joined subclasses - theoreticat question

bimki · **Posted:** Tue Mar 08, 2005 11:59 am

Hibernate version: 3.0 rc 1

Hi,

I have small theoretical question :

Is it possible to have one-to-one association between two joined subclasses? If it is possible, please show me some mapping file content. I tried to do this, but I always got errors.

my post is quite similar to http://forum.hibernate.org/viewtopic.php?t=936631

thanks in advance,

greetings
Bimki

gavin · **Posted:** Tue Mar 08, 2005 12:16 pm

Sure, just use a normal one-to-one foreign key association. Refer to the HB3 user manual for instructions.

bimki · **Posted:** Wed Mar 16, 2005 12:48 pm

Please, give me an example. I tried to do it various ways. here You have example simple code :

Code:

<class name="A" table="A">
    
    <id name="id" column="ep_id" type="integer" unsaved-value="null">
      <generator class="increment" />
    </id>      
    <property name="typ" column="ep_typ" type="string" length="10" />
    <property name="data" column="ep_data" type="date" not-null="true" />
      
    <joined-subclass name="AB" table="AB">
      <key column="cza_id" />
      <property name="x" column="cza_x" type="integer" not-null="true" />
    </joined-subclass>

    <joined-subclass name="AC" table="AC">
      <key column="czz_id" />      
      <!--one-to-one name="dokument" class="AB" foreign-key="cza_id"/-->
    </joined-subclass>

</class>

bimki · **Posted:** Sun Apr 24, 2005 5:48 pm

I tried i.e something like this :

Code:

    <joined-subclass name="AC" table="AC">
      <key column="czz_id" />     
            .................

            <property name="AB" column="ab_id" type="integer"/>

            <one-to-one name="glownaAtomowa" class="AB"/>

    </joined-subclass>

but I got class-cast exception :(

I don't know where to put foreign key, You've written about...

Lmichasz · **Posted:** Sun Apr 24, 2005 6:14 pm

In Hibernate 2.1 I would do this like this:

In AB:

<one-to-one name="ac" class="AC" property-ref="ab"/>

In AC:

<many-to-one name="ab" class="AB" column="AB_ID" unique="true"/>

PS: Pozdrowienia, tez jestem z Wrocka :)

bimki · **Posted:** Sun Apr 24, 2005 6:31 pm

At last problem is solved!

Thanks, it works!!

ps. Pozdrowionka :)