Hibernate + Spring + persist one-to-one relation + empty foreign key

Question

Hello,

I am trying to persist a one-to-one relation with Spring 1.2.8 and Hibernate 3.2.7ga but the foreign key is always empty.

But let me first give you a short introduction:

I have two Entities called "ClientDomain" (Web-Domain) and "Measurement".

Hibernate Mapping Files:

ClientDomain.hbm.xml:

<hibernate-mapping package="statistics.jobs.domain">

<class name="ClientDomain" table="domains" lazy="false">

<id column="id" name="id" type="int">
  <generator class="native"/>
</id>

<property name="version" not-null="false"/>
<property name="url"/>
<property name="etrackerApiUser" column="etracker_api_user"/>
<property name="etrackerApiKey" column="etracker_api_key"/>
<property name="etrackerUsername" column="etracker_username"/>
<property name="etrackerPassword" column="etracker_password"/>

<set 
  name="measurements" 
  table="measurements" 
  lazy="false" 
  cascade="merge,save-update" 
  inverse="true">
  <key column="domain" />
  <one-to-many class="Measurement"/>
</set>   

</class>

</hibernate-mapping>

Measurement.hbm.xml:

<hibernate-mapping package="statistics.jobs.domain">

<class name="Measurement" table="measurements" lazy="false">

<id column="id" name="id" type="int">
  <generator class="native"/>
</id>

<property name="version" not-null="false"/>
<property name="time" type="java.util.Date"/>
<property name="numberOfDocuments" column="documents"/>

<one-to-one 
  name="domain" 
  class="ClientDomain" 
  cascade="merge,save-update"
/>   

</class>

</hibernate-mapping>

I am getting some statistics from various source for a domain and then want to persist them. In this way I have a history for a domain.

The ClientDomain objects are already persistent.

A Measurement object is created like so:

Measurement measurement = new Measurement();
measurement.setDomain(domain);
measurement.setTime(new Date());
measurement.setNumberOfDocuments(22222);
measurementManager.insertMeasurement(measurement);

insertMeasurement(Measurement measurement):

public void insertMeasurement(Measurement measurement) {    
  getHibernateTemplate().saveOrUpdate(measurement);
}

This is the result:

+----+---------+-----------+---------------------+--------+
| id | version | documents | time                | domain |
+----+---------+-----------+---------------------+--------+
| 82 |    NULL |     22222 | 2009-11-16 14:28:32 |   NULL |
| 83 |    NULL |     22222 | 2009-11-16 14:28:33 |   NULL |
| 84 |    NULL |     22222 | 2009-11-16 14:28:34 |   NULL |
+----+---------+-----------+---------------------+--------+

I already checked if the domain instance is correct. Everything is as it should be.

So what am I doing wrong? Why is the domain foreign key not saved along with the measurement?

What I tried so far:

• calling persist instead of saveOrUpdate (also changed cascaded to persist)
• wrapping the saveOrUpdate in a session.beginTransaction() and session.getTransaction().commit()

But so far I had no luck.

Answer 1

YOu have a one-to-many relationship from ClientDomain to measurement. But you have a one-to-one relationship from Measurement to ClientDomain.

Make the relationship in Measurement to ClientDomain a many-to-one relationship.