Application lifecycle in NestJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to implement the OnModuleInit lifecycle hook in a NestJS service.

NestJS

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

@Injectable()
export class AppService implements [1] {
  onModuleInit() {
    console.log('Module initialized');
  }
}

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

AModuleInit

BOnInit

COnModuleInit

DInitModule

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent interface like OnInit or InitModule.

Forgetting to import the interface from '@nestjs/common'.

The OnModuleInit interface is used to hook into the module initialization lifecycle event in NestJS.

2fill in blank

medium

Complete the code to implement the OnApplicationBootstrap lifecycle hook in a NestJS service.

NestJS

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

@Injectable()
export class AppService implements [1] {
  onApplicationBootstrap() {
    console.log('Application bootstrap completed');
  }
}

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AOnModuleDestroy

BOnApplicationBootstrap

COnBootstrap

DOnAppStart

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing with OnModuleDestroy or other lifecycle hooks.

Using incorrect interface names like OnBootstrap.

The OnApplicationBootstrap interface allows running code after all modules have been initialized and the application is bootstrapped.

3fill in blank

hard

Fix the error in the code by completing the lifecycle hook interface for graceful shutdown.

NestJS

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

@Injectable()
export class AppService implements [1] {
  async onModuleDestroy() {
    console.log('Module is being destroyed');
  }
}

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AOnModuleDestroy

BOnDestroy

COnAppDestroy

DOnDestroyModule

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect interface names like OnDestroy or OnAppDestroy.

Not implementing the interface but defining the method.

The OnModuleDestroy interface is the correct lifecycle hook for cleanup when a module is destroyed.

4fill in blank

hard

Fill both blanks to implement the OnApplicationShutdown lifecycle hook and handle shutdown logic.

NestJS

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

@Injectable()
export class AppService implements [2] {
  onApplicationShutdown(signal?: string) {
    console.log(`Application shutting down due to: ${signal}`);
  }
}

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AOnApplicationShutdown

BOnShutdown

COnAppShutdown

DOnShutdownApplication

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for import and implementation.

Using incorrect interface names like OnShutdown or OnAppShutdown.

The OnApplicationShutdown interface is used to run code during application shutdown, such as cleanup tasks.

5fill in blank

hard

Fill all three blanks to implement OnModuleInit, OnApplicationBootstrap, and OnModuleDestroy lifecycle hooks in a NestJS service.

NestJS

import { Injectable, [1], [2], [3] } from '@nestjs/common';

@Injectable()
export class AppService implements [1], [2], [3] {
  onModuleInit() {
    console.log('Module initialized');
  }

  onApplicationBootstrap() {
    console.log('Application bootstrap completed');
  }

  onModuleDestroy() {
    console.log('Module destroyed');
  }
}

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

AOnModuleInit

BOnApplicationBootstrap

COnModuleDestroy

DOnApplicationShutdown

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up interface names or missing one of them.

Using OnApplicationShutdown instead of OnModuleDestroy for module destruction.

These three interfaces correspond to key lifecycle events: module initialization, application bootstrap, and module destruction.