findOne method in MongoDB - Mini Project: Build & Apply

Using the MongoDB findOne Method

📖 Scenario: You are managing a small library database. You want to find details about a specific book by its title.

🎯 Goal: Build a MongoDB query using the findOne method to retrieve a single book document by its title.

📋 What You'll Learn

Create a collection named books with specific book documents

Define a query filter to find a book by its exact title

Use the findOne method with the filter

Return the found book document

💡 Why This Matters

🌍 Real World

Finding a single record in a database is common in apps like libraries, stores, or user profiles.

💼 Career

Knowing how to use findOne helps you retrieve specific data efficiently in backend development and database management.

1

Create the books collection with sample data

Create a variable called books that represents a MongoDB collection. Insert these exact documents into books: { title: 'The Hobbit', author: 'J.R.R. Tolkien', year: 1937 }, { title: '1984', author: 'George Orwell', year: 1949 }, and { title: 'To Kill a Mockingbird', author: 'Harper Lee', year: 1960 }.

MongoDB

// Create the books collection and insert the documents
// Your code here

Need a hint?

Use db.collection('books') to get the collection. Use insertMany to add multiple documents.

2

Define a filter to find a book by title

Create a variable called filter and set it to an object that finds the book with the title exactly equal to '1984'.

MongoDB

const books = db.collection('books');

await books.insertMany([
  { title: 'The Hobbit', author: 'J.R.R. Tolkien', year: 1937 },
  { title: '1984', author: 'George Orwell', year: 1949 },
  { title: 'To Kill a Mockingbird', author: 'Harper Lee', year: 1960 }
]);

// Create the filter object to find the book titled '1984'
// Your code here

Need a hint?

The filter is an object with the key title and value '1984'.

3

Use findOne to get the book document

Create a variable called book and assign it the result of calling books.findOne(filter).

MongoDB

const books = db.collection('books');

await books.insertMany([
  { title: 'The Hobbit', author: 'J.R.R. Tolkien', year: 1937 },
  { title: '1984', author: 'George Orwell', year: 1949 },
  { title: 'To Kill a Mockingbird', author: 'Harper Lee', year: 1960 }
]);

const filter = { title: '1984' };

// Use findOne with the filter to get the book document
// Your code here

Need a hint?

Use await books.findOne(filter) to get the single matching document.

4

Complete the query by exporting the found book

Add a line to export the variable book using module.exports = book;.

MongoDB

const books = db.collection('books');

await books.insertMany([
  { title: 'The Hobbit', author: 'J.R.R. Tolkien', year: 1937 },
  { title: '1984', author: 'George Orwell', year: 1949 },
  { title: 'To Kill a Mockingbird', author: 'Harper Lee', year: 1960 }
]);

const filter = { title: '1984' };

const book = await books.findOne(filter);

// Export the found book
// Your code here

Need a hint?

Use module.exports = book; to export the result.