NonUniqueException and ternary association

kantorn · **Posted:** Tue Feb 03, 2004 5:48 am

Hi!

Class InfoContact has the following mapping.

<hibernate-mapping>
<class
name="ks.rah.cainfo.db.model.InfoContact"
table="CONTACT"
dynamic-update="false"
dynamic-insert="false"
>
.
.
.
<list
name="data"
table="DATA"
lazy="false"
inverse="false"
cascade="save-update"
>

<key
column="CONTACT_FK"
/>

<index
column="INDEX_"
/>

<composite-element
class="ks.rah.cainfo.db.model.FieldValue"
>

<many-to-one
name="field"
class="ks.rah.cainfo.db.model.ContactField"
cascade="save-update"
outer-join="auto"
update="true"
insert="true"
column="FIELD_FK"
/>

<many-to-one
name="value"
class="ks.rah.cainfo.db.model.ContactMeta"
cascade="save-update"
outer-join="auto"
update="true"
insert="true"
column="VALUE_FK"
/>

</composite-element>

</list>
.
.
</class>

I would want the InfoContact-object to have a List of
FieldValue-object where the 'field' part isn't necessarily unique,
for example:

InfoContact:data
[field1; value1]
[field1; value2]
[field2; value7]
etc.

Problem in short is this:

When I execute the following code (JUnit-test)

public void testCreateNew() throws HibernateException
{
InfoContactDAO infomgr = new InfoContactDAO();
ContactMetaDAO metamgr = new ContactMetaDAO();
ContactFieldDAO fieldmgr = new ContactFieldDAO();
InfoContact contact = new InfoContact();
ContactField gender = fieldmgr.retrieve("K

kantorn · **Posted:** Tue Feb 03, 2004 5:58 am

And I've read

http://www.hibernate.org/117.html#A20

and still don't understand why InfoContact chokes on the ContactMeta-object that I loaded in another session....
I want to associate this ContactMeta object to the FieldValue object that in it's turn should be in a M:1-relation with the InfoContact.
(Why is it so hard to express one

kantorn · **Posted:** Tue Feb 03, 2004 7:17 am

Another thought...

I'm using the Thread Local-pattern for obtaining a Session object. Could this be the problem??

/F

emmanuel · **Posted:** Tue Feb 03, 2004 12:12 pm

can you simplify your code and show that do you smthgmgr ?

kantorn · **Posted:** Tue Feb 03, 2004 3:03 pm

emmanuel wrote:

can you simplify your code and show that do you smthgmgr ?

Reposted in a hopefully more readable format.

What does 'smthgmgr' mean? I'm from Sweeeden..... ;-)

/F

kantorn · **Posted:** Wed Feb 04, 2004 5:49 am

Well...

changed

Code:

cascade="save-update"

to

Code:

cascade="none"

in the InfoContact mapping. No NonUniqueObjectException anymore.

I'm still concerned about how to handle and think concerning DAO-classes and atomical database calls. Is this the right approach in conjunction with the Thread Local Session pattern? This is rather important to me since I'm developing in Tomcat/J2EE.

/F

emmanuel · **Posted:** Wed Feb 04, 2004 8:56 am

smthmgr => something manager in your code (*mgr):
[list=]infomgr
metamgr
fieldmgr [/list]

kantorn · **Posted:** Thu Feb 05, 2004 5:35 am

Hello Emmanuel and thanks for answering.

My manager classes handles database calls, I guess you could calll them DAO-classes. All methods follow the pattern of the method below.

Code:

public class ContactMetaDAO {
..
   public ContactMeta retrieve(String metadisplay) throws HibernateException
   {
      ContactMeta meta = null;
      List result = null;
      Session session = null;
      Transaction tx = null;
      
      try
      {
         session = HibernateSession.currentSession();
         tx = session.beginTransaction(); 
         result = session.find("from ContactMeta as meta where meta.displayValue = ?",
         metadisplay, 
         Hibernate.STRING );
         if(result == null || result.size() != 1 )
         {            
            return meta;
         }
         else
         {
            meta = (ContactMeta) result.get(0);
            //System.out.println(meta);   
         }
         tx.commit();
      }
      catch(HibernateException he)
      {
         if(tx!=null) tx.rollback();
         throw he;
      }
      finally
      {         
         HibernateSession.closeSession();   
      }
      return meta;
   }
..
}

InfoContactDAO:

Code:

public class InfoContactDAO {
   

   public Long create(InfoContact contact) throws HibernateException
   {
      Session session =    null;
      Transaction tx =    null;
      Long id = null;
      
      try
      {
         session = HibernateSession.currentSession();
         tx = session.beginTransaction();
                  session.saveOrUpdate(contact);         
         tx.commit();
      }
      catch(HibernateException he)
      {
         if(tx!=null) tx.rollback();
         throw he;
      }
      finally
      {         
         HibernateSession.closeSession();   
      }
      return id;
   }
}

I'm not sure if this is what you wanted to see...

Sincerely,

/F

emmanuel · **Posted:** Thu Feb 05, 2004 8:56 am

Using the Thread session pattern, I recommend you to manage Tx at a higher level (process level).
Have a look a Spring framework (at least for the concepts), it's based on pretty good patterns.

kantorn · **Posted:** Fri Feb 06, 2004 4:17 am

emmanuel wrote:

Using the Thread session pattern, I recommend you to manage Tx at a higher level (process level).
Have a look a Spring framework (at least for the concepts), it's based on pretty good patterns.

Hi, thanks for answering.

OK, let me see if I get you right.
My app is a servletbased one in TOMCAT. The overall idea is this:

UI (JSP, HTML)
communicates with
HttpHandler (invoked through a homemade front end servlet)
uses (through instantiation)
DAO-class
uses
Hibernate
communicates with
DB

Your suggestion is to move the operation (database calls) from the "DAO-class"-layer to "HttpHandler"-layer. Do I get it right?

This raises questions. For example, if I would want to keep the business layer-model(DAO-classes) , how do I best do that? Move the instatiation of the Session (or the Transaction even or both) to the HttpHandler layer, and send the Session (and/or Transaction) created to the DAO-methods as (an) argument(s)?

I feel a lot of portability/extendability is lost if I do a lot of melt-together of the HttpHandler and DAO-class layers. This is a fundamental design issue concerning servlets and Hibernate to which I haven't found a good answer yet.

Sincerely,

/F