In case of using Dao in validate process, the hibernate plugin doesn't inject Session (and i think Transaction.

Here is a Sample to reproduce the problem:

UserDaoImpl:

public class UserDaoImpl implements UserDao {

@SessionTarget
Session session;

@TransactionTarget
Transaction transaction;


@Override
public User getUser(Long id) {
        if (session==null) {
            System.out.println("Session is null");
        }
    // TODO Auto-generated method stub
           User user = null;
    try {

        Criteria criteria = session.createCriteria(User.class).add(
                Restrictions.eq("id", id_id));
        user = (User) criteria.uniqueResult();

    } catch (Exception e) {
        transaction.rollback();
        e.printStackTrace();
    }

    return user;
}

UserAction:

public class UserAction extends ActionSupport {

private UserDAO userDao = new UserDaoImpl();
private User user;

public String execute() { return "success"; }

public void validate() { clearFieldErrors(); user = userDao.getUser(1); ....

}

....

The Dao prints out "Session is null". NOTE: this is only sample code!

Have you tried putting your Dao request into the execute()-method? That's pretty much where I keep the database interaction.

Probably your validate()-method gets invoked before the session is injected. This might be the reason, why your session is null (and not "closed").

In the execute method it works, in validation the session remains null, in all cases.