Module decorator and metadata in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @Module decorator in NestJS?

The @Module decorator defines a module in NestJS. It organizes related components like controllers, providers, and imports into a single unit, helping structure the app clearly.

beginner

Name the main metadata properties used inside the @Module decorator.

The main properties are: <br>• imports: other modules to include<br>• controllers: classes handling incoming requests<br>• providers: services or classes that provide functionality<br>• exports: providers made available to other modules

intermediate

How does the 'imports' property in @Module metadata work?

The 'imports' property lists other modules whose exported providers are needed in this module. It allows sharing functionality between modules.

intermediate

What happens if you forget to add a provider to the 'providers' array in a module?

NestJS will not recognize the provider as injectable in that module, causing errors when trying to use it in controllers or other providers.

intermediate

Explain the role of the 'exports' property in the @Module decorator.

The 'exports' property makes selected providers available to other modules that import this module. It helps share services across different parts of the app.

Which property in the @Module decorator lists the controllers of the module?

A controllers

B providers

C imports

D exports

The 'controllers' property holds the classes that handle incoming requests in the module.

What does the 'providers' array in a module contain?

A Other modules to import

B Controllers for handling requests

C Components for UI rendering

D Services and classes that provide functionality

The 'providers' array contains services or classes that provide business logic or functionality.

If you want to use a service from another module, which property should you use in your module?

A controllers

B providers

C imports

D exports

You add the other module to the 'imports' array to use its exported providers.

What is the effect of adding a provider to the 'exports' array?

A It makes the provider available to modules that import this module

B It hides the provider from other modules

C It registers the provider as a controller

D It deletes the provider

Adding a provider to 'exports' shares it with other modules that import this module.

Which decorator is used to define a module in NestJS?

A @Injectable

B @Module

C @Component

D @Controller

The '@Module' decorator defines a module and its metadata.

Describe how the @Module decorator organizes an application in NestJS.

Think about how a folder groups related files.

Explain the roles of 'imports' and 'exports' in the @Module metadata.

Consider how you borrow and lend things between friends.