recover Hibernate session state after a failed insert

Question

The following code tries to insert an Item object to the db, using Spring+Hibernate. The Item has an Integer id field as primary key, as well as a name column which is subject to a unique constraint (simplified example).
I know that the item's id is null (the item is transient) however the insert may still fail due to the unique constraint on the name field.

try {
  getHibernateTemplate().save(myItem);
  getHibernateTemplate().flush(); // exception thrown here if the name is not unique
}
catch (DataIntegrityViolationException e) {
  Item itemFromDb = (Item) getHibernateTemplate()
    .find("from Item item where item.name = ?",
           myItem.getName()).get(0);
  //
  // copy some properties from myItem to itemFromDb
  //
  getHibernateTemplate.update (itemFromDb)
}

I need this code to run in a loop for many items, all in one transaction, that's why I am trying to issue an update if the insert fails.

However, after the insert fails, the hibernate session is in a strange state, and when I issue the select statement to obtain the item from the db, the original exception is thrown.

I tried using session.evict() after the insert fails, but to no avail. Any idea?

This is what I see in the console after the select fails. Hibernate fails on the select statement but still prints information about the previous insert statement.

WARN  [http-8080-1] hibernate.util.JDBCExceptionReporter (JDBCExceptionReporter.java:77) - SQL Error: 2627, SQLState: 23000
ERROR [http-8080-1] hibernate.util.JDBCExceptionReporter (JDBCExceptionReporter.java:78) - Violation of UNIQUE KEY constraint 'unq_Item_name'. Cannot insert duplicate key in object 'items'.
ERROR [http-8080-1] event.def.AbstractFlushingEventListener (AbstractFlushingEventListener.java:301) - Could not synchronize database state with session
org.hibernate.exception.ConstraintViolationException: could not insert: [com.sample.Item]
    at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:71)

P.S. please don't tell me about hibernate's saveOrUpdate method, I know what it does.

Answer 1

Hibernate does not guarantee anything about a session once a database exception is thrown. You are supposed to roll-back. If I understand Bozho's suggestion, he's saying that you should read from the name column first to ensure that the insert won't fail. Makes sense to me.