$each modifier with $push in MongoDB - Mini Project: Build & Apply

$each modifier with $push in MongoDB

📖 Scenario: You are managing a MongoDB collection that stores information about books in a library. Each book document has a title and an array called genres that lists the genres the book belongs to.Sometimes, new genres need to be added to a book's genres array all at once.

🎯 Goal: Learn how to use the $push operator with the $each modifier to add multiple genres to the genres array of a book document in a single update operation.

📋 What You'll Learn

Create a collection called books with one book document.

Add a variable to hold the new genres to add.

Use $push with $each to add multiple genres to the genres array.

Update the book document to include the new genres.

💡 Why This Matters

🌍 Real World

In real-world applications, you often need to update array fields in database documents by adding multiple items at once, such as tags, categories, or genres.

💼 Career

Knowing how to efficiently update arrays in MongoDB using $push with $each is a common task for backend developers and database administrators working with NoSQL databases.

1

Create the initial books collection with one book document

Create a collection called books and insert one document with title set to 'The Great Adventure' and genres set to an array containing 'Adventure' and 'Fantasy'.

MongoDB

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

Need a hint?

Use db.books.insertOne() with a document containing title and genres fields.

2

Create a variable with new genres to add

Create a variable called newGenres and set it to an array containing 'Mystery' and 'Thriller'.

MongoDB

db.books.insertOne({ title: 'The Great Adventure', genres: ['Adventure', 'Fantasy'] })
// Create a variable called newGenres with ['Mystery', 'Thriller']
// Your code here

Need a hint?

Use const newGenres = ['Mystery', 'Thriller'] to create the array.

3

Use $push with $each to add multiple genres

Write an update query that uses db.books.updateOne() to find the document with title equal to 'The Great Adventure' and uses $push with $each to add all genres from the newGenres array to the genres array.

MongoDB

db.books.insertOne({ title: 'The Great Adventure', genres: ['Adventure', 'Fantasy'] })
const newGenres = ['Mystery', 'Thriller']
// Use updateOne with $push and $each to add newGenres to genres array
// Your code here

Need a hint?

Use db.books.updateOne() with a filter on title and an update using { $push: { genres: { $each: newGenres } } }.

4

Verify the update by querying the updated document

Write a query using db.books.findOne() to find the document with title equal to 'The Great Adventure' to confirm the genres array now includes 'Mystery' and 'Thriller'.

MongoDB

db.books.insertOne({ title: 'The Great Adventure', genres: ['Adventure', 'Fantasy'] })
const newGenres = ['Mystery', 'Thriller']
db.books.updateOne(
  { title: 'The Great Adventure' },
  { $push: { genres: { $each: newGenres } } }
)
// Query the updated document with findOne
// Your code here

Need a hint?

Use db.books.findOne({ title: 'The Great Adventure' }) to see the updated document.