any other approach? Best practice?

elLord · **Joined:** Sat Jan 01, 2005 12:18 pm **Posts:** 23

I'm developing an application which is moving data from one source (e.g. database) to another with some transformations made inbetween. So it is a kind of a data integration tool at the current point.

I want to show my problem with a simple example. Somehow I have the feeling that I do it the wrong way.
- I have List with objects from one source
- I go through these objects, make changes in data, convert them into different data types and then I save the data in a new object which is associated with the new database

Code:

 public void makeItSo() {
        GenericServiceDAOExport genExport = new GenericServiceDAOExport(); // Database 1
        GenericServiceDAOImport genImport = new GenericServiceDAOImport(); // Database 2
  
        List list  = genExport.getAllObjects(new Bananna());   // getAllObjects from Database 1
        if (list.size() > 0) {  
           for (Iterator iter = list.iterator(); iter.hasNext(); ) {  
               Bananna bananna = (Bananna) iter.next();
               
               // create new Apple model and set some attributes from the previouse source... 
               Apple appleImp = new Apple();
               appleImp.setAppleId(bananna.getBanannaId());
               appleImp.setName(bananna.getBanannaName())

               // check if this recordset already exists - I have assigned IDs!
               if (genImport.getObjectById(appleImp,appleImp.getAppleId()) == null) {
                   genImport.save(appleImp); 
               } else {
                   genImport.update(appleImp);
               }
               appleImp = null;  
           } 
        } 

The Problem is that everytime the for loop starts I have to commit the transaction and close the session otherwise I get the error message:

Code:

a different object with the same identifier value was already associated with the session

Right now I do it in the save Method of GenericServiceDAOImport:

Code:

public void save(Object obj) {
        Session session = HibernateUtilImport.getSession(); 
        
        try { 
           HibernateUtilImport.beginTransaction();
            
           session.save(obj);
           
           HibernateUtilImport.commitTransaction();
            HibernateUtilImport.closeSession();
        } catch (HibernateException ex) { 
            throw new InfrastructureException(ex); 
        } 
}

Question: I don't think this is the right way to do it! Is there any other way to create a set of objects (like above) and then commit the transaction when I finished with all objects? Besides my approach is awfully slow ....

max · **Posted:** Fri Apr 01, 2005 9:32 am

you are putting the same entity in the session twice - dont do that ;)

elLord · **Joined:** Sat Jan 01, 2005 12:18 pm **Posts:** 23

Where do I put the same entity in the session twice?? The session is closed after every writing!

Why does this code work with Hibernate 3 and with 2.1 not ???

None of you ever made something like this?? Come on .. give me a hint how to do it better!