How to Abort a Transaction in MongoDB: Syntax and Examples

To abort a transaction in MongoDB, use the abortTransaction() method on the session object. This stops all operations in the current transaction and rolls back any changes made during it.

Syntax

The abortTransaction() method is called on a session object to cancel the current transaction. It must be called within an active transaction.

• session: The client session that started the transaction.
• abortTransaction(): Method that aborts the transaction and rolls back changes.

javascript

const session = client.startSession();
session.startTransaction();
// perform operations
await session.abortTransaction();
session.endSession();

Example

This example shows how to start a transaction, perform an operation, and then abort the transaction to undo the changes.

javascript

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

async function run() {
  const client = new MongoClient('mongodb://localhost:27017');
  await client.connect();
  const session = client.startSession();

  try {
    session.startTransaction();
    const collection = client.db('testdb').collection('testcol');

    await collection.insertOne({ name: 'Alice' }, { session });

    // Abort the transaction to undo the insert
    await session.abortTransaction();

    console.log('Transaction aborted, changes rolled back.');
  } finally {
    await session.endSession();
    await client.close();
  }
}

run().catch(console.dir);

Output

Transaction aborted, changes rolled back.

Common Pitfalls

• Calling abortTransaction() outside an active transaction causes errors.
• Not ending the session after aborting can lead to resource leaks.
• Forgetting to use the session object in operations inside the transaction means changes won't be part of the transaction.

javascript

/* Wrong way: aborting without starting a transaction */
const session = client.startSession();
try {
  await session.abortTransaction(); // Error: no active transaction
} finally {
  await session.endSession();
}

/* Right way: */
const session = client.startSession();
session.startTransaction();
// perform operations
await session.abortTransaction();
await session.endSession();

Quick Reference

Remember these key points when aborting transactions in MongoDB:

• Use abortTransaction() on the session object.
• Only call it during an active transaction.
• Always end the session after aborting.
• Operations inside the transaction must include the session.

Key Takeaways

Use session.abortTransaction() to cancel and roll back a MongoDB transaction.

Always start a transaction with session.startTransaction() before aborting.

Include the session in all operations inside the transaction.

End the session with session.endSession() to free resources.

Calling abortTransaction() outside a transaction causes errors.