deleteOne method in MongoDB - Mini Project: Build & Apply

Using the deleteOne Method in MongoDB

📖 Scenario: You are managing a small online bookstore database. You want to remove a specific book from the collection when it is no longer available.

🎯 Goal: Learn how to use the deleteOne method in MongoDB to remove a single document from a collection based on a condition.

📋 What You'll Learn

Create a collection named books with specific book documents

Define a filter to select the book to delete

Use the deleteOne method with the filter

Confirm the deletion by checking the collection

💡 Why This Matters

🌍 Real World

Deleting outdated or unavailable items from a database is common in inventory management, online stores, and content management systems.

💼 Career

Knowing how to safely remove data using deleteOne is essential for database administrators and backend developers to maintain clean and accurate data.

1

Create the books collection with initial documents

Create a variable called books that represents a MongoDB collection. Insert these exact documents into books: { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' }, { title: '1984', author: 'George Orwell' }, and { title: 'To Kill a Mockingbird', author: 'Harper Lee' }.

MongoDB

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

Need a hint?

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

2

Define a filter to select the book to delete

Create a variable called filter that selects the document where the title is exactly '1984'.

MongoDB

const books = db.collection('books');
await books.insertMany([
  { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' },
  { title: '1984', author: 'George Orwell' },
  { title: 'To Kill a Mockingbird', author: 'Harper Lee' }
]);

// Create a filter to find the book with title '1984'
// Your code here

Need a hint?

Use an object with title: '1984' to create the filter.

3

Use deleteOne to remove the selected book

Call deleteOne on the books collection using the filter variable to delete the document where the title is '1984'. Store the result in a variable called deleteResult.

MongoDB

const books = db.collection('books');
await books.insertMany([
  { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' },
  { title: '1984', author: 'George Orwell' },
  { title: 'To Kill a Mockingbird', author: 'Harper Lee' }
]);

const filter = { title: '1984' };

// Use deleteOne with the filter and save the result in deleteResult
// Your code here

Need a hint?

Use await books.deleteOne(filter) and assign it to deleteResult.

4

Confirm the deletion by counting remaining documents

Create a variable called remainingCount that stores the number of documents left in the books collection after deletion by using the countDocuments method.

MongoDB

const books = db.collection('books');
await books.insertMany([
  { title: 'The Great Gatsby', author: 'F. Scott Fitzgerald' },
  { title: '1984', author: 'George Orwell' },
  { title: 'To Kill a Mockingbird', author: 'Harper Lee' }
]);

const filter = { title: '1984' };

const deleteResult = await books.deleteOne(filter);

// Count the remaining documents in books and store in remainingCount
// Your code here

Need a hint?

Use await books.countDocuments() to get the number of documents left.