MongoDB with Node.js Practice Questions with Solutions

Introduction

MongoDB with Node.js allows applications written in JavaScript to store, retrieve, update, and delete data in MongoDB. Node.js applications commonly connect to MongoDB using the official MongoDB Node.js driver. In this chapter, you will practice connecting Node.js to MongoDB, creating databases and collections, inserting documents, finding records, updating data, deleting documents, and closing the database connection. MongoDB with Node.js Practice questions with solutions to help you understand the concepts.

Q1. Install the MongoDB Node.js Driver

Problem Statement

Create a Node.js project and install the official MongoDB driver so that your application can communicate with MongoDB.

MongoDB Command / Query

Create a project:

mkdir mongodb-node-practice
cd mongodb-node-practice
npm init -y

Install the MongoDB driver:

npm install mongodb

Expected Output

The terminal should show a successful installation similar to:

added packages

Your project will contain:

mongodb-node-practice/
│
├── node_modules/
├── package.json
└── package-lock.json

Explanation

The mongodb npm package provides the official MongoDB Node.js driver.

Q2. Connect Node.js to MongoDB

Problem Statement

Write a Node.js program that connects to a MongoDB server running on the local computer.

MongoDB Command / Query

Create a file named app.js:

const { MongoClient } = require("mongodb");

const uri = "mongodb://127.0.0.1:27017";

const client = new MongoClient(uri);

async function main() {
    try {
        await client.connect();
        console.log("Connected to MongoDB");
    } catch (error) {
        console.error(error);
    } finally {
        await client.close();
    }
}

main();

Run:

node app.js

Expected Output

Connected to MongoDB

Explanation

MongoClient is used to connect a Node.js application to MongoDB.

The connection string:

mongodb://127.0.0.1:27017

points to a MongoDB server running locally on the default MongoDB port.

Q3. Select a Database and Collection

Problem Statement

Connect to MongoDB and access a database named school and a collection named students.

MongoDB Command / Query

const { MongoClient } = require("mongodb");

const uri = "mongodb://127.0.0.1:27017";

const client = new MongoClient(uri);

async function main() {
    try {
        await client.connect();

        const db = client.db("school");
        const students = db.collection("students");

        console.log("Database and collection selected");
    } catch (error) {
        console.error(error);
    } finally {
        await client.close();
    }
}

main();

Expected Output

Database and collection selected

Explanation

This code uses:

client.db("school")

to access the database and:

db.collection("students")

to access the collection.

The database and collection may be created when data is first written.

Q4. Insert One Document Using Node.js

Problem Statement

Insert one student document into the students collection using Node.js.

MongoDB Command / Query

const { MongoClient } = require("mongodb");

const uri = "mongodb://127.0.0.1:27017";

const client = new MongoClient(uri);

async function main() {
    try {
        await client.connect();

        const db = client.db("school");
        const students = db.collection("students");

        const result = await students.insertOne({
            name: "Rahul",
            age: 17,
            course: "Python"
        });

        console.log("Inserted ID:", result.insertedId);
    } catch (error) {
        console.error(error);
    } finally {
        await client.close();
    }
}

main();

Expected Output

Inserted ID: ObjectId("...")

Explanation

insertOne() inserts one document into the MongoDB collection.

MongoDB automatically generates an _id if you do not provide one.

Q5. Insert Multiple Documents Using Node.js

Problem Statement

Insert three students into the students collection using Node.js.

MongoDB Command / Query

const { MongoClient } = require("mongodb");

const uri = "mongodb://127.0.0.1:27017";
const client = new MongoClient(uri);

async function main() {
    try {
        await client.connect();

        const db = client.db("school");
        const students = db.collection("students");

        const result = await students.insertMany([
            {
                name: "Neha",
                age: 16,
                course: "Java"
            },
            {
                name: "Aman",
                age: 15,
                course: "C++"
            },
            {
                name: "Priya",
                age: 17,
                course: "JavaScript"
            }
        ]);

        console.log("Inserted:", result.insertedCount);
    } catch (error) {
        console.error(error);
    } finally {
        await client.close();
    }
}

main();

Expected Output

Inserted: 3

Explanation

insertMany() inserts multiple documents in one operation.

The insertedCount property tells you how many documents were successfully inserted.

Q6. Find Documents Using Node.js

Problem Statement

Retrieve all students whose course is Python.

MongoDB Command / Query

const { MongoClient } = require("mongodb");

const uri = "mongodb://127.0.0.1:27017";
const client = new MongoClient(uri);

async function main() {
    try {
        await client.connect();

        const db = client.db("school");
        const students = db.collection("students");

        const result = await students
            .find({ course: "Python" })
            .toArray();

        console.log(result);
    } catch (error) {
        console.error(error);
    } finally {
        await client.close();
    }
}

main();

Expected Output

[
    {
        _id: ObjectId("..."),
        name: "Rahul",
        age: 17,
        course: "Python"
    }
]

Explanation

find() returns a cursor in the MongoDB Node.js driver.

Using:

.toArray()

converts the cursor results into a JavaScript array.

Q7. Find One Document Using Node.js

Problem Statement

Find the student whose name is Rahul.

MongoDB Command / Query

const result = await students.findOne({
    name: "Rahul"
});

console.log(result);

Expected Output

{
    _id: ObjectId("..."),
    name: "Rahul",
    age: 17,
    course: "Python"
}

Explanation

findOne() returns one matching document or null if no matching document is found.

Unlike find(), you do not need to convert the result to an array.

Q8. Update a Document Using Node.js

Problem Statement

Update Rahul’s age from 17 to 18.

MongoDB Command / Query

const result = await students.updateOne(
    {
        name: "Rahul"
    },
    {
        $set: {
            age: 18
        }
    }
);

console.log("Matched:", result.matchedCount);
console.log("Modified:", result.modifiedCount);

Expected Output

Matched: 1
Modified: 1

Explanation

updateOne() updates the first document that matches the filter.

$set changes the value of the specified field without replacing the entire document.

Q9. Delete a Document Using Node.js

Problem Statement

Delete the student named Aman from the students collection.

MongoDB Command / Query

const result = await students.deleteOne({
    name: "Aman"
});

console.log("Deleted:", result.deletedCount);

Expected Output

Deleted: 1

Explanation

deleteOne() removes the first document matching the specified filter.

If no document matches, deletedCount will be 0.

Q10. Perform CRUD Operations in One Node.js Program

Problem Statement

Create a simple Node.js program that performs the basic CRUD operations:

Insert a student
Read the student
Update the student’s age
Delete the student

MongoDB Command / Query

const { MongoClient } = require("mongodb");

const uri = "mongodb://127.0.0.1:27017";
const client = new MongoClient(uri);

async function main() {
    try {
        await client.connect();

        const db = client.db("school");
        const students = db.collection("students");

        // CREATE
        const insertResult = await students.insertOne({
            name: "Ravi",
            age: 16,
            course: "Node.js"
        });

        console.log("Inserted:", insertResult.insertedId);

        // READ
        const student = await students.findOne({
            _id: insertResult.insertedId
        });

        console.log("Student:", student);

        // UPDATE
        const updateResult = await students.updateOne(
            {
                _id: insertResult.insertedId
            },
            {
                $set: {
                    age: 17
                }
            }
        );

        console.log("Updated:", updateResult.modifiedCount);

        // DELETE
        const deleteResult = await students.deleteOne({
            _id: insertResult.insertedId
        });

        console.log("Deleted:", deleteResult.deletedCount);

    } catch (error) {
        console.error(error);
    } finally {
        await client.close();
    }
}

main();

Expected Output

Inserted: ObjectId("...")
Student: {
  _id: ObjectId("..."),
  name: "Ravi",
  age: 16,
  course: "Node.js"
}
Updated: 1
Deleted: 1

Explanation

This example demonstrates the complete basic CRUD flow between Node.js and MongoDB:

Node.js
   ↓
MongoDB Driver
   ↓
MongoDB
   ↓
Database → Collection → Documents

The four main operations are:

Create → insertOne()
Read → find() / findOne()
Update → updateOne()
Delete → deleteOne()

Key Takeaways

Node.js can communicate with MongoDB using the official mongodb driver.
Install the driver with npm install mongodb.
MongoClient is used to establish the MongoDB connection.
client.db() accesses a database.
db.collection() accesses a collection.
insertOne() inserts one document.
insertMany() inserts multiple documents.
find() returns a cursor, which can be converted to an array using toArray().
findOne() returns one matching document.
updateOne() updates one matching document.
deleteOne() deletes one matching document.
async/await makes asynchronous MongoDB operations easier to read.
Always close the MongoDB client when your application no longer needs the connection.
Node.js + MongoDB is commonly used for building JavaScript backend applications.

FAQs

1. How does Node.js connect to MongoDB?

Node.js can connect to MongoDB using the official MongoDB Node.js driver and MongoClient.

2. Which npm package is used for MongoDB in Node.js?

The official package is called mongodb.

Install it with:

npm install mongodb

3. What is `MongoClient` in Node.js (MongoDB using Node.js)?

MongoClient is a class provided by the MongoDB Node.js driver that is used to connect an application to MongoDB.

4. How do you insert a document into MongoDB using Node.js?

Use insertOne():

await students.insertOne({
    name: "Rahul",
    age: 17
});

5. How do you retrieve MongoDB documents in Node.js?

Use find() for multiple documents:

const students = await collection.find({}).toArray();

For a single document, use:

const student = await collection.findOne({
    name: "Rahul"
});

6. How do you update a MongoDB document using Node.js?

Use updateOne() with an update operator such as $set:

await collection.updateOne(
    { name: "Rahul" },
    { $set: { age: 18 } }
);

7. Can Node.js perform all MongoDB CRUD operations?

Yes. The MongoDB Node.js driver provides methods for creating, reading, updating, and deleting documents, including insertOne(), find(), updateOne(), and deleteOne().

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

Rishabh Kumar

Introduction

Q1. Install the MongoDB Node.js Driver

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q2. Connect Node.js to MongoDB

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q3. Select a Database and Collection

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q4. Insert One Document Using Node.js

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q5. Insert Multiple Documents Using Node.js

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q6. Find Documents Using Node.js

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q7. Find One Document Using Node.js

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q8. Update a Document Using Node.js

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q9. Delete a Document Using Node.js

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Q10. Perform CRUD Operations in One Node.js Program

Problem Statement

MongoDB Command / Query

Expected Output

Explanation

Key Takeaways

FAQs

1. How does Node.js connect to MongoDB?

2. Which npm package is used for MongoDB in Node.js?

3. What is MongoClient in Node.js (MongoDB using Node.js)?

4. How do you insert a document into MongoDB using Node.js?

5. How do you retrieve MongoDB documents in Node.js?

6. How do you update a MongoDB document using Node.js?

7. Can Node.js perform all MongoDB CRUD operations?

Related Posts

3. What is `MongoClient` in Node.js (MongoDB using Node.js)?