How to map a list in an auxiliary/joined table?

den-javamaniac · **Joined:** Tue Dec 08, 2009 8:03 am **Posts:** 6

Hi. I'm trying to develop a simple 'Not a hello world' app using Hibernate from an existing database and I can't figure out how to manage o/r mapping.

So I have two classes Task and Tag which resemble basic id and title fields. In addition Task has a List<Tag> tags field. Here I need to map tags field in an auxiliary table. So DB should have three table: TAG, TASK, TASK_TAG. Like this:

Code:

TASK
task_id<<PK>>
task_title

TAG
tag_id<<PK>>
tag_title

TASK_TAG
task_id  <<FK>><<PK>>
tag_id <<FK>><<UNIQUE>>

Can any one help me with that issue? I would appreciate any help. Thanks in advance.

den-javamaniac · **Joined:** Tue Dec 08, 2009 8:03 am **Posts:** 6

So I figured out that the missing part was as follows:

Code:

<!-- Tags mapping needed -->
        <list name="tags" table="task_tag">
         <key column="task_id"/>
         <list-index base="0"/>
         <many-to-many column="tag_id" class="com.raccoon.core.persistence.model.Tag"/>
      </list>

But since list persists element's positions I get next column structure of table TASK_TAG:

realm_id
tag_id
idx

Can any one tell me how to get rid of idx column? Maybe by using another data type (java) like collection?