Single document atomicity in MongoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to update a single field atomically in a MongoDB document.

MongoDB

db.collection.updateOne({ _id: 1 }, { [1]: { score: 100 } })

Drag options to blanks, or click blank then click option'

A$push

B$inc

C$set

D$unset

Attempts:

3 left

💡 Hint

Common Mistakes

Using $inc when you want to set a specific value.

Using $push which is for arrays, not single fields.

The $set operator updates the value of a field atomically in a single document.

2fill in blank

medium

Complete the code to increment a numeric field atomically in a MongoDB document.

MongoDB

db.collection.updateOne({ _id: 2 }, { [1]: { visits: 1 } })

Drag options to blanks, or click blank then click option'

A$set

B$addToSet

C$push

D$inc

Attempts:

3 left

💡 Hint

Common Mistakes

Using $set which replaces the value instead of incrementing.

Using $push which is for arrays.

The $inc operator increments a numeric field atomically by the specified value.

3fill in blank

hard

Fix the error in the update command to atomically add a value to an array field without duplicates.

MongoDB

db.collection.updateOne({ _id: 3 }, { [1]: { tags: "mongodb" } })

Drag options to blanks, or click blank then click option'

A$push

B$addToSet

C$set

D$inc

Attempts:

3 left

💡 Hint

Common Mistakes

Using $push which can add duplicates.

Using $set which replaces the whole array.

The $addToSet operator adds a value to an array only if it does not already exist, ensuring atomicity.

4fill in blank

hard

Fill both blanks to atomically update multiple fields in a single document.

MongoDB

db.collection.updateOne({ _id: 4 }, { [1]: { score: 90, level: 5 } })

Drag options to blanks, or click blank then click option'

A$set

B$inc

C$unset

D$push

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing $set with $inc or other operators incorrectly.

Using $unset which removes fields instead of updating.

Using $set for both fields updates them atomically in a single document.

5fill in blank

hard

Fill all three blanks to atomically update a document: increment visits, add a tag uniquely, and set status.

MongoDB

db.collection.updateOne({ _id: 5 }, { [1]: { visits: 1 }, [2]: { tags: "new" }, [3]: { status: "active" } })

Drag options to blanks, or click blank then click option'

A$inc

B$addToSet

C$set

D$push

Attempts:

3 left

💡 Hint

Common Mistakes

Using $push instead of $addToSet causing duplicates.

Using $set to increment numbers which replaces values.

Use $inc to increment visits, $addToSet to add unique tags, and $set to update status atomically.