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From "Mike Kienenberger" <mkien...@gmail.com>
Subject Re: Self joins
Date Thu, 18 Jan 2007 20:52:02 GMT
This is pure speculation, but maybe it has something to do with path
splitting.   In that case, using the outer join patches I posted will
probably fix it.   You'd have to convert the patch from the 1.2
packages to the 2.0 packages, though.

Or if you created a simple 1.2 example demonstrating the problem, I
could check the output under 1.2 with the outer join patch installed.

I vaguely seem to recall hitting and fixing self-join issues when I
was working on the outer join patch.

On 1/18/07, Andrus Adamchik <andrus@objectstyle.org> wrote:
> Hmm... looks like a bug in the prefetch code. Could you possible open
> a bug report, somebody will take a look.
>
> http://issues.apache.org/cayenne
>
> Thanks
> Andrus
>
>
> On Jan 18, 2007, at 11:14 AM, Patric Lichtsteiner wrote:
>
> >
> > Hi
> >
> > I'm using Cayenne 2.0.1 and I'm working with a model with a self join
> > like this:
> >
> > <db-entity name="PathElement">
> >       <db-attribute name="ID" type="INTEGER" isPrimaryKey="true"
> > isMandatory="true"/>
> >       <db-attribute name="Name" type="VARCHAR" isMandatory="true"
> > length="100"/>
> >       <db-attribute name="ParentPathElementId" type="INTEGER"/>
> > </db-entity>
> >
> > <db-relationship name="parentPathElement" source="PathElement"
> > target="PathElement" toMany="false">
> >       <db-attribute-pair source="ParentPathElementId" target="ID"/>
> > </db-relationship>
> > <db-relationship name="subPathElements" source="PathElement"
> > target="PathElement" toMany="true">
> >       <db-attribute-pair source="ID" target="ParentPathElementId"/>
> > </db-relationship>
> >
> > <obj-entity name="PathElement"
> > className="com.encodo.test.cayenne.PathElement"
> > dbEntityName="PathElement">
> >       <obj-attribute name="name" type="java.lang.String"
> > db-attribute-path="Name"/>
> > </obj-entity>
> >
> > <obj-relationship name="parentPathElement" source="PathElement"
> > target="PathElement" db-relationship-path="parentPathElement"/>
> > <obj-relationship name="subPathElements" source="PathElement"
> > target="PathElement" db-relationship-path="subPathElements"/>
> >
> > The database scheme and the classes are correctly generated with this
> > definition. Inserting data with java code also works without problems,
> > but executing a query does not work as I would expect it (the database
> > contains a root PathElement and 2 sub PathElements):
> >     SelectQuery pathElementQuery = new SelectQuery(PathElement.class,
> > Expression.fromString("parentPathElement = null"));
> >     pathElementQuery.addPrefetch("subPathElements");
> >     List<PathElement> rootPathElements =
> > _context.performQuery(pathElementQuery);
> >     //Root element is found
> >     List<PathElement> subPathElements =
> > rootPathElements.get(0).getSubPathElements();
> >     //subPathElements.size() is 0, that's wrong!
> >
> > The following queries are executed by Cayenne:
> > SELECT t0.Name, t0.ParentPathElementId, t0.ID FROM PathElement t0
> > WHERE
> > t0.ParentPathElementId IS NULL
> > SELECT t0.Name, t0.ParentPathElementId, t0.ID FROM PathElement t0,
> > PathElement t1 WHERE t0.ParentPathElementId = t1.ID AND
> > (t0.ParentPathElementId IS NULL)
> >
> > IMHO, this query is wrong. The condition should be:
> > t1.ParentPathElementId IS NULL
> >
> > What is going wrong here? Has anybody an idea?
> >
> > Thanks a lot
> > Patric
> >
>
>

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