Hibernate version: 3.0.5

Mapping documents:

<class lazy="true" entity-name="BusinessObject" table="BusinessObject">
<composite-id name="_id" class="de.companio.f5.persistence.CompositeId">
<key-property name="id0" type="string" column="BOBJID"/>
</composite-id>
...
</class>

The BusinessObject entity uses a dynamic model. Therefore a Map is returned when a BusinessObject entity is loaded.

Yet, this map contains a HashMap for the "_id" key. In other words: the class that is specified for the composite-id is not instantiated.

(The HashMap that is returned for the "_id"-key contains an entry for "id0".)

Looking at the source code of hibernate 3.0.5 I found the following lines in TuplizerLookup:

public static TuplizerLookup create(Component component) {
PersistentClass owner = component.getOwner();

Tuplizer dmt = new DynamicMapComponentTuplizer(component);

Tuplizer pt = owner.hasPojoRepresentation() && component.hasPojoRepresentation() ?
new PojoComponentTuplizer(component) : dmt;

Tuplizer d4jt = owner.hasDom4jRepresentation() ?
new Dom4jComponentTuplizer(component) : null;

return new TuplizerLookup(pt, dmt, d4jt);
}

It seems that composite ids (i.e. components) are never tuplized into PoJos if their owner has not a PoJo representation.

Is there a reason for this behaviour?

Um. Sounds like very reasonable behavior to me....

I have a "dynamic" composite-id class that fits all my dynamic entities and that I would like to be instantiated.

The problem I see is that equals and hashCode do not work with "HashMap"-ids. In the Hibernate documentation I read that it is important for composite id classes to implement these methods. That's the reason why I implemented a "dynamic" composite-id class.

Wouldn't it be possible to have the composite-id classes instantiated if the "class" attribute is explicitly set?

Is there anybody out there who can resolve my concerns?

In other words, is it not necessary for dynamic models that there composite ids have equals and hashCode implemented based on the value of the key fields?

I got it! A map is a perfect composite id because equals and hashCode is specified to be basec on the values of the map.