Soft delete pattern in MongoDB - Mini Project: Build & Apply

Soft Delete Pattern in MongoDB

📖 Scenario: You are managing a user database for a web application. Instead of permanently deleting user records, you want to mark them as deleted so you can restore them later if needed.

🎯 Goal: Build a MongoDB collection with a soft delete pattern by adding a deleted field to user documents and write queries to filter out deleted users.

📋 What You'll Learn

Create a users collection with sample user documents

Add a deleted field to each user document to mark soft deletion

Write a query to find only users who are not deleted

Write a query to mark a user as deleted by setting deleted to true

💡 Why This Matters

🌍 Real World

Soft delete is used in many applications to avoid losing data permanently and to allow recovery of deleted records.

💼 Career

Understanding soft delete patterns is important for database management roles and backend development jobs where data integrity and recovery are critical.

1

Create the users collection with sample data

Create a users collection with these exact documents: { _id: 1, name: "Alice", deleted: false }, { _id: 2, name: "Bob", deleted: false }, and { _id: 3, name: "Charlie", deleted: false }.

MongoDB

// Insert the three user documents into the users collection
// Your code here

Need a hint?

Use db.users.insertMany() to add multiple documents at once.

2

Add a helper variable for the soft delete filter

Create a variable called activeUsersFilter and set it to { deleted: false } to select only users who are not deleted.

MongoDB

db.users.insertMany([
  { _id: 1, name: "Alice", deleted: false },
  { _id: 2, name: "Bob", deleted: false },
  { _id: 3, name: "Charlie", deleted: false }
])

// Create a filter variable to find users where deleted is false
// Your code here

Need a hint?

Use const activeUsersFilter = { deleted: false } to create the filter.

3

Write a query to find all active (not deleted) users

Write a query using db.users.find() with the filter variable activeUsersFilter to find all users where deleted is false.

MongoDB

db.users.insertMany([
  { _id: 1, name: "Alice", deleted: false },
  { _id: 2, name: "Bob", deleted: false },
  { _id: 3, name: "Charlie", deleted: false }
])

const activeUsersFilter = { deleted: false }

// Write a query to find all users where deleted is false
// Your code here

Need a hint?

Use db.users.find(activeUsersFilter) to get active users.

4

Mark a user as deleted using an update query

Write an update query using db.users.updateOne() to set deleted to true for the user with _id equal to 2.

MongoDB

db.users.insertMany([
  { _id: 1, name: "Alice", deleted: false },
  { _id: 2, name: "Bob", deleted: false },
  { _id: 3, name: "Charlie", deleted: false }
])

const activeUsersFilter = { deleted: false }

const activeUsers = db.users.find(activeUsersFilter)

// Update the user with _id 2 to set deleted to true
// Your code here

Need a hint?

Use db.users.updateOne({ _id: 2 }, { $set: { deleted: true } }) to mark the user as deleted.