Hi,
I'm not sur to understand, but ...
you have :
Class A
{
Integer idA;
String attribute1_A;
String attribute2_A;
...
Collection listOfA
}
if your repository is like this :
<class-descriptor class="A" table="tableA">
<field-descriptor name="idA" column="ID" jdbc-type="BIGINT" primarykey="true"
autoincrement="true"/>
<field-descriptor name="attribute1_A" column="a1" jdbc-type="VARCHAR"/>
<field-descriptor name="attribute2_A" column="a2" jdbc-type="VARCHAR"/>
...
<collection-descriptor name="listOfA" element-class-ref="A"
auto-retrieve="true" auto-update="true" indirection-table="tableA_A">
<fk-pointing-to-this-class column="idA"/>
<fk-pointing-to-element-class column="idA"/>
</collection-descriptor>
</class-descriptor>
you can getCollection of A where listOfA contain at lesat one element equal to
wantedAInstance :
crit.addEqual("listOfA",wantedAInstance);
getCollectionbyCriteria(A.class,crit);
you can getCollection of A where listOfA contain at lesat one element A having at
least A in his listOfA collection :
crit.addEqual("listOfA.listOfA",wantedAInstance);
getCollectionbyCriteria(A.class,crit);
...
is it your goal ?
----- Original Message -----
From: Joe Germuska
To: OJB Users List
Sent: Thursday, October 02, 2003 12:00 AM
Subject: Queries for M:N collections?
At 16:44 -0500 10/1/03, Joe Germuska wrote:
>I'm dealing with a case where I want to model an M:N relationship
>between two objects of the same type. I have a collection
>descriptor modeled off of the example for this on the OJB site.
>When I go to store, I'm getting a class cast exception...
For what it's worth, changing that property to a Collection
definitely solved my problem. Which leads me to the real question:
I need to construct a Query which selects collections for either
direction of this relationship. That is, Given a parent, I need to
find all of its children, and given a child, I need to find all of
their possible parents.
I can probably work this out with a QueryBySQL, but I'm trying to
avoid that. I don't see any methods on Criteria to set where I can
set something like "property contains some member"... Can anyone
advise?
Thanks in advance,
Joe
--
Joe Germuska
[EMAIL PROTECTED]
http://blog.germuska.com
"We want beef in dessert if we can get it there."
-- Betty Hogan, Director of New Product Development, National
Cattlemen's Beef Association
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.522 / Virus Database: 320 - Release Date: 01/10/2003
