NEWBIE: cannot update object with ODMG

[Farnea Massimiliano <ma...@atscom.it>]

I'm testing the ODMG layer with this example:

   /**
     *  Update the Traente instance on the database
     */

    public void update() {

        Database db = odmg.newDatabase(); // the current DB
        Transaction tx = null;
        //open database
        try {
            db.open("default", Database.OPEN_READ_WRITE);
        } catch (ODMGException ex) {
            ex.printStackTrace();
        }

        tx = odmg.newTransaction();
        String oqlQuery = "select edit from " +
                traente.className +
                " where id = " + traente.getId();
        try {
            tx = odmg.newTransaction();
            tx.begin();

            OQLQuery query = odmg.newOQLQuery();
            query.create(oqlQuery);
            DList result = (DList) query.execute();
            Traente toBeEdited = (Traente) result.get(0);

            tx.lock(toBeEdited, Transaction.UPGRADE);

            toBeEdited = traente;
            tx.commit();
        } catch (Throwable t) {
            // rollback in case of errors
            tx.abort();
            t.printStackTrace();
        }finally {
            try {
                db.close();
                System.out.println("DB closed!!!!");
            } catch (ODMGException ex) {
                ex.printStackTrace();
            }
        }
    }


where 'traente' is a class attribute that rapresents the updated object that
i would like to persist.

After the method invocation .... the database still contains the old object,
while retrieving again the reference 'toBeEdited' it seems to be updated.
What do I miss? I'm using a test class on JBuilder, without any particular
deployement enviroment.

Thanks in advance

Massimiliano Farnea

Re: NEWBIE: cannot update object with ODMG

[Guido Beutler <gu...@hrs.de>]

Hi,

----- Original Message -----
From: "Farnea Massimiliano" <ma...@atscom.it>
To: <oj...@db.apache.org>
Sent: Thursday, March 06, 2003 12:58 PM
Subject: NEWBIE: cannot update object with ODMG


> I'm testing the ODMG layer with this example:
>
>    /**
>      *  Update the Traente instance on the database
>      */
>
>     public void update() {
>
>         Database db = odmg.newDatabase(); // the current DB
>         Transaction tx = null;
>         //open database
>         try {
>             db.open("default", Database.OPEN_READ_WRITE);
>         } catch (ODMGException ex) {
>             ex.printStackTrace();
>         }
>
>         tx = odmg.newTransaction();

>         String oqlQuery = "select edit from " +
>                 traente.className +
>                 " where id = " + traente.getId();
>         try {
>             tx = odmg.newTransaction();

you got 2 transactions now. I think you need only one.

>             tx.begin();
>
>             OQLQuery query = odmg.newOQLQuery();
>             query.create(oqlQuery);
>             DList result = (DList) query.execute();
>             Traente toBeEdited = (Traente) result.get(0);
>
>             tx.lock(toBeEdited, Transaction.UPGRADE);

At the tutorial page the OJB crew uses

        tx.lock(toBeEdited, Transaction.WRITE);

for updating values.

>
>             toBeEdited = traente;

what's traente at that point?

>             tx.commit();

second transaction is commited but the first one is still in use.

cheers,

Guido

>         } catch (Throwable t) {
>             // rollback in case of errors
>             tx.abort();
>             t.printStackTrace();
>         }finally {
>             try {
>                 db.close();
>                 System.out.println("DB closed!!!!");
>             } catch (ODMGException ex) {
>                 ex.printStackTrace();
>             }
>         }
>     }
>
>
> where 'traente' is a class attribute that rapresents the updated object
that
> i would like to persist.
>
> After the method invocation .... the database still contains the old
object,
> while retrieving again the reference 'toBeEdited' it seems to be updated.
> What do I miss? I'm using a test class on JBuilder, without any particular
> deployement enviroment.
>
> Thanks in advance
>
> Massimiliano Farnea
>
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