how to create a custom JoinedSubclassEntityPersister

David.chau · **Joined:** Fri Sep 22, 2006 4:17 am **Posts:** 10

Hibernate version: 3.2

Mapping documents:
<class table="TSRFGEOILOT" name="GeometrieIlot"> 
<id column="idIlotGeo" name="idIlotGeo" type="string">
<generator class="assigned"/>
</id>

<one-to-one name="ilotSurface" class="IlotDeclare" constrained="true"/>

<joined-subclass name="GeometrieIlotMetropole" table="TSRFILOTGEOMETROPOLE">
<key column="idIlotGeo"/>
<property column="geometrie" name="geometrie" type="string"/>
<property column="objectid" name="objectid" type="string"/>
</joined-subclass>

<joined-subclass name="GeometrieIlotGuyane" table="TSRFILOTGEOGUYANE" >
<key column="idIlotGeo"/>
<property column="geometrie" name="geometrie" type="string"/>
<property column="objectid" name="objectid" type="string"/>
</joined-subclass>

<joined-subclass name="GeometrieIlotReunion" table="TSRFILOTGEOREUNION" >
<key column="idIlotGeo"/>
<property column="geometrie" name="geometrie" type="string"/>
<property column="objectid" name="objectid" type="string"/>
</joined-subclass>

<joined-subclass name="GeometrieIlotAntilles" table="TSRFILOTGEOANTILLES" >
<key column="idIlotGeo"/>
<property column="geometrie" name="geometrie" type="string"/>
<property column="objectid" name="objectid" type="string"/>
</joined-subclass>
</class>

Name and version of the database you are using:Oracle 10g

Hi,
I would like to create a custom persister for this mapping.
My questions are:
Where do I declare my persister (in my class tag or my subclasses tags)?
How to implement me persister?

thanks in advance

steckemetz · **Posted:** Tue Dec 12, 2006 8:21 am

The easiest way to implement such a persister is copy-and-paste!
Thats certainly ugly. You have to modify the copied code until
it meets you needs.

If I remember subclassing of a persister wasnt possible.
At least in 3.1.

Configuration can be done in class and subclass tags, e.g.:

Code:

   <class name="baseclass"
      table="mytable" discriminator-value="null"
      persister="basepersister"
      lazy="false">
...
   <joined-subclass name="myclass"
      extends="baseclass"
               persister="mypersister">
...

BTW, why do you need a custom persister ?

David.chau · **Joined:** Fri Sep 22, 2006 4:17 am **Posts:** 10

In fact, I use a GIS with my database.

I store a geometry object in the column "geometrie" but I my code, I retrieve a WKT representing the geometry.
To do that, I made a GeometryPersister with a SigneTableEntityPersister.

Now I have the last mapping and I have to do the same thing so I thought that was the way to do.

max · **Posted:** Tue Dec 12, 2006 10:19 am

and why is usertypes not enough for you ?

David.chau · **Joined:** Fri Sep 22, 2006 4:17 am **Posts:** 10

We tried to do a usertype but we did not success and we did not find anough help.
I found this way because in the SELECT statement my string is generated by a GIS function (ST_ASTEXT) and and in the INSERT or UPDATE statement, the ST_GEOMETRY function is called.

max · **Posted:** Tue Dec 12, 2006 12:51 pm

David.chau wrote:

We tried to do a usertype but we did not success and we did not find anough help.

did you try jboss support ? :)

Quote:

I found this way because in the SELECT statement my string is generated by a GIS function (ST_ASTEXT) and and in the INSERT or UPDATE statement, the ST_GEOMETRY function is called.

ok - this can be done by using custom sql (e.g. <sql-xxx>)

This is actually a requst I see more and more...what parts did you actually have to change in the persister do it succesfully ? Maybe we should add explicit support for it.

steckemetz · **Posted:** Wed Dec 13, 2006 4:30 am

Hi Max,

we have some similar issues, which could only be solved by
modifying the mapping in the already read configuration object.
You can find the complicated details in the jboss support issue:
00009937 bad performance using CLOBs with DB2

Thanks,
Barthel

max · **Posted:** Wed Dec 13, 2006 6:59 am

yes, I remember your case and both usecases are relevant.

Yours is for performance issues where as David.chau is about getting the proper semantics of his GIS data, correct ?

David.chau would there be anything lost for you if just read in the actual value in the db and let a usertype handle the conversion back and forth ? Or is that conversion complex/heavy ?