Delete doesn't work... Why? :(

javaman · **Posted:** Tue Nov 18, 2003 6:23 pm

Hi all,

Today I have tried to use hibernate to update my persistence mechanism. Everything was going ok, implemented some basic methods to save/update and load objects in my PersistenceBroker and so on... However, when I tried to implement a method to remove an instance of a PERSISTENT object, nothing happened. I tried to use the code bellow with and without the transaction scope, but nothing still haven't happened... WHAT'S GOING ON WITH MY CODE? :'( Suppose that user is an object instance that is correctly mapped as well as it has been loaded and saved correctly...

Code:

   Transaction tx = null;
   Session session = null;
   
   try {
      Session ss = PersistenceMechanism.getInstance().getSession();
      tx = session.beginTransaction();
   
      ss.delete(user); //<<<------ It doesn't work...??? Why?

      tx.commit();
   
   } catch (HibernateException he) {
      if (tx != null) 
         tx.rollback();
      throw he;
   
   } finally {
      session.close();
      
   }

nerotnt · **Joined:** Wed Oct 08, 2003 10:31 am **Posts:** 247

javaman wrote:

Hi all,

Today I have tried to use hibernate to update my persistence mechanism. ..

My delete's work fine. Are you instanciating a SessionFactory correctly? Where are you loading the class instance to delete? Looks to me you are not loading the instance in the right place. Try loading it before the delete.

Brannor McThife · **Posted:** Wed Nov 19, 2003 12:40 am

I think, that perhaps you need a ss.flush() after your delete? Not sure on that, as I don't delete records.

Reason for that is, you have no real way of checking the history of records then. On many of the projects I've work on, it has been specified that there be an "Active" field in each DB table, which is set to, e.g. 1, if the record is "deleted". That way, you still have your records, just you can specify in your queries to: Active <> 1.

Oh, and you're using 2 different sessions?

Session session, and Session ss, so when you call tx.commit, it's not actually committing your ss.delete()

-G

gavin · **Posted:** Wed Nov 19, 2003 12:41 am

No he doesn't need to flush.

Perhaps you need to check your unsaved-value mapping. Maybe Hibernate thinks the object is transient.

javaman · **Posted:** Wed Nov 19, 2003 7:37 pm

Hi All,

Thank you for your attention and replies... First of all the code I put here was indeed wrong... It contains 2 sessions... :)

The code that worked was the one with flush() after the delete...

Code:

Session ss = PersistenceMechanism.getInstance().getSession();
ss.delete(user);
ss.flush();

My SessionFactory is created inside my singleton PersistenceMechanism, and it's through that instance is that I use getSession() to get the session instance...

The mapping of the class has the following unsaved-value in its id tag:

Code:

As Gavin told that it wasn't necessary to flush after delete, I realize that it could be the mapping about the unsaved-value... So, if anyone has a suggestion, please let me know...

regards,

Brannor McThife · **Posted:** Thu Nov 20, 2003 1:43 am

Can you post the full mapping for that object? Your code, as we've seen, looks fine, so the problem may be in the mapping.

-G

emmanuel · **Posted:** Thu Nov 20, 2003 3:22 am

Stupid tip but... The user you delete has id=null ?

javaman · **Posted:** Thu Nov 20, 2003 12:05 pm

Hi guys,

Brannor, the following is the user mapping... and epbernard, sure it wasn't with an id null... :)

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
   "-//Hibernate/Hibernate Mapping DTD//EN"
   "http://hibernate.sourceforge.net/hibernate-mapping.dtd">

<hibernate-mapping>
   <class name="br.ufal.cryptonline.User" table="user">

      <id name="id" type="string" unsaved-value="null">
            <column name="OID" sql-type="char(32)" not-null="true"/>
            <generator class="uuid.hex"/>
      </id>
      <property name="firstName">
         <column name="firstName" sql-type="varchar(20)" not-null="true"/>         
      </property>
      
      <property name="lastName">
         <column name="lastName" sql-type="varchar(20)" not-null="true"/>               
      </property>
      
      <property name="email">
         <column name="email" sql-type="varchar(100)" not-null="true"/>               
      </property>
      
      <property name="password">
         <column name="password" sql-type="varchar(15)" not-null="true"/>               
      </property>
      
      <property name="publicKeyN">
         <column name="publicKeyN" sql-type="varchar(20)" not-null="true"/>               
      </property>
      
      <property name="publicKeyE">
         <column name="publicKeyE" sql-type="varchar(20)" not-null="true"/>               
      </property>
      
      <property name="privateKeyD">
         <column name="privateKeyD" sql-type="varchar(20)" not-null="true"/>               
      </property>
   </class>
</hibernate-mapping>

The problem is that I have to flush after delete an object...

thank u for your attention...

Brannor McThife · **Posted:** Fri Nov 21, 2003 12:57 am

I went reading through the reference doc, and came across this:

Quote:

Session.delete() will remove an object's state from the database. Of course, your application might still hold
a reference to it. So it's best to think of delete() as making a persistent instance transient.

Now, I know that this probably isn't the issue, but it's something worth considerring.

Your mapping looks fine though, from what we can see. All I can think of would be maybe to try evict the user from the session after your delete. Dunno really. :/

-G

gavin · **Posted:** Fri Nov 21, 2003 1:06 am

Show a debug-level Hibernate log.

javaman · **Posted:** Fri Nov 21, 2003 2:20 am

Brannor,

I have also read this part of the doc and it seems to me just fine... The only thing is that on some examples it's not necessary to use it... I have just finished to implement a persistence mechanism adapter for Hibernate... I was involved in a project that used OJB about six months ago and now I'm responsible for update the persistence layer with Hibernator... So, I'm still just using Junit to test the implementation... The UML diagram is as bellow...

[img]http://www.mycgiserver.com/~marcellojunior/projects/cryptonline/doc/images/PersistenceLayerFactory.gif
[/img]

So, I'll be using it to and try to get it running with no problems... I'll be still using the flush method... :)

Thank you for your attention...