
})
export class AppModule {}

Reference: NestJS Modules