Decorator-based architecture in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a NestJS controller using the correct decorator.

NestJS

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

@[1]('cats')
export class CatsController {
  // controller methods
}

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

AService

BInjectable

CModule

DController

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Injectable instead of @Controller

Confusing @Module with @Controller

The @Controller decorator defines a controller class in NestJS.

2fill in blank

medium

Complete the code to create a GET route handler in a NestJS controller.

NestJS

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

@Controller('dogs')
export class DogsController {
  @[1]()
  findAll() {
    return 'This action returns all dogs';
  }
}

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ADelete

BPost

CGet

DPut

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Post instead of @Get for a GET route

Forgetting to import the decorator

The @Get() decorator defines a handler for HTTP GET requests.

3fill in blank

hard

Fix the error in the service class by adding the correct decorator.

NestJS

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

export class CatsService {
  getCats() {
    return ['cat1', 'cat2'];
  }
}

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

AInjectable

BController

CModule

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Controller on a service class

Not adding any decorator to the service

The @Injectable decorator marks the class as a provider that can be injected.

4fill in blank

hard

Fill both blanks to define a NestJS module with a controller and a provider.

NestJS

import { Module } from '@nestjs/common';
import { CatsController } from './cats.controller';
import { CatsService } from './cats.service';

@Module({
  controllers: [[1]],
  providers: [[2]],
})
export class CatsModule {}

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

ACatsController

BCatsService

CDogsController

DDogsService

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing controllers and providers

Using unrelated classes in the arrays

The controllers array should include the controller class, and the providers array should include the service class.

5fill in blank

hard

Fill all three blanks to create a route handler that accepts a dynamic parameter and injects a service.

NestJS

import { Controller, Get, Param, [1] } from '@nestjs/common';
import { [3] } from '@nestjs/common';

@[3]()
export class CatsService {
  [2](id) {
    return 'Cat ' + id;
  }
}

@Controller('cats')
export class CatsController {
  constructor(@[1]() private readonly catsService: CatsService) {}

  @Get(':id')
  getCat(@Param('id') id: string) {
    return this.catsService.[2](id);
  }
}

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AInjectable

BfindOne

CInject

DgetCats

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Injectable in the controller instead of the service

Calling a non-existent service method

Not importing the correct decorators

@Inject is used to inject dependencies manually, findOne is a typical service method to get one item, and @Injectable decorates the service class.