I'm using Hibernate 3.3.1GA.

My problem is I have a parent class, with a map of child objects. The child objects have relation to another object. I need the index in the map to be a property of the child object's relation property. For instance:

public class Parent {
Map<String, Child> getChildren() {...}
}

public class Child {
public SomeOtherObject getOtherObject() {...}
}

public class SomeOtherObject {
public String getName() {...}
}

I want the index in the children map property on the Parent object to be the name property on the SomeOtherObject. Is this possible?

Can you post the relevant mappings

<class catalog="someDB" name="Parent" table="Parents">
...
<map cascade="all" catalog="someDB" lazy="true" name="children"
sort="unsorted" table="Children">
<key column="ParentID"/>
<key column="Name"/>
<one-to-many class="Child"/>
</map>
</class>

<class catalog="someDB" name="Child" table="Children">
...
<many-to-one class="SomeOtherObject" column="OtherObjectID" name="otherObject"/>
</class>

<class catalog="someDB" name="SomeOtherObject" table="OtherObjects">
...
<property generated="never" lazy="false" name="name" type="string">
<column name="Name" not-null="true" />
</property>
</class>

I figured it out using a formula:

<map cascade="all" catalog="someDB" lazy="true" name="children"
sort="unsorted" table="Children">
<key column="ParentID"/>
<map-key column="Name" formula="(select o.Name from OtherObjects o where o.OtherObjectID = OtherObjectID) as Name"/>
<one-to-many class="Child"/>
</map>
</class>