Hibernate version: 3.2
Mapping documents: See below
Name and version of the database you are using: MySQL 5.0

Hi all - I have been using Hibernate for about 3 weeks now and am very impressed. However, I have run into a small problem which is causing me some issues - I have searched the forums and the web and cannot find an answer so I would be grateful if someone could point me in the right direction.

The problem is that my primary keys are being regenerated each time I update the database - this is causing me issues as I have no natural identifier and therefore one of the assumptions of my application is that the primary keys will not change. Below is the sample of my Party mapping document. I am using Hibernate Tools to generate both my schema and code.

This is the secnario - I create a new Vendor (a subclass of Party) and save it. I then add some Services to this Vendor and save them. They are persisted succesfully however the PartyID (primary key of my Party record) has been updated to a new value (MAX KEY + 1).

How can I prevent my primary keys from being updated?

Thanks in advance,

mark


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.mycompany.model">
<class name="Party" table="t_party">
<meta attribute="class-description">
</meta>
<id column="party_id" name="partyID" type="int">
<meta attribute="scope-set">protected
</meta>
<generator class="native"/>
</id>
<property column="company_name" name="companyName" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="title" name="title" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="first_name" name="firstName" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="last_name" name="lastName" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="gender" name="gender" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="email" name="email" not-null="true" type="string">
<meta attribute="field-description"/>
</property>
<property column="phone" name="phone" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="mobile" name="mobile" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="fax" name="fax" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<map name="addresses" cascade="all">
<meta attribute="field-description">Addresses for this party
</meta>
<key column="party_id"/>
<map-key column="address_type" type="string"/>
<one-to-many class="Address"/>
</map>
<many-to-one class="User" column="user_id" name="user" not-null="false" unique="true" cascade="all"/>
<joined-subclass name="Vendor" table="t_vendor">
<key column="vendor_id"/>
<property column="short_description" name="shortDescription" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="long_description" name="longDescription" not-null="false" type="text">
<meta attribute="field-description"/>
</property>
<property column="website" name="website" not-null="false" type="string">
<meta attribute="field-description"/>
</property>
<property column="active" name="active" not-null="false" type="yes_no">
<meta attribute="field-description"/>
</property>
<set name="services" cascade="all">
<meta attribute="field-description">Services offered by this vendor
</meta>
<key column="vendor_id"/>
<one-to-many class="VendorService"/>
</set>
</joined-subclass>
</class>
</hibernate-mapping>

On further investigation I discovered that my keys were not being regenerated, but rather my update method was inserting new rows into the database. The problem was that I was retrieving an Object from the database, closing the session, displaying it in the UI, and then opening a new session and calling session.save(object) to write it back to the database. Changing session.save(object) to session.saveOrUpdate(object) fixed my problem. Unfotunately, the book I used to learn Hibernate did not give examples of using saveOrUpdate but this was explained in detail in the Hibernate documentation.