$set operator for setting fields in MongoDB - Mini Project: Build & Apply

$set Operator to Update User Profiles

📖 Scenario: You are managing a user database for a small online community. Each user has a profile stored as a document in a MongoDB collection called users. You want to update user profiles by changing or adding specific fields without replacing the entire document.

🎯 Goal: Learn how to use the MongoDB $set operator to update specific fields in user documents.

📋 What You'll Learn

Create a users collection with three user documents having fields _id, name, and age.

Define a filter to select a user by name.

Use the $set operator to update the age field of the selected user.

Add a new field email to the selected user using $set.

💡 Why This Matters

🌍 Real World

Updating user profiles is a common task in web applications where user information changes over time. Using the <code>$set</code> operator lets you change only the needed fields without affecting others.

💼 Career

Understanding how to update documents efficiently in MongoDB is essential for backend developers and database administrators working with NoSQL databases.

1

Create the users collection with initial user documents

Create a variable called users that is a list of three documents. Each document should have the exact fields and values: { _id: 1, name: "Alice", age: 25 }, { _id: 2, name: "Bob", age: 30 }, and { _id: 3, name: "Charlie", age: 35 }.

MongoDB

const users = [
  // Your code here
];

Need a hint?

Use an array with three objects. Each object must have _id, name, and age fields exactly as shown.

2

Define a filter to select the user named "Bob"

Create a variable called filter that is a document with the exact field name set to "Bob".

MongoDB

const users = [
  { _id: 1, name: "Alice", age: 25 },
  { _id: 2, name: "Bob", age: 30 },
  { _id: 3, name: "Charlie", age: 35 }
];

const filter = { /* Your code here */ };

Need a hint?

The filter should be an object with name set to "Bob".

3

Use the $set operator to update Bob's age to 31

Create a variable called update that uses the $set operator to set the age field to 31.

MongoDB

const users = [
  { _id: 1, name: "Alice", age: 25 },
  { _id: 2, name: "Bob", age: 30 },
  { _id: 3, name: "Charlie", age: 35 }
];

const filter = { name: "Bob" };

const update = { /* Your code here */ };

Need a hint?

Use $set with an object that sets age to 31.

4

Add a new field email to Bob's profile using $set

Extend the update variable to also set the email field to "[e-mail]" using the $set operator.

MongoDB

const users = [
  { _id: 1, name: "Alice", age: 25 },
  { _id: 2, name: "Bob", age: 30 },
  { _id: 3, name: "Charlie", age: 35 }
];

const filter = { name: "Bob" };

const update = { $set: { age: 31 /* Your code here */ } };

Need a hint?

Add email: "[e-mail]" inside the $set object.