Tuesday, January 12, 2010

The Curious Case of Damned DataIntegrityViolationException

In one of the projects on which I contract, we recently started encountering a problem importing and parsing text record files into our system which previously had no problem. My first thought on hearing this was that the partner from which we obtain the files had changed the file format (again). Upon closer inspection, nothing had changed in the files. My next step was to try importing them into a development system and seeing what was going on. As it turned out, the application was catching Spring's DataIntegrityViolationException. I was floored as soon as I saw this because our application was supposed to be catching this exception behind one of the business interfaces and converting it to an internal exception which is used in business logic. After some more poking around to confirm what was really going on, I threw the problem into google, and on the second result was a post in the Spring forum made by a user having exactly the same problem I was.

To summarize their problem quickly, they were using a transaction manager, and they were intercepting their business methods (via interfaces) with Aspects, which we're also doing. The problem was this : as soon as the internal Aspects were applied to the business interface, this changed the ordering of advice applied to the interface implementor, so now the Hibernate session underneath was getting flushed later by the transaction manager, instead of in the business method where it had been flushed previously. The result of this was that now DataIntegrityViolationExceptions were being thrown outside of the interecepted method, instead of inside where it was expected. A manual session.flush() inside of a HibernateCallback within the business method fixed this :

* @see AchPaymentNoticeOfChangeService#registerNoc(AchPaymentNoticeOfChange)
public void registerNoc(final AchPaymentNoticeOfChange changeNotification) throws IllegalArgumentException, NoticeOfChangeAlreadyExistsException, Exception {
try {
getHibernateTemplate().execute(new HibernateCallback() {
public Object doInHibernate(Session session) throws HibernateException, SQLException {

session.save (changeNotification);

// flush the session to ensure that the database gets synchronized
// the end of this call, rather than waiting for any transaction
// managers to handle it and risk letting a DataIntegrityViolationException
// occur outside of this method's handling

return null;
} catch (DataIntegrityViolationException dive) {
throw new NoticeOfChangeAlreadyExistsException("A notice of change already exists for payment ["+changeNotification.getAchPayment().getId()+"]", dive, changeNotification);
} catch (Exception e) {
throw e;

I hope this post finds somebody else who runs into this problem.

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