Insert with nested documents in MongoDB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

Insert a document with nested address

Given the following insert command, what will be the content of the inserted document in the collection?

MongoDB

db.users.insertOne({name: "Alice", age: 30, address: {street: "123 Maple St", city: "Springfield", zip: "01101"}})

A {"name": "Alice", "age": 30, "address": {"street": "123 Maple St", "city": "Springfield"}}

B {"name": "Alice", "age": 30, "address": "123 Maple St, Springfield, 01101"}

C {"name": "Alice", "age": 30, "street": "123 Maple St", "city": "Springfield", "zip": "01101"}

D {"name": "Alice", "age": 30, "address": {"street": "123 Maple St", "city": "Springfield", "zip": "01101"}}

💡 Hint

Nested documents are stored as embedded objects inside the main document.

The insertOne command stores the nested 'address' as an embedded document with all its fields intact.

❓ query_result

intermediate

Insert with multiple nested levels

What will be the structure of the document after this insert?

MongoDB

db.orders.insertOne({orderId: 101, customer: {name: "Bob", contact: {email: "[e-mail]", phone: "123-4567"}}, items: [{product: "Pen", qty: 10}, {product: "Notebook", qty: 5}]})

A {"orderId": 101, "customer": {"name": "Bob", "contact": {"email": "[e-mail]", "phone": "123-4567"}}, "items": [{"product": "Pen", "qty": 10}, {"product": "Notebook", "qty": 5}]}

B {"orderId": 101, "customer": {"name": "Bob", "email": "[e-mail]", "phone": "123-4567"}, "items": [{"product": "Pen", "qty": 10}, {"product": "Notebook", "qty": 5}]}

C {"orderId": 101, "customer": "Bob", "contact": {"email": "[e-mail]", "phone": "123-4567"}, "items": [{"product": "Pen", "qty": 10}, {"product": "Notebook", "qty": 5}]}

D {"orderId": 101, "customer": {"name": "Bob", "contact": {"email": "[e-mail]"}}, "items": [{"product": "Pen", "qty": 10}, {"product": "Notebook", "qty": 5}]}

💡 Hint

Nested objects can have multiple levels and arrays can contain objects.

The 'customer' field contains a nested 'contact' document, and 'items' is an array of nested documents.

📝 Syntax

advanced

Identify the syntax error in nested document insert

Which option contains a syntax error that will prevent the document from being inserted?

MongoDB

db.products.insertOne({name: "Chair", specs: {color: "red", weight: 5, dimensions: {width: 40, height: 90}}})

A db.products.insertOne({name: "Chair", specs: {color: "red", weight: 5, dimensions: {width: 40, height: 90}}}})

B db.products.insertOne({name: "Chair", specs: {color: "red", weight: 5, dimensions: {width: 40, height: 90}}})

C db.products.insertOne({name: "Chair", specs: {color: "red", weight: 5, dimensions: {width: 40, height: 90}}

D db.products.insertOne({name: "Chair", specs: {color: "red", weight: 5, dimensions: {width: 40, height: 90}});

💡 Hint

Check for matching braces and parentheses.

Option C is missing the closing brace and parenthesis, causing a syntax error.

🔧 Debug

advanced

Why does this nested insert fail?

This insert command fails. What is the cause?

MongoDB

db.employees.insertOne({name: "Eve", details: {age: 28, skills: ["JavaScript", "MongoDB"], projects: {current: "Website", completed: 3}})

A Missing closing brace for the main document.

B Array syntax is incorrect inside 'skills'.

C Field names must be quoted with double quotes.

D MongoDB does not support nested documents.

💡 Hint

Count the opening and closing braces carefully.

The main document is missing a closing brace at the end, causing the insert to fail.

❓ optimization

expert

Optimizing nested document insert for large arrays

You want to insert a document with a large array of nested documents efficiently. Which approach is best?

A Insert the main document first, then update it multiple times to add array elements one by one.

B Insert the entire document with the large nested array in one insertOne command.

C Split the large array into smaller chunks and insert multiple documents instead of one.

D Use bulkWrite with multiple insertOne operations for each nested document inside the array.

💡 Hint

MongoDB handles nested arrays well if inserted in one document.

Inserting the entire nested array at once is more efficient than multiple updates or splitting into many documents.