Rollback transaction in hibernate

[Andris Sigs]

Hello.
I've created Hibernate „create” method:

public PK create(T o) {
    try {

        getSession().beginTransaction();
        PK rez = (PK) getSession().save(o);
        getSession().flush();
        getSession().getTransaction().commit();
        return rez;
    }
    catch (Exception e){
        e.printStackTrace();
        getSession().getTransaction().rollback();
        return null;
    }

}

When some exception occurs (for example, unique constraint in DB), then catch block executes. After one error, I cant create another rows… I get exception about old error. For example, I create user „test”, then I trying add user with same name „test” and I’m getting hibernate error in log file. Then I’m trying to add new unique user, with new username „test2”, but still get old error about „test” user. Where is the problem?

So, real example:

I'm added [e-mail], after that, I tryed add this user once more (and gets exception(below))... Now I'm trying to add user "[e-mail]" but I'm getting this error about [e-mail] again:

[2014-03-23T17:35:17.767+0200] [glassfish 4.0] [WARN] [] [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] [tid: _ThreadID=22 _ThreadName=http-listener-1(5)] [timeMillis: 1395588917767] [levelValue: 900] [[
  SQL Error: 0, SQLState: 23505]]

[2014-03-23T17:35:17.767+0200] [glassfish 4.0] [ERROR] [] [org.hibernate.engine.jdbc.spi.SqlExceptionHelper] [tid: _ThreadID=22 _ThreadName=http-listener-1(5)] [timeMillis: 1395588917767] [levelValue: 1000] [[
  ERROR: duplicate key value violates unique constraint "unique_Username"
  Detail: Key (username)=([e-mail] ) already exists.]]

[2014-03-23T17:35:17.767+0200] [glassfish 4.0] [SEVERE] [] [] [tid: _ThreadID=22 _ThreadName=Thread-4] [timeMillis: 1395588917767] [levelValue: 1000] [[
  org.hibernate.exception.ConstraintViolationException: could not execute statement
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:129)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:136)
    at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:58)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3067)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3509)
    at org.hibernate.action.internal.EntityInsertAction.execute(EntityInsertAction.java:88)
    at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:377)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:369)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:286)
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:339)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52)
    at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1234)
    at org.test.majas.dao.GenericDaoImpl.create(GenericDaoImpl.java:29)
    at org.test.majas.beans.TestBean.addUser(TestBean.java:80)
    .....
Caused by: org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "unique_Username"
  Detail: Key (username)=([e-mail] ) already exists.
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2161)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1890)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:560)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:417)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:363)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:133)
    ... 63 more]]

Thanks.

[Andris Sigs]

Any ideas? Please help.

[Martin Vajsar]

Are you sure you're interpreting the logs correctly? I don't see two identical error messages with different timestamp in your log.

If you're getting this result consistently, perhaps you could create a SSCCE?

By the way, catching Exception and returning null instead doesn't look good to me. I'd prefer to have an exception unwind through the application to the level where it can be handled (probably to the point where you're able to tell the user an error has happened). But I don't think this is the cause of your problems.

[Andris Sigs]

So, problem was in Session… After each error I must create new Session…

[Martin Vajsar]

Yes, that's true. Thanks for sharing the solution!