Transactions vs atomic document writes in MongoDB - Interactive 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 }, { $set: { status: [1] } })

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A"active"

Bactive

Cstatus

D{ active }

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around string values.

Using variable names without quotes.

In MongoDB, string values must be in quotes. So to set the field status to the string "active", you need quotes.

2fill in blank

medium

Complete the code to start a transaction session in MongoDB.

MongoDB

const session = client.startSession();
session.[1]();

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AbeginTransaction

BinitTransaction

CopenTransaction

DstartTransaction

Attempts:

3 left

💡 Hint

Common Mistakes

Using beginTransaction() which is not a MongoDB method.

Using incorrect method names that do not exist.

The correct method to start a transaction in a MongoDB session is startTransaction().

3fill in blank

hard

Fix the error in the transaction commit code.

MongoDB

await session.[1]();

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AcommitTransaction

Bcommit

CcommitTxn

DendTransaction

Attempts:

3 left

💡 Hint

Common Mistakes

Using commit() which does not exist in MongoDB sessions.

Using incorrect method names like commitTxn().

The correct method to commit a transaction in MongoDB is commitTransaction().

4fill in blank

hard

Fill both blanks to update two fields atomically inside a transaction.

MongoDB

await collection.updateOne({ _id: 1 }, { $set: { status: [1], count: [2] } }, { session });

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A"completed"

B42

C"pending"

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Putting numbers in quotes.

Forgetting quotes around string values.

Inside a transaction, you can update multiple fields atomically. Here, status is set to the string "completed" and count to the number 42.

5fill in blank

hard

Fill all three blanks to correctly start a transaction, update a document, and commit the transaction.

MongoDB

const session = client.startSession();
try {
  session.[1]();
  await collection.updateOne({ _id: 2 }, { $set: { processed: [2] } }, { session });
  await session.[3]();
} finally {
  await session.endSession();
}

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AstartTransaction

Btrue

CcommitTransaction

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using false instead of true for the processed field.

Using wrong method names for starting or committing transactions.

This code starts a transaction with startTransaction(), updates the processed field to true, and commits the transaction with commitTransaction().