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travism
 Post subject: unidirectional one-to-many accociation on foreign key exampl
PostPosted: Thu Jun 30, 2005 12:01 pm 
Newbie

Joined: Tue Jun 28, 2005 11:11 am
Posts: 13
Location: St. Louis, Missouri, USA
Maybe it's just me, but I'm finding the xml mappings for Hibernate to be impossible. If someone could help out with this example, I'd be grateful.

I have two tables
AREA(area, area_id) -- They key is the whole row
DISTRICT (district_id, area_id, district) -- They key is the whole row

My pojo District object wants to know it's district_id, area_id, district, and the corresponding area to its area_id.

The sql would be something like:
Code:
Select district.district_id, district.district_name, district.district_area_id, area.area from AREA area, DISTRICT district  where area.AREA_ID = district.district_area_id and district_id = ?


I don't want to fuss with an Area object but would rather just query that AREA table for this one field. I believe this is a unidirectional one-to-many association on a foreign key. I'm not sure how to go about this with Hibernate since my "keys" are "composite" and I'm not doing a join.

Any ideas?
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travism
 Post subject:
PostPosted: Thu Jun 30, 2005 2:43 pm 
Newbie

Joined: Tue Jun 28, 2005 11:11 am
Posts: 13
Location: St. Louis, Missouri, USA
Is it possible to use a <formula> in an xml that will allow me to do what I want? I'd like that DistrictBO.area_id to reference the value area_id which is defined in this class but I don't know how to do that...
Code:
<hibernate-mapping>
<class name=".test.bo.DistrictBO" table="F_DISTRICT">
<id name="id" type="string" column="DISTRICT_ID" >
   <generator class="assigned"/>      
</id>
<!-- A cat has to have a name, but it shouldn' be too long. -->
<property name="area_id"
   column="DISTRICT_AREA_ID"
/>
<property name="name"
column="DISTRICT_NAME"
/>
      
<property name="areaName" type="string">
<formula>
( select F_AREA.AREA from F_AREA WHERE F_AREA.AREA_ID = DistrictBO.area_id )
</formula>
</property>
      
</class>
</hibernate-mapping>
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tenwit
 Post subject:
PostPosted: Mon Jul 18, 2005 11:11 pm 
Expert
Expert

Joined: Thu Dec 23, 2004 9:08 pm
Posts: 2008
Leave out the DistrictBO bit:
Code:
<hibernate-mapping>
<class name=".test.bo.DistrictBO" table="F_DISTRICT">
   <id name="id" type="string" column="DISTRICT_ID" >
     <generator class="assigned"/>     
  </id>

  <property name="area_id" column="DISTRICT_AREA_ID"/>
  <property name="name" column="DISTRICT_NAME"/>
     
  <property name="areaName" type="string">
    <formula>
      ( select F_AREA.AREA from F_AREA WHERE F_AREA.AREA_ID = area_id )
    </formula>
  </property>
     
</class>
</hibernate-mapping>


Attributes with no table qualifier are assumed to refer to the table being loaded.
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