Injectable decorator in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to make the service class injectable.

NestJS

import { [1] } from '@nestjs/common';

@[1]()
export class MyService {
  getHello(): string {
    return 'Hello World!';
  }
}

Drag options to blanks, or click blank then click option'

AController

BInjectable

CModule

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Controller or @Module instead of @Injectable.

Forgetting to import the decorator.

The @Injectable() decorator marks a class as a provider that can be injected into other classes.

2fill in blank

medium

Complete the code to inject the service into the controller constructor.

NestJS

import { Controller } from '@nestjs/common';
import { MyService } from './my.service';

@Controller()
export class MyController {
  constructor(private readonly [1]: MyService) {}

  getHello(): string {
    return this.myService.getHello();
  }
}

Drag options to blanks, or click blank then click option'

Aservice

BserviceInstance

CMyService

DmyService

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name 'MyService' as the variable name.

Using unrelated variable names.

The injected service is usually named with camelCase, matching the class name starting with lowercase.

3fill in blank

hard

Fix the error in the service decorator import statement.

NestJS

import { Injectable } from '@nestjs/[1]';

@Injectable()
export class UserService {}

Drag options to blanks, or click blank then click option'

Acommon

Bservices

Ccore

Dmodules

Attempts:

3 left

💡 Hint

Common Mistakes

Importing Injectable from '@nestjs/core' or other incorrect paths.

Misspelling the package name.

The Injectable decorator is imported from '@nestjs/common', not from other sub-packages.

4fill in blank

hard

Fill both blanks to create a provider and inject it into a module.

NestJS

import { Module, [1] } from '@nestjs/common';
import { AppService } from './app.service';

@Module({
  providers: [AppService],
  exports: [[2]],
})
export class AppModule {}

Drag options to blanks, or click blank then click option'

AInjectable

BAppService

CController

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using Controller or Service instead of Injectable in imports.

Exporting the wrong class or forgetting to export.

The Injectable decorator is imported to mark providers, and the AppService is exported from the module.

5fill in blank

hard

Fill all three blanks to define an injectable service with a method and inject it into a controller.

NestJS

import { [1] } from '@nestjs/common';

@[1]()
export class GreetingService {
  sayHello(): string {
    return 'Hello!';
  }
}

import { Controller } from '@nestjs/common';
import { GreetingService } from './greeting.service';

@Controller()
export class GreetingController {
  constructor(private readonly {{BLANK_3}}: GreetingService) {}

  greet(): string {
    return this.{{BLANK_3}}.sayHello();
  }
}

Drag options to blanks, or click blank then click option'

AInjectable

BgreetingService

CGreetingService

Dservice

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name 'GreetingService' as the injected variable name.

Forgetting to import Injectable.

The Injectable decorator is used twice: once for import and once for decorating the class. The injected property name is camelCase 'greetingService'.