Hi,

I have a Master - Detail relationship, where there are many different types of details (necessitating specialization). The Master points forward to its Details (I'd like to keep it that way - bidirectionality isn't an option). I need to associate some identifier with each detail record, and store it in the Master - which is naturally a map.

The problem is, when I try to add something to the Master map, I get this exception:

java.lang.RuntimeException: net.sf.hibernate.HibernateException: SQL insert, update or delete failed (row not found)

I turn on P6SPY and I notice that Hibernate is trying to execute an update statement on the Detail table with the index value I'm assiging along with the rest of the Detail record. Why is it deciding to try an update? How do I signal to Hibernate that it should be doing an insert?

Thanks, Steve

Mappings follow.

<hibernate-mapping>
<class name="Detail">
<id name="key">
<generator class="assigned"/>
</id>
<discriminator column="TYPE"/>

<subclass name="SomeDetail" discriminator-value="S">
<property name="name"/>
</subclass>
<subclass name="AnotherDetail" discriminator-value="A">
<property name="serial"/>
</subclass>
</class>
</hibernate-mapping>

<hibernate-mapping>

<joined-subclass name="Master" extends="Super">
<key column="SUPER_ID"/>

<map name="detailMap">
<key column="DETAIL_ID"/>
<index column="MASTER_TO_DETAIL_ID" type="long"/>
<one-to-many class="Detail" />
</map>
</joined-subclass>

</hibernate-mapping>

The problem is that you have not specified an appropriate "unsaved value" for your defined id. The default value is "null", which means that any value other than a null will result in an update, rather than an insert because it is not "unsaved". Check out the options http://www.hibernate.org/hib_docs/reference/en/html/mapping.html#mapping-declaration-id and see which one works best for your situation. But this seems to get hairy with assigned ids...

My suggestion: if at all possible, move the id generation logic into an IdentifierGenerator implementation and have Hibernate manage that piece for you.

Thanks Steve, that makes a lot of sense...

We're using "assigned" for now for other reasons (we have another in-memory persistence system that we use as our backing store for some of our unit tests). I'm wary of "assigned" though, if it becomes a problem we'll definitely look at IdentifierGenerator.

Regards,
Steve