Mapping multiple sets to one table

chris103 · **Posted:** Wed Dec 01, 2004 8:01 am

Hi,

I wonder if the following is possible within hibernate. Within my Object model I have a class 'EntityDescription' which stores the title and a descriptive text for a specified language for a corresponding entity. The title resp. the description are stored within a HashMap each, with the language as key.
For the relational model it seems quite convenient to me, that the sets of 'EntityDescription' are mapped to one table:

create table DESCRIPTIONS (
ENTITY_ID bigint not null,
DESCRIPTION varchar(255),
ISO_LANG_CODE varchar(2) not null,
TITLE varchar(255),
primary key (ENTITY_ID, ISO_LANG_CODE)
);

The standard SQL-operation for a new title or description is an INSERT-statement which leads to a 'Duplicate key or integrity constraint violation message'. The statement should be an update, if there exists already a row with the composite keys.
Is it possible to tell hibernate, that there are multiple sets mapped to one table? Or to I have to cope with redundancy and let hibernate manage the sets by one table for each set with exact the same key-values?

Hibernate version: 2.1.7c

Mapping documents:

Code:

<component
    name="entityDescription"
    class="com.raytion.catalog.model.EntityDescription"
>

        <map
            name="descriptions"
            table="DESCRIPTIONS"
            lazy="false"
            sort="unsorted"
            inverse="false"
            cascade="all"
        >

              <key column="ENTITY_ID"/>
              <index
                  column="ISO_LANG_CODE"
                  type="string"
                  length="2"
              />
              <element
                  column="DESCRIPTION"
                  type="string"
                  not-null="false"
                  unique="false"
              />
        </map>

        <map
            name="titles"
            table="DESCRIPTIONS"
            lazy="false"
            sort="unsorted"
            inverse="false"
            cascade="all"
        >

              <key column="ENTITY_ID"/>
              <index
                  column="ISO_LANG_CODE"
                  type="string"
                  length="2"
              />
              <element
                  column="TITLE"
                  type="string"
                  not-null="false"
                  unique="false"
              />
        </map>
</component>

max · **Posted:** Wed Dec 01, 2004 9:09 am

Don't know if the following is usable for you - but look at http://blog.hibernate.org/cgi-bin/blosx ... 06/23#i18n which is one way to handle i18n with hibernate.

chris103 · **Posted:** Wed Dec 01, 2004 9:19 am

The suggested pattern by Gavin looks quite nice, thanks for the link.

Am I right then, if I conclude from your answer that it isn't possible with Hibernate to map multiple sets to one table?

max · **Posted:** Wed Dec 01, 2004 9:38 am

hmm - well you are "splitting" up what is actually an entity/row into two distinct items.

And it would be quite inefficient do handle this - i think.

But take a look at http://www.gloegl.de/blog/archives/hibe ... e-columns/ which touches on a similar situation.

michael · **Posted:** Wed Dec 01, 2004 9:44 am

Yes, mapping a single private map and then creating two map wrappers around it would be a solution I think.

chris103 · **Posted:** Wed Dec 01, 2004 10:02 am

Yes, I understand that it's not possible for hibernate to split rows for different instances. I'll think about the wrapping approach, sounds quite nice and feasible.