Script: Class dw.system.Transaction

Class Transaction

Represents the current transaction. A transaction provides a context for performing atomic changes to persistent business objects. Before a business object can be created, changed, or deleted, a transaction must be started using the begin() method. All changes on the touched business objects will only be made durable when the transaction is committed with commit(). If a transaction is rolled back, all changes so far will be reverted and the business object will have their previous state again. It is possible to begin a transaction multiple times in a nested way (like begin-begin-commit-commit). In this case, in order to commit the changes the commit method must be called symmetrically as often as begin. It is also possible to run multiple transactions within a single request, one after another (like begin-commit-begin-commit). In case of any exception while working with business objects inside of a transaction, the transaction cannot be committed anymore, but only be rolled back. Business code may try to take appropriate actions if it expects business-related problems at commit (for example, constraint violations). When a transaction is still open at the end of a pipeline call, controller call, or job step, the remaining changes are committed unless an exception is thrown.

The following best practices exist for using transactions:

  • Avoid long running transactions in jobs.
  • Use one transaction for changes that belong together and need a joint rollback. In most cases, one transaction for all changes in a request is better than multiple transactions for each individual object.
  • Don’t begin and commit a huge number of small transactions in a loop.
  • Avoid changing the same objects in parallel transactions.

Example 1 - explicit control:

var txn = require('dw/system/Transaction'); txn.begin(); // work with business objects here txn.commit();

Example 2 - implicit control:

var txn = require('dw/system/Transaction'); txn.wrap(function(){ // work with business objects here });

Constructor Summary

This class does not have a constructor, so you cannot create it directly.

Method Summary

static begin() : void

Begins a transaction.

static commit() : void

Commits the current transaction.

static rollback() : void

Rolls back the current transaction.

static wrap(callback : Function) : Object

Encloses the provided callback function in a begin-commit transactional context.

Methods inherited from class Object

assign, create, create, defineProperties, defineProperty, entries, freeze, fromEntries, getOwnPropertyDescriptor, getOwnPropertyNames, getOwnPropertySymbols, getPrototypeOf, hasOwnProperty, is, isExtensible, isFrozen, isPrototypeOf, isSealed, keys, preventExtensions, propertyIsEnumerable, seal, setPrototypeOf, toLocaleString, toString, valueOf, values

Method Detail

begin

static begin() : void

Begins a transaction.

commit

static commit() : void

Commits the current transaction. The transaction must have been started with begin() before.

rollback

static rollback() : void

Rolls back the current transaction. The transaction must have been started with begin() before.

wrap

static wrap(callback : Function) : Object

Encloses the provided callback function in a begin-commit transactional context. If the transaction cannot be committed successfully, it is rolled back instead and an exception is thrown.

Parameters:

callback - a function that should be executed within a transactional context

Returns:

the result of the callback function, if it returns something