system.db.rollbackTransaction

This function is used in Python Scripting.

Description

Performs a rollback on the given connection. This will make all statements executed against this transaction since its beginning or since the last commit or rollback undone.

If you are done with the transaction, you must also close it after you do a rollback on it.

Client Permission Restrictions

This scripting function has no Client Permission restrictions.

Syntax

system.db.rollbackTransaction(tx)

Parameters

Type	Parameter	Description
String	tx	The transaction ID.

Returns

Nothing

Scope

Gateway, Vision Client, Perspective Session

Code Examples

Python - Rollback a Transaction on an Exception

# This example uses a for-loop to run multiple queries in a single Transaction, and rollback if an error occurs.
 
# Create some variables for use later.
txId = system.db.beginTransaction(timeout=5000)
status=2
query = "UPDATE MachineStatus SET status=? WHERE ID=?"
errors = False  # A flag to denote if we ran into a problem with a query during the transaction.
 
for machineId in range(8): 
    try:       
        system.db.runPrepUpdate(query,  args=[status, machineId], tx=txId)     
    except:
        errors = True  
        break
# If we encountered an error...
if errors:
    # ...then rollback the transaction
    system.db.rollbackTransaction(txId)
else:
    # Otherwise, commit it.
    system.db.commitTransaction(txId)
# In either case, close the transaction when we're done.
system.db.closeTransaction(txId)