Re: Antwort: RE: How to map optional 1:1 relationship

Jakob Braeuchi Wed, 15 Oct 2003 08:49:44 -0700

hi gerhard,

sorry, i posted to wrong code. this is it:


    protected void associateBatched(Collection owners, Collection children)
    {
        ObjectReferenceDescriptor ord = getObjectReferenceDescriptor();
        ClassDescriptor cld = getOwnerClassDescriptor();
        Object owner, relatedObject;
        Object fkValues[];
        Identity id;
        PersistenceBroker pb = getBroker();
        PersistentField field = ord.getPersistentField();
        Class topLevelClass = pb.getTopLevelClass(ord.getItemClass());
        Iterator iter = owners.iterator();

        while (iter.hasNext())
        {
            owner = iter.next();
            fkValues = ord.getForeignKeyValues(owner,cld);
            if (!isNull(fkValues))
            {
                id = new Identity(null, topLevelClass, fkValues);
                relatedObject = pb.getObjectByIdentity(id);
            }
            else
            {
                relatedObject = null;
            }
            field.set(owner, relatedObject);
        }
    }

jakob

[EMAIL PROTECTED] wrote:

hi again,

I think this is indeed the reason. In my log files those selects almost always occur right after prefetch queries. And in the few cases they don't, it may just be that there was no non-null FK to prefetch.

Method ReferencePrefetcher#buildPrefetchQueries already checks for isNull(fkValues) so #associateBatched should probably do the same.

Gerhard
Jakob Braeuchi <[EMAIL PROTECTED]>
15.10.2003 17:17
Bitte antworten an "OJB Users List"
An: OJB Users List <[EMAIL PROTECTED]> Kopie: Thema: Re: Antwort: RE: How to map optional 1:1 relationship

hi carl,gerhard,
your right, fkValues may be null and thus a query will be fired.
can you confirm this gerhard ?
jakob

Boyes, Carl wrote:
Hi Jakob, Gerhard

In ReferencePrefetcher#associateBatched:
...
       while (iter.hasNext())
       {
           owner = iter.next();
           fkValues = ord.getForeignKeyValues(owner,cld);
           id = new Identity(null, topLevelClass, fkValues);
           relatedObject = pb.getObjectByIdentity(id);
           field.set(owner, relatedObject);
       }
...
Should this also be ensuring a non null foreign key value?

Carl.
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Wednesday, October 15, 2003 3:59 PM
To: OJB Users List
Subject: Re: Antwort: RE: How to map optional 1:1 relationship
Hi Jakob,

I just checked and you are right.

Nevertheless I find a lot of statements like SELECT ... FROM ... WHERE id='' in my P6Spy logs, where id is a not nullable primary key. I was assuming these were generated from resolving references with FK=null,
but
it turns out this is wrong. Looks like I'll have to do a little more research to find the reason for these selects...
Regards,
Gerhard
Jakob Braeuchi <[EMAIL PROTECTED]>
15.10.2003 16:10
Bitte antworten an "OJB Users List"
An: OJB Users List <[EMAIL PROTECTED]> Kopie: Thema: Re: Antwort: RE: How to map optional 1:1 relationship

hi gerhard,

imo this is already implemented. see PersistenceBrokerImpl#getReferencedObject:
...
        // BRJ: check if we have non null pk values
        // TBD  we should also check primitives
        // to avoid creation of unmaterializable proxies
        for (int i = 0; i < pkVals.length; i++)
        {
            if (pkVals[i] != null)
            {
                allPkNull = false;
                break;
            }
        }
        // BRJ: if all pk values are null there's no referenced object
        if (allPkNull)
        {
            return null;
        }
...
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Re: Antwort: RE: How to map optional 1:1 relationship

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