$push operator for adding to arrays in MongoDB - Mini Project: Build & Apply

$push Operator to Add Items to Arrays in MongoDB

📖 Scenario: You are managing a simple online bookstore database. Each book document has a title and an array of reviews. You want to add new reviews to the books as customers submit them.

🎯 Goal: Build a MongoDB update operation using the $push operator to add new review entries to the reviews array of a book document.

📋 What You'll Learn

Create a collection named books with one book document containing a title and an empty reviews array.

Define a new review object with user and comment fields.

Use the $push operator to add the new review to the reviews array of the book.

Complete the update command to modify the correct book document by its title.

💡 Why This Matters

🌍 Real World

Adding user-generated content like reviews or comments to documents is common in many applications such as e-commerce, blogs, and social media.

💼 Career

Understanding how to update array fields in MongoDB documents is essential for backend developers working with NoSQL databases.

1

Create the books collection with one book document

Create a collection called books and insert one document with title set to 'Learn MongoDB' and an empty array reviews.

MongoDB

// Insert the book document into the books collection
// Your code here

Need a hint?

Use insertOne to add a document with the specified fields.

2

Define a new review object

Create a variable called newReview that holds an object with user set to 'Alice' and comment set to 'Great book!'.

MongoDB

db.books.insertOne({ title: 'Learn MongoDB', reviews: [] })
// Define the newReview object below
// Your code here

Need a hint?

Use const newReview = { user: 'Alice', comment: 'Great book!' } to define the review.

3

Use $push to add the review to the book's reviews array

Write an update command using db.books.updateOne to find the book with title equal to 'Learn MongoDB' and use $push to add newReview to the reviews array.

MongoDB

db.books.insertOne({ title: 'Learn MongoDB', reviews: [] })
const newReview = { user: 'Alice', comment: 'Great book!' }
// Add the updateOne command to push newReview into reviews
// Your code here

Need a hint?

Use updateOne with a filter and {$push: { reviews: newReview }} to add the review.

4

Complete the update command with options

Add the option { upsert: false } as the third argument to updateOne to ensure no new document is created if the book is not found.

MongoDB

db.books.insertOne({ title: 'Learn MongoDB', reviews: [] })
const newReview = { user: 'Alice', comment: 'Great book!' }
db.books.updateOne({ title: 'Learn MongoDB' }, { $push: { reviews: newReview } })
// Add the options object with upsert: false
// Your code here

Need a hint?

Pass { upsert: false } as the third argument to updateOne.