Shared modules in NestJS - Mini Project: Build & Apply

Creating and Using Shared Modules in NestJS

📖 Scenario: You are building a NestJS application that needs to share a simple service across multiple modules. To avoid repeating code, you will create a shared module that exports this service so other modules can use it easily.

🎯 Goal: Build a shared module in NestJS that provides a LoggerService. Then import this shared module into another module to use the LoggerService.

📋 What You'll Learn

Create a LoggerService class with a method log(message: string) that logs messages.

Create a SharedModule that provides and exports LoggerService.

Create a FeatureModule that imports SharedModule.

Inject LoggerService into a service inside FeatureModule and use its log method.

💡 Why This Matters

🌍 Real World

Shared modules are common in real NestJS apps to provide reusable services like logging, configuration, or database access across many parts of the app.

💼 Career

Understanding shared modules is essential for building scalable and maintainable backend applications with NestJS, a popular framework used in many companies.

1

Create the LoggerService

Create a class called LoggerService with a method log(message: string) that logs the message to the console using console.log.

NestJS

# Create LoggerService class with log method
# Your code here

Need a hint?

Use console.log inside the log method to print the message.

2

Create SharedModule that provides and exports LoggerService

Create a NestJS module called SharedModule that provides and exports the LoggerService. Use the @Module decorator with providers and exports arrays containing LoggerService.

NestJS

export class LoggerService {
  log(message: string) {
    console.log(message);
  }
}

// Create SharedModule with @Module decorator
// Your code here

Need a hint?

Use @Module decorator from @nestjs/common and include LoggerService in both providers and exports.

3

Create FeatureModule that imports SharedModule

Create a NestJS module called FeatureModule that imports the SharedModule. Use the @Module decorator with an imports array containing SharedModule.

NestJS

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

export class LoggerService {
  log(message: string) {
    console.log(message);
  }
}

@Module({
  providers: [LoggerService],
  exports: [LoggerService]
})
export class SharedModule {}

// Create FeatureModule that imports SharedModule
// Your code here

Need a hint?

Use @Module decorator and add SharedModule to the imports array.

4

Inject LoggerService into a service in FeatureModule and use it

Create a service class called FeatureService inside FeatureModule. Inject LoggerService in its constructor and call this.logger.log('FeatureService initialized') inside the constructor.

NestJS

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

export class LoggerService {
  log(message: string) {
    console.log(message);
  }
}

@Module({
  providers: [LoggerService],
  exports: [LoggerService]
})
export class SharedModule {}

@Module({
  imports: [SharedModule]
})
export class FeatureModule {}

// Create FeatureService that injects LoggerService and logs a message
// Your code here

Need a hint?

Use @Injectable() on FeatureService, inject LoggerService in the constructor, and call log method.