imo you can solve it with the help of a subquery referencing the enclosing query. please have a look at QueryTest#testSubQuery4().
hth jakob
Coup, Robert Muir wrote:
Hi,
One problem solved - one to go.
GO is a group. A group has a collection of members (which is a
superclass of group), and has a collection of all groups that contain
it, and has a reference to RO. RO
+ GO
+ MO
+ MO
+ MO
+ MO
+ MO
+ GO
In retrieving the groups in RO, I need to get only those groups where GO.groupsThatContainMe.size() == 0.... Ie. Where there are no parent groups for this one.
How can I specify this using a PB Query in my QueryCustomizer?
Thanks again for all your help,
Robert
-----Original Message-----
From: Jakob Braeuchi [mailto:[EMAIL PROTECTED] Sent: Thursday, 15 January 2004 7:27 a.m.
To: OJB Users List
Subject: Re: Qualified Collection Relationships
hi robert,
you can solve this problem by using a QueryCustomizer to add additional criteria to the query generated by ojb.
hth jakob
Coup, Robert Muir wrote:
Hi All,
What I have :
Root Object RO has:
- a collection of CO objects specified using
<collection-descriptor>
Child Object CO has:
- a collection of CO objects specified using
<collection-descriptor>
- a reference to a parent CO (null if the object has no CO parent) - a reference to the RO
Example...
RO
+ CO
+ CO
+ CO
+ CO
+ CO
+ CO
+ CO
+ CO
However, when my collection of CO's for the RO is built by OJB on retrieval, it does something like:
SELECT * FROM co WHERE co.RO_reference = RO.id
This returns all the CO objects, but I only want the direct
children
such as:
SELECT * FROM co WHERE (co.RO_reference = RO.id) AND
(co.CO_parent
= null)
Which I would ideally declare something like:
<collection descriptor name="COTree"
element-class-ref="CO"
auto-retrieve="true"
auto-update="false"
>
<inverse-foreignkey field-ref="RO_reference"/>
<inverse-criteria field-ref="CO_parent" value="null"/> </collection-descriptor>
I searched the mail archives and came up with some posts
saying that
qualified relationships were on the todo list in February
2003... Has
there been any progress since then?
Alternatively, how have other people solved this? Setting auto-retrieve to false and doing a getCollectionByCriteria() in the PersistenceBrokerAware afterLookup() method seems like a reasonable option, but means the business object layer starts to know a little bit much about the persistence mechanisms...
Thanks for your help,
Robert Coup :)
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