gajus/slonik slonik@48.2.0 on GitHub

Transaction events

Transaction connections provide event emitter functionality to monitor transaction lifecycle events. This allows you to listen for transaction commits, rollbacks, and savepoint operations.

await connection.transaction(async (transactionConnection) => {
  // Listen for commit events
  transactionConnection.on('commit', ({transactionId, transactionDepth}) => {
    console.log(`Transaction ${transactionId} committed at depth ${transactionDepth}`);
  });

  // Listen for rollback events
  transactionConnection.on('rollback', ({transactionId, transactionDepth, error}) => {
    console.log(`Transaction ${transactionId} rolled back:`, error.message);
  });

  // Access transaction metadata
  console.log('Transaction ID:', transactionConnection.transactionId);
  console.log('Transaction Depth:', transactionConnection.transactionDepth);

  await transactionConnection.query(sql.unsafe`INSERT INTO foo (bar) VALUES ('baz')`);
  
  // Commit event will be emitted automatically when transaction completes
});

Available Events:

commit - Emitted when a top-level transaction (depth = 0) commits successfully
- Parameters: (event: {transactionId: string, transactionDepth: number})
rollback - Emitted when any transaction rolls back due to an error
- Parameters: (event: {transactionId: string, transactionDepth: number, error: Error})
savepoint - Emitted when a nested transaction creates a savepoint (depth > 0)
- Parameters: (event: {transactionId: string, transactionDepth: number})
rollbackToSavepoint - Emitted when a nested transaction rolls back to its savepoint
- Parameters: (event: {transactionId: string, transactionDepth: number, error: Error})

Nested Transaction Events:

await connection.transaction(async (outerTransaction) => {
  outerTransaction.on('savepoint', ({transactionId, transactionDepth}) => {
    console.log(`Savepoint created at depth ${transactionDepth}`);
  });

  outerTransaction.on('commit', ({transactionId, transactionDepth}) => {
    console.log(`Transaction committed at depth ${transactionDepth}`);
  });

  await outerTransaction.transaction(async (innerTransaction) => {
    // This will emit a 'savepoint' event
    // innerTransaction shares the same event emitter as outerTransaction
    await innerTransaction.query(sql.unsafe`INSERT INTO nested (value) VALUES ('test')`);
  });

  // Only the outer transaction will emit a 'commit' event
});

Transaction Metadata:

Transaction connections provide access to transaction metadata:

transactionId - Unique identifier for the transaction (consistent across nested levels)
transactionDepth - Current nesting level (0 for top-level, 1+ for nested transactions)

All standard EventEmitter methods are available: on(), off(), once(), removeListener(), removeAllListeners(), etc.