Service creation in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a basic NestJS service class.

NestJS

import { Injectable } from '@nestjs/common';

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

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

AAppController

BMainService

CAppService

DHelloService

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'AppController' instead of a service name.

Forgetting to add the @Injectable() decorator.

The service class is usually named with 'Service' suffix, and 'AppService' is the common default name.

2fill in blank

medium

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

NestJS

import { Controller } from '@nestjs/common';
import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly [1]: AppService) {}
}

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

Aservice

BappService

Cappcontroller

DAppService

Attempts:

3 left

💡 Hint

Common Mistakes

Using the class name 'AppService' as the property name.

Using unrelated names like 'service' or 'appcontroller'.

The injected service is usually named in camelCase matching the class name, here 'appService'.

3fill in blank

hard

Fix the error in the service method to return a string.

NestJS

export class AppService {
  getHello(): [1] {
    return '123';
  }
}

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

Astring

Bnumber

Cboolean

Dvoid

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a number when the return type is string.

Using 'void' as return type but returning a value.

The method should return a string, so the return type must be 'string' and the return value a string.

4fill in blank

hard

Fill both blanks to create a service method that returns a greeting with a name parameter.

NestJS

export class AppService {
  getGreeting([1]: string): string {
    return `Hello, [2]!`;
  }
}

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

Aname

Busername

Duser

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the parameter and the template variable.

Forgetting to add the parameter type.

The parameter and the template variable must match, here both are 'name'.

5fill in blank

hard

Fill all three blanks to create a service that injects a repository and uses it in a method.

NestJS

import { Injectable } from '@nestjs/common';
import { [1] } from './user.repository';

@Injectable()
export class UserService {
  constructor(private readonly [2]: [1]) {}

  findAll() {
    return this.[2].findAllUsers();
  }
}

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

AUserRepository

BuserRepository

CUserService

DuserService

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing service and repository names.

Using inconsistent property names.

The repository class is 'UserRepository', injected as 'userRepository', which is used in the method.