one-to-many mappding ignoring foreign key

gino · **Joined:** Mon Jun 26, 2006 4:19 am **Posts:** 3

I have posted this question in the NHibernate forum a few days ago, but since it's not .Net specific (in my opinioin) I'm posting it here again, hoping I will get more feedback.

Here's what I have: a ResourceString table with an Id (not very meaningful) and a ResourceId (Guid) which forms a secundary key with the field IsoLangCode.
Most entity tables (like 'Model' in the example below) link to this resource table with a XxxResId field.

The following hbm.xml contains a on-to-many mapping for a property called Descriptions in the Model class.

Code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
    <class name="X.Core.Data.Model, X.Core.Data" table="model" lazy="false">
        <id name="Name" column="`Name`" type="String">
            <generator class="assigned" />
        </id>
        <property name="DescriptionResId" type="Guid" />

        <bag name="[b]Descriptions[/b]" table="ResourceStrings" lazy="false" >
            <key column="ResourceId" foreign-key="DescriptionResId" />
            <one-to-many class="X.Core.Data.ResourceString, X.Core.Data" />
        </bag>
        <bag name="Features" table="Model2Feature" lazy="false">
            <key column="ModelName" />
            <many-to-many class="X.Core.Data.Feature, X.Core.Data" column="FeatureName" />
        </bag>
    </class>
</hibernate-mapping>

As you can see, I have set 'DescriptionResId' as the foreign-key. When I run my getter-code I get an exception, though. I've noticed that the generated SQL is OK, except for the where clause parameter. The parameter is assigned the Name of the Model instance (the PK of the Model table) and not the DescriptionResId I asked NHibernate to use.

Looking at the NHibernate source made me suspect that the foreign-key attribute is ignored for one-to-many (and simpel collection mapping) mappings... (N)Hibernate will always use the PK.

Am I correct, or just missing the obvious?

Thanks,

G.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

foreign-key is the wrong attribute. You want property-ref. Note that property-ref takes the name of the hibernate property in question, not the DB column name.

Have a glance at the ref docs for what foreign-key does.

gino · **Joined:** Mon Jun 26, 2006 4:19 am **Posts:** 3

Thanks for your reply!

I jus tried it out, but got an exception stating: The 'property-ref' attribute is not declared. Which was what I expected, since the xsd didn't allow it in the first place. Appearantly, the property-ref attribute can be used in a one-to-one tag, not in a one-to-many.

I'm a real newbie when it comes to (N)Hibernate and having a hard time to believe that what I'm trying to accomplish is not possible - it's not like I'm doing something extra-ordinary here.

Maybe I should use a whole other approach?

G.

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

property-ref goes on <key>, not <one-to-many>. I had a look in the Hibernate 2.1 DTD (I think that's equivalent to what's used by NHibernate) and it's not there, so I guess that this is an Hibernate 3 feature. Looks like you're out of luck, sorry..