RE: [OJB-developers] n:m-Mapping with Extent

[Amit G. <ago...@de...>]

Is there a patch available for this bug?  This is wreaking major havoc
on our project.

Amit

-----Original Message-----
From: Jakob Braeuchi [mailto:jbr...@ho...]
Sent: Tuesday, April 30, 2002 11:55 AM
To: obj...@li...;
Joa...@tp...
Subject: Re: [OJB-developers] n:m-Mapping with Extent


hi joachim,

a clean approach would be to have  a method in QueryFactory with a query
and
a class as parameters.
the factory should then return a clone (how deep ?) of the query with
all
criteria and tables etc. based on the new class.

greetings jakob


----- Original Message -----
From: <Joa...@tp...>
To: <obj...@li...>
Sent: Tuesday, April 30, 2002 9:48 AM
Subject: Re: [OJB-developers] n:m-Mapping with Extent


>
> Hy,
>
> I've already done what you suggested (rebuild a new query), but it was
a
> very ugly hack, as I didn't know where to put it and how to do it
properly
> ( I don't even want to mention were I did it ;-). It broke some other
tests
> 'though and I decided to do a clean approach, rather then debug this
ugly
> piece of code that I produced. At least I saw that extents in
combination
> with MtoN-mappings are possible. Is it possible to provide
> QueryByMtoNCriteria with the necessary information to rebuild itself
for a
> specific extent-class/table? I think that would be somewhat nicer.
>
> regards
> Joachim Sauer
>
>
>
>
>                     "Jakob
>                     Braeuchi"            An:
<obj...@li...>,
<Joa...@tp...>
>                     <jbraeuchi@ho        Kopie:
>                     tmail.com>           Thema:  Re: [OJB-developers]
n:m-Mapping with Extent
>
>                     30.04.2002
>                     09:08
>
>
>
>
>
> hi joachim,
>
> as you mentioned the problem is the wrong table in from- and
where-clause
> coming from prebuilt MtoNQuery.
> the second problem is getPreparedSelectStatement() in SqlGenerator:
for
> MtoNQQueries tables are taken from the query and NOT from
> the ClassDescriptor, the query still pointing to the tables of the
base
> class instead of the extent. the same is true for the
EqualToColumnCriteria
> in the query.
>
> i think when using extents there is always a mismatch between the
query
and
> the class descriptor but it only hurts with MtoNQuery.
> it may be the best thing to build a new query based on the original
one
for
> the extents and then to execute this query.
> what do you think ?
>
> jakob
>
>
> ----- Original Message -----
> From: <Joa...@tp...>
> To: <obj...@li...>
> Sent: Monday, April 29, 2002 3:04 PM
> Subject: [OJB-developers] n:m-Mapping with Extent
>
>
> > Hy,
> >
> > it's me again. I've finally hunted down the bug. Let me explain the
> > scenario:
> >
> > I've got a class OneSide. Each object can have one or more ManySide
> > objects. This is implemented via a List with coresponding
> > CollectionDescriptor using a association-table (non-decomposed
> N:M-Mapping
> > in OJB-speak). Additionally there is a class named ManySideExtent,
that
> > extends ManySide and is mapped to another table.
> >
> > When I enable debugging in SqlGenerator I'll find the following
messages
> > (after many others)  when loading a OneSide object:
> >
> > [ojb.broker.accesslayer.SqlGenerator] DEBUG: SQL: SELECT
> > manyside.id,manyside.value FROM manyside, oneside_manyside WHERE
> > (oneside_id=3D ? )  AND oneside_manyside.manyside_id=3Dmanyside.id
> >
> > this one looks quite correct and gets me the correct results (all
> ManySide
> > objects that belong to the one OneSide object), but the next one
(which
> > tries to load the ManySideExtent objects) fails:
> >
> > [ojb.broker.accesslayer.SqlGenerator] DEBUG: SQL: SELECT
> >
manyside_extent.id,manyside_extent.value,manyside_extent.another_value
> FROM
> > manyside, oneside_manyside WHERE (oneside_id=3D ? )  AND
> > oneside_manyside.manyside_id=3Dmanyside.id
> >
> > the problem here obviously is, that the wrong table is used in the
> > FROM-clause and the WHERE-clause. These come from the Query object,
that
> is
> > created by the PersistenceBrokerImpl in getMtoNQuery. I think
calling
> > getMtoNQuery with the ClassDescriptor of ManySideExtent for the
second
> > query would solve the problem, the problem is, that the query is not
> built
> > in the function that decides wether we need to query for extents ...
> >
> > Maybe a correct solution would be somewhere else altogether, but I
don't
> > know enough about the system to see where.
> >
> > regards
> > Joachim Sauer
> >
> >
> > _______________________________________________
> > Objectbridge-developers mailing list
> > Obj...@li...
> > https://lists.sourceforge.net/lists/listinfo/objectbridge-developers
> >
>
>
>
>
>
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>

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