Modules & ProvidersBeginner
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typescriptHow does NestJS leverage Dependency Injection and Modules for enterprise architecture?
Explanation & Concept
NestJS is a progressive Node.js framework built with TypeScript that organizes code into **Modules**, **Controllers**, and **Providers** (Services) inspired by Angular.
NestJS uses an Inversion of Control (IoC) container with constructor-based Dependency Injection to manage service lifecycles and promote testability.
Code Example
typescript
import { Injectable, Module, Controller, Get } from "@nestjs/common";
@Injectable()
export class UserService {
getUsers() {
return [{ id: 1, name: "Jordan" }];
}
}
@Controller("users")
export class UserController {
constructor(private readonly userService: UserService) {} // Dependency Injection!
@Get()
findAll() {
return this.userService.getUsers();
}
}
@Module({
controllers: [UserController],
providers: [UserService],
})
export class UserModule {}How It Works & Key Takeaways
By injecting `UserService` into `UserController`, unit testing becomes trivial: simply pass a mock service into the controller constructor.
Mock Test · 1 Questions · Optional
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Beginner3 questions