When transactions are necessary vs unnecessary in MongoDB - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a transaction in MongoDB.

MongoDB

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

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

AstartTransaction

BcommitTransaction

CabortTransaction

DendSession

Attempts:

3 left

💡 Hint

Common Mistakes

Using commitTransaction instead of startTransaction

Calling endSession before starting a transaction

To begin a transaction in MongoDB, you use startTransaction() on the session.

2fill in blank

medium

Complete the code to commit a transaction after operations.

MongoDB

await session.[1]();

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

AstartTransaction

BabortTransaction

CcommitTransaction

DendSession

Attempts:

3 left

💡 Hint

Common Mistakes

Calling startTransaction again instead of commitTransaction

Using abortTransaction when you want to save changes

After completing operations in a transaction, you commit it with commitTransaction().

3fill in blank

hard

Fix the error in the code to abort a transaction properly.

MongoDB

try {
  await session.commitTransaction();
} catch (error) {
  await session.[1]();
}

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

AstartTransaction

BabortTransaction

CcommitTransaction

DendSession

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to start a new transaction inside the catch block

Calling commitTransaction again instead of abortTransaction

If committing a transaction fails, you should abort it using abortTransaction() to undo changes.

4fill in blank

hard

Fill both blanks to create a transaction that updates two collections atomically.

MongoDB

const session = client.startSession();
try {
  session.[1]();
  await collection1.updateOne(filter1, update1, { session });
  await collection2.updateOne(filter2, update2, { session });
  await session.[2]();
} finally {
  await session.endSession();
}

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

AstartTransaction

BcommitTransaction

CabortTransaction

DendSession

Attempts:

3 left

💡 Hint

Common Mistakes

Using abortTransaction instead of commitTransaction

Not starting the transaction before updates

Start the transaction with startTransaction() and commit it with commitTransaction() after updates.

5fill in blank

hard

Fill all three blanks to handle a transaction with error rollback and session cleanup.

MongoDB

const session = client.startSession();
try {
  session.[1]();
  await collection.updateOne(filter, update, { session });
  await session.[2]();
} catch (error) {
  await session.[3]();
} finally {
  await session.endSession();
}

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

AstartTransaction

BcommitTransaction

CabortTransaction

DendSession

Attempts:

3 left

💡 Hint

Common Mistakes

Not aborting the transaction on error

Not starting the transaction before operations

Start the transaction, commit if successful, and abort if there is an error.