Re: Only the last object semi ok when executing oql query

[Armin Waibel]

Hi,
Stijn de Witt wrote:
Thanks for your message, it clears up a lot.
I guess I'll use the PB api then. 
Do you know if/when this will be fixed 
for ODMG?
I will try to fix this, but I can't give a time frame when it will 
happen (much other stuff to do).


Thanks for your responses to all the little questions too. If have some 
new in reaction to your answers, please read below...

Armin Waibel wrote:
Hi Stijn,
at the end of writing this mail I found that you are using 
"inheritance hierarchy to multiple joined tables" for Candidate. The 
ODMG-api doesn't work properly with this feature (PB-api does, sorry 
this was only noted in 1.0.1 release-notes). Additionally you define 
in Person class-descriptor Candidate as extent class. Mixing these 
features doesn't make sense (think so). So remove the the 'super' 
reference in Candidate and only use 'extent' the feature to tell OJB 
about the hierarchy.

Can you explain the part about the extent and super a bit more?s
With extent-class attribute you can declare object hierarchies
http://db.apache.org/ojb/docu/guides/advanced-technique.html#Extents+and+Polymorphism
Declare tags for Person and Candidate independently (all fields declared 
in Person have to be declared in Candidate too). Then xdoclet automatic 
creates an extent-class entry in Person
http://db.apache.org/ojb/docu/guides/xdoclet-module.html#ojb.extent-class

Now you can query for all Person.class and OJB will return a Collection 
of all Person and Candidate objects.

If you use the "super" reference (declare all field again in both 
classes) the DB "sub"-table only contain the PK,FK column and the 
additional columns for the sub-class ('determine-extents' should be set 
false in super class).
If you query for all Person.class OJB will return a Collection of Person 
objects containing all Person objects and the Person part of all 
Candidate objects (but AFAIK no Candidate objects). If you query for 
Candidate OJB return a Collection of Candidate objects by read data from 
both tables.

regards,
Armin

I am 
using OjbDoclet. Here are the xdoclet comments for Person and Candidate:

/**
* @ojb.class table="bit_Person"
*/
public class Person
{
   /**
   * @ojb.field name="id"
   * primarykey="true"
   * jdbc-type="INTEGER"
   * length="11"
   * autoincrement="ojb"
   */
   protected int id;
/**
* @ojb.class table="bit_job_Candidate"
* include-inherited="false"
* @ojb.reference class-ref="nl.bergland.codamo.Person"
* name="super"
* foreignkey="id"
* auto-retrieve="true"
* auto-update="true"
* auto-delete="true"
*/
public class Candidate extends Person
{
   /**
    * @ojb.field name="id"
    * primarykey="true"
    * jdbc-type="INTEGER"
    * length="11"
    * autoincrement="ojb"
    */
   protected int id;
I am worried about the id field too. It's duplicated in Candidate, but 
that shouldn't be necessary should it?

Greetings,
-Stijn
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