Hi,

I have a strange situation in my Hibernate application:

I have a class Person, which has a field called Representant. Representant may be sometimes null and if it is not - representant id is always the same as person's id.


class Person {
...
private Representant representant;
...
}

in my hbm.xml file this association is defined as:

<class name="org.dyndns.orzekanie.Person" table="PERSONS">
<id name="id">
<generator class="native"/>
</id>
...
<one-to-one name="representant" class="org.dyndns.orzekanie.Representant" lazy="false" cascade="all"/>
</class>

class Representant is defined as:

<class name="org.dyndns.orzekanie.Representant" table="REPRESENTANTS">
<id name="id">
<generator class="assigned"/>
</id>
...
</class>


the problem is that where i try to save a person (session.save(person)) as a new record in the database, the representant id is not initialized - so it ends with
org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save()

I thought I can do something like that:

<class name="org.dyndns.orzekanie.Person" table="PERSONS">
<id name="id">
<generator class="foreign">
<param name="property">representant</param>
</generator>
</id>
...
<one-to-one name="representant" class="org.dyndns.orzekanie.Representant" lazy="false" cascade="all"/>
</class>

<class name="org.dyndns.orzekanie.Representant" table="REPRESENTANTS">
<id name="id">
<generator class="native"/>
</id>
...
</class>

but the representant may be sometimes null so when I save the person with null representant it would be impossible to get an id.

I have no idea how I should implement my hibernate associations. Could anyone give me some advices?

Thanks,
Pawel


Hibernate version: 3.2.24

Mapping documents:

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:

Name and version of the database you are using: MySQL 4.1

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

Thanks. I read chapter you'd mentioned more carefully than before and I've found a solution:


<class name="org.dyndns.orzekanie.Person" table="PERSONS">
<id name="id">
<generator class="native">
<param name="property">representant</param>
</generator>
</id>
...
<one-to-one name="representant" class="org.dyndns.orzekanie.Representant" lazy="false" cascade="all"/>
</class>

<class name="org.dyndns.orzekanie.Representant" table="REPRESENTANTS">
<id name="id">
<generator class="foreign">
<param name="property">person</param>
</generator>
</id>
...
<one-to-one name="person" class="org.dyndns.orzekanie.Person" constrained="true"/>
...
</class>


The thing is that I should add Person class to my Representant class. It makes no sense for me but it does not prevent in any case. "constrained" property tells hibernate the order in which it should get/update/save objects.

Pawel

Thought I'd bump this up - not sure how to rate it... This is a good post.

Posting my redacted mapping files just for another example