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From: Andrus Adamchik <andrus@objectstyle.org>
To: user@cayenne.apache.org
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Subject: Re: Sometimes no data from Relation to small tables
Date: Fri, 29 May 2009 10:12:59 +0300
References: <e0b37ed50905280716o5f7b0274qa8ef7a37bade1650@mail.gmail.com>

Strange. How is the relationship mapped? Is this a PK to dependent PK?

Andrus


On May 28, 2009, at 5:16 PM, Juergen Saar wrote:

> Hi,
>
> there is strange behavior on 1:1 Relations where the target-table  
> has only a
> small amount of data.
> In this cases I can see in the logfile, that there is no select for  
> data at
> all.
>
> I found a workaround ... I do an explizit select ... this works
> but the relation always brings hollow object
> perhaps it brings a little more understandin of the problem:
>
> One more thing: I turn caching off, because there is
> more Software on the System that works with this data.
>
> The Code Sniplet:
>
> I overwrite the readProperty from CayenneDataObject
> in my derived Class named MwareBusinessObject
> the 'expressionForRelation' is a helper working on base og the
> Cayenne-Configuration
>
>   public Object readProperty(String propName) {
>       Object result = null;
>       try {
>           result = super.readProperty(propName);
>          ...
>           if (result != null) {
>            ...
>               } else if (result instanceof MwareBusinessObject) {
>                   /*
>                    * @WORKAROUND
>                    */
>                   MwareBusinessObject bobj = (MwareBusinessObject)  
> result;
>                   if (bobj.getPersistenceState() ==
> PersistenceState.HOLLOW) {
>                       Expression ex =
> CayenneUtils.expressionForRelation(this, propName);
>                       SelectQuery query = new
> SelectQuery(result.getClass(), ex);
>                       List tmp = getDataContext().performQuery(query);
>                       if (tmp.size() == 1) {
>                           result = tmp.get(0);
>                       }
>                   }
>               }
>           }
>       } catch (Exception e) {
>     ...
>
>
> My Cayenne-Version is 2.0.4
>
> Sorry for not having tested the Problem with Version 3
> -Juergen-