Decorator-based architecture in NestJS - Mini Project: Build & Apply

Building a Simple Service with Decorator-based Architecture in NestJS

📖 Scenario: You are creating a small NestJS service that manages a list of books. You will use decorators to define a service class and a method that returns the list of books.

🎯 Goal: Build a NestJS service class called BooksService using the @Injectable() decorator. Inside it, create a method getBooks() that returns an array of book titles.

📋 What You'll Learn

Create a class named BooksService.

Use the @Injectable() decorator on the BooksService class.

Inside BooksService, create a method called getBooks().

The getBooks() method should return an array of strings: ["The Hobbit", "1984", "Clean Code"].

💡 Why This Matters

🌍 Real World

Services in NestJS are used to organize business logic and data access. Using decorators like @Injectable() helps NestJS manage dependencies automatically.

💼 Career

Understanding decorator-based architecture in NestJS is essential for backend development roles using this popular framework. It helps build clean, maintainable, and testable server-side applications.

1

Create the BooksService class

Create a class called BooksService.

NestJS

# Create a class called BooksService
# Your code here

Need a hint?

Use the class keyword followed by BooksService and curly braces.

2

Add the @Injectable() decorator

Add the @Injectable() decorator above the BooksService class. Also, import Injectable from @nestjs/common.

NestJS

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

// Add @Injectable() decorator below
export class BooksService {
}
# Your code here

Need a hint?

Place @Injectable() right before the class declaration.

3

Create the getBooks() method

Inside the BooksService class, create a method called getBooks() that returns the array ["The Hobbit", "1984", "Clean Code"].

NestJS

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

@Injectable()
export class BooksService {
    // Create getBooks() method here
    # Your code here
}

Need a hint?

Define a method named getBooks() inside the class that returns the exact array.

4

Export the BooksService class

Ensure the BooksService class is exported using the export keyword so it can be used in other parts of the application.

NestJS

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

// Make sure BooksService is exported
# Your code here

Need a hint?

The class should already be exported with the export keyword before class.