CRUD operations in NestJS - Mini Project: Build & Apply

CRUD Operations with NestJS

📖 Scenario: You are building a simple NestJS backend to manage a list of books in a library. Each book has an id, title, and author.This backend will allow users to create, read, update, and delete books.

🎯 Goal: Build a NestJS service that performs basic CRUD operations on an in-memory list of books.

📋 What You'll Learn

Create an initial array of books with exact entries

Add a variable to track the next book ID

Implement methods to create, read, update, and delete books

Export the service class with all CRUD methods

💡 Why This Matters

🌍 Real World

Backend services often need to manage data with create, read, update, and delete operations. This project shows how to do that simply with NestJS.

💼 Career

Understanding CRUD operations in NestJS is essential for backend developers building APIs and services.

1

Data Setup: Create initial books array

Create a variable called books that is an array containing these exact objects: { id: 1, title: '1984', author: 'George Orwell' } and { id: 2, title: 'Brave New World', author: 'Aldous Huxley' }.

NestJS

// Create the books array with two book objects
// Your code here

Need a hint?

Use const books = [ ... ] with two objects inside.

2

Configuration: Add nextId variable

Add a variable called nextId and set it to 3 to track the next book ID.

NestJS

const books = [
  { id: 1, title: '1984', author: 'George Orwell' },
  { id: 2, title: 'Brave New World', author: 'Aldous Huxley' }
];

// Add nextId variable here
// Your code here

Need a hint?

Use let nextId = 3; to allow incrementing later.

3

Core Logic: Implement CRUD methods in BooksService

Create a class called BooksService with these methods: findAll() that returns books, findOne(id) that returns the book with matching id, create(title, author) that adds a new book with a new id, update(id, title, author) that updates the matching book, and remove(id) that deletes the book with the given id. Use the variables books and nextId inside the class.

NestJS

const books = [
  { id: 1, title: '1984', author: 'George Orwell' },
  { id: 2, title: 'Brave New World', author: 'Aldous Huxley' }
];

let nextId = 3;

// Create BooksService class with CRUD methods
// Your code here

Need a hint?

Define a class with methods using the books array and nextId variable.

4

Completion: Export the BooksService class

Add export default BooksService; at the end of the file to export the service class.

NestJS

const books = [
  { id: 1, title: '1984', author: 'George Orwell' },
  { id: 2, title: 'Brave New World', author: 'Aldous Huxley' }
];

let nextId = 3;

class BooksService {
  findAll() {
    return books;
  }

  findOne(id) {
    return books.find(book => book.id === id);
  }

  create(title, author) {
    const newBook = { id: nextId++, title, author };
    books.push(newBook);
    return newBook;
  }

  update(id, title, author) {
    const book = books.find(book => book.id === id);
    if (book) {
      book.title = title;
      book.author = author;
    }
    return book;
  }

  remove(id) {
    const index = books.findIndex(book => book.id === id);
    if (index !== -1) {
      books.splice(index, 1);
      return true;
    }
    return false;
  }
}

// Export the BooksService class
// Your code here

Need a hint?

Use export default BooksService; at the end.