NestJS Architecture · NestJS Introduction in NestJS | NestJS

NestJS Architecture

Inspired by Angular and Spring

NestJS borrows ideas from Angular (modules, decorators, dependency injection) and Spring Boot (controllers, services, layered architecture). If you know Spring, NestJS will feel familiar.

NestJS	Spring Boot equivalent	Job
`@Module()`	`@Configuration` / package	Group related code
`@Controller()`	`@RestController`	Handle HTTP requests
`@Injectable()` service	`@Service`	Business logic
Repository (TypeORM/Prisma)	`JpaRepository`	Database access
Guard	Spring Security filter	Allow or deny a request
Pipe	Bean Validation	Validate and convert input

The Three Building Blocks

AppModule (root)
                 /             \
        ProductsModule      OrdersModule        <- modules group features
           |      \            |      \
 ProductsController  ProductsService ...        <- controllers: HTTP layer
                       |                           providers: business logic
                 ProductsRepository             <- data access

Request:  client --> Controller --> Service --> Repository --> Database

Module: a box that groups a feature (products, orders, users).
Controller: receives a request and returns a response. It should be thin.
Provider (usually a service): does the real work. NestJS creates it and injects it wherever it is needed.