Provider scope (default, request, transient) in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the provider scope to default (singleton).

NestJS

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

@Injectable({ scope: [1] })
export class MyService {}

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

AScope.DEFAULT

BScope.REQUEST

CScope.TRANSIENT

DScope.SINGLETON

Attempts:

3 left

💡 Hint

Common Mistakes

Using Scope.REQUEST or Scope.TRANSIENT when singleton is needed.

Using a non-existent Scope.SINGLETON value.

The default provider scope in NestJS is Scope.DEFAULT, which means the provider is a singleton.

2fill in blank

medium

Complete the code to set the provider scope to request-scoped.

NestJS

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

@Injectable({ scope: [1] })
export class RequestService {}

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AScope.REQUEST

BScope.TRANSIENT

CScope.DEFAULT

DScope.SINGLETON

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing request scope with transient or default scopes.

Using Scope.SINGLETON which does not exist.

Request scope means a new instance is created for each incoming request.

3fill in blank

hard

Fix the error in the provider scope declaration to make it transient.

NestJS

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

@Injectable({ scope: [1] })
export class TransientService {}

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AScope.DEFAULT

BScope.REQUEST

CScope.TRANSIENT

DScope.SINGLETON

Attempts:

3 left

💡 Hint

Common Mistakes

Using Scope.REQUEST instead of Scope.TRANSIENT.

Using Scope.DEFAULT which is singleton.

Transient scope means a new instance is created every time the provider is injected.

4fill in blank

hard

Fill both blanks to create a request-scoped provider and inject it into a controller.

NestJS

import { Injectable, Scope, Controller, Get } from '@nestjs/common';

@Injectable({ scope: [1] })
export class UserService {
  getUser() {
    return 'User Data';
  }
}

@Controller('users')
export class UserController {
  constructor(private readonly userService: [2]) {}

  @Get()
  getUser() {
    return this.userService.getUser();
  }
}

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AScope.REQUEST

BUserService

CScope.TRANSIENT

DUserController

Attempts:

3 left

💡 Hint

Common Mistakes

Using the controller class as the injected type.

Setting the wrong scope for the provider.

The provider is set to request scope with Scope.REQUEST. The controller injects the UserService to use its methods.

5fill in blank

hard

Fill all three blanks to create a transient provider, inject it, and call its method in a controller.

NestJS

import { Injectable, Scope, Controller, Get } from '@nestjs/common';

@Injectable({ scope: [1] })
export class LoggerService {
  log(message: string) {
    return `Log: ${message}`;
  }
}

@Controller('logs')
export class LogController {
  constructor(private readonly logger: [2]) {}

  @Get()
  getLog() {
    return this.logger.[3]('Hello');
  }
}

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

AScope.TRANSIENT

BLoggerService

Clog

DScope.REQUEST

Attempts:

3 left

💡 Hint

Common Mistakes

Using request scope instead of transient.

Calling a non-existent method on the provider.

The provider is transient scoped with Scope.TRANSIENT. The controller injects LoggerService and calls its log method.