Service creation in NestJS - Mini Project: Build & Apply

Service Creation in NestJS

📖 Scenario: You are building a simple NestJS application to manage a list of books in a library. You want to create a service that will hold the data and provide methods to access it.

🎯 Goal: Create a NestJS service called BooksService that stores a list of books and provides a method to get all books.

📋 What You'll Learn

Create a service class named BooksService

Add a private array property called books with three book titles as strings

Add a method called getAllBooks() that returns the books array

Export the service class properly

💡 Why This Matters

🌍 Real World

Services in NestJS hold business logic and data. Creating a service to manage books is like having a librarian who knows all the books and can share that info when asked.

💼 Career

Understanding how to create and use services is essential for backend development with NestJS, a popular framework for building scalable server applications.

1

Create the BooksService class with a books array

Create a class called BooksService and inside it, create a private property called books that is an array containing these exact strings: 'The Hobbit', '1984', 'Brave New World'.

NestJS

class BooksService {
  // Create a private books array with the given book titles
  // Your code here
}

Need a hint?

Remember to use private books = [...] inside the class.

2

Add the getAllBooks method

Inside the BooksService class, add a method called getAllBooks() that returns the books array.

NestJS

class BooksService {
  private books = ['The Hobbit', '1984', 'Brave New World'];

  // Add getAllBooks method that returns books array
  // Your code here
}

Need a hint?

The method should return this.books.

3

Add the @Injectable decorator

Import Injectable from @nestjs/common and add the @Injectable() decorator above the BooksService class.

NestJS

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

// Add @Injectable decorator here
class BooksService {
  private books = ['The Hobbit', '1984', 'Brave New World'];

  getAllBooks() {
    return this.books;
  }
}

Need a hint?

Use @Injectable() just before the class declaration.

4

Export the BooksService class

Add an export statement to export the BooksService class so it can be used in other parts of the application.

NestJS

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

@Injectable()
// Export the BooksService class
// Your code here
class BooksService {
  private books = ['The Hobbit', '1984', 'Brave New World'];

  getAllBooks() {
    return this.books;
  }
}

Need a hint?

Use export class BooksService instead of just class BooksService.