Hi All,

This is a question concerning a mapping file.

The Object World: Two Classes A and B, where B is a mapping between three instances of A.

class B {
A a1;
A a2;
A a3;
}

I don't want a surrogate key, but one of the mapped instances (say a1 ist the primary key)

The DB table is:

A (id, ...)
B (primary foreign key a1, foreign key a2, foreign key a3)

At the moment my mapping looks like:

<hibernate-mapping>
<class name="..B" schema="C" table="B">
<id name="a1" column="A1">
<generator class="foreign">
<param name="property">a1</param>
</generator>
</id>
<one-to-one name="a1" />
<many-to-one column="A2" name="a2" not-null="true"/>
<many-to-one column="A3" name="a3" not-null="true"/>
</class>
</hibernate-mapping>


I am far from sure that this is correct but it is the best idea I have at the moment.

When I try to insert an instance of B in the DB I get the following exception:

java.lang.ClassCastException
at org.hibernate.id.ForeignGenerator.generate(ForeignGenerator.java:50)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:91)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:544)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:533)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:529)
at com.temp.FillDB.fillDB(FillDB.java:429)
at com.temp.FillDB.main(FillDB.java:218)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:86)


What is my mistake?

Thanks a lot,

Philipp