Decorator-based architecture in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a decorator in NestJS?

A decorator in NestJS is a special function that adds metadata or behavior to classes, methods, or properties. It helps organize code by marking parts with extra information NestJS uses to build the app.

beginner

How does the @Controller() decorator work in NestJS?

The @Controller() decorator marks a class as a controller that handles incoming HTTP requests. It tells NestJS to group related routes inside this class.

beginner

What role do method decorators like @Get() or @Post() play in NestJS?

Method decorators like @Get() or @Post() define which HTTP method and route a class method should respond to. They connect URLs to specific functions.

intermediate

Why is decorator-based architecture helpful in NestJS?

It keeps code clean and easy to read by clearly showing what each part does. It also helps NestJS automatically build the app structure and handle requests without extra setup.

intermediate

Can you explain how dependency injection uses decorators in NestJS?

Decorators like @Injectable() mark classes as services that NestJS can create and share. Then, constructor parameters typed with classes let NestJS automatically provide those services where needed.

What does the @Injectable() decorator do in NestJS?

A Marks a class as a service that can be injected

B Defines a route handler

C Marks a class as a controller

D Creates a database connection

The @Injectable() decorator marks a class as a service that NestJS can inject into other classes.

Which decorator would you use to handle HTTP GET requests in NestJS?

A @Post()

B @Get()

C @Controller()

D @Injectable()

The @Get() decorator marks a method to handle HTTP GET requests.

What is the main purpose of decorators in NestJS architecture?

A To create database tables

B To write CSS styles

C To add metadata and organize code structure

D To run JavaScript in the browser

Decorators add metadata and help organize the code structure in NestJS.

How does NestJS know which class is a controller?

A By the class name

B By the file extension

C By the @Injectable() decorator

D By the @Controller() decorator

NestJS uses the @Controller() decorator to identify controller classes.

Which decorator helps NestJS inject dependencies automatically?

A @Injectable()

B @Post()

C @Controller()

D @Get()

The @Injectable() decorator marks classes for dependency injection.

Describe how decorators help organize a NestJS application.

Think about how NestJS uses special marks to know what each part does.

Explain the role of @Controller() and @Get() decorators in handling web requests.

Focus on how NestJS matches URLs to functions.