I have a scenario that doesn't seem to exotic, but I can't find the answer, so I'm hoping that someone can help. I have two entities that I want to map together in a one-to-many relationship.

My containing entity has an integer primary key, but it also contains three other columns that act as a foreign key to my second entity, which has a compsite key made up of those three columns:

Class A
<class name="Calls" table="Calls" >
<id name="CallID" column="CallID" type="Int32" unsaved-value="0">
<generator class="identity" />
</id>
<property name="Location" column="Location" type="String" length="25" />
<property name="CustID" column="CustID" type="Int32" length="4" />
<property name="Library" column="Library" type="String" length="50" />
...
</class>

Class B
<class name="Calls_l" table="Calls_l" >
<composite-id>
<key-property name="CustID" column="CustID" type="Int32" length="4" />
<key-property name="Location" column="Location" type="String" length="25" />
<key-property name="Library" column="Library" type="String" length="50" />
</composite-id>
...
</class>

All I want to do is to create a bag of Bs in A, but the mapping expects the foreign key in B to map to the primary key in A. For example, this:

<bag name="Locations" >
<key>
<column name="Library"/>
<column name="Location"/>
<column name="CustID"/>
</key>
<one-to-many class="Calls_l"/>
</bag>

yields the following exception:

"Foreign key in Calls_l must have the same number of columns as referenced primary key in table Calls."

The problem is that I don't WANT to reference the primary key in Calls.
Yes, this problem seems stupid to me too. Can someone point me in a direction??

Thanks for the response. I had tried this before, and confirmed again that "properties" doesn't seem to be a valid element under the class namespace. It throws the following exception when the configuration loads the assembly:

"The element 'class' in namespace 'urn:nhibernate-mapping-2.0' has invalid child element 'properties' in namespace 'urn:nhibernate-mapping-2.0'. List of possible elements expected: 'urn:nhibernate-mapping-2.0:discriminator urn:nhibernate-mapping-2.0:version urn:nhibernate-mapping-2.0:timestamp urn:nhibernate-mapping-2.0:property urn:nhibernate-mapping-2.0:many-to-one urn:nhibernate-mapping-2.0:one-to-one urn:nhibernate-mapping-2.0:component urn:nhibernate-mapping-2.0:dynamic-component urn:nhibernate-mapping-2.0:any urn:nhibernate-mapping-2.0:map urn:nhibernate-mapping-2.0:set urn:nhibernate-mapping-2.0:list urn:nhibernate-mapping-2.0:bag urn:nhibernate-mapping-2.0:idbag urn:nhibernate-mapping-2.0:array urn:nhibernate-mapping-2.0:primitive-array urn:nhibernate-mapping-2.0:subclass urn:nhibernate-mapping-2.0:joined-subclass'

Is this a Java Hibernate-only tag? Do I need a special reference in my assembly? I am using NHibernate v. 1.20 Alpha.

Yes, properties isn't in the hibernate2 mapping DTD. Can you play with your schema? You could add a join table to get around this, then map this as a many-to-many (that happens to be a one-to-many, but H2 doesn't have unique="true" on many-to-many). The join table would have the CallID, Location, CustID and Library columns from the Calls table.

There are other things that you can do to get this working, but they all involve tweaking your schema or upgrading to java. Which do you prefer? ;>

A Faustian choice!! Unfortunately, doing either would be very difficult at this point. It looks like I may have to punt: as a workaround, I was using HQL to get enumerable sets of the classes, and then "assembling" them in the DAO before returning the entity. This seems to defeat the composition that NHibernate affords - does anyone have any better ideas??