I've got a base class for my entity classes where the object's id is placed. I cannot understand how to map this. Is this even possible?

/R

You would map it as if the Id was in your derived class - because it is, essentially.

IOW, if BaseObject has an Id property and Emp extends BaseObject then you would just map Emp as if you defined Id on Emp.

benster

I create a mapping file to my base class as usual, then I add a <subclass> element with a discriminator-value attribute for each derived class. This is using a "table-per-class" hierarchy as described on page 99 of the Hibernate in Action book and in the documentation.

The Id is mapped as usual, as well as all properties in the base class. Unique fields for the sub-classes would be mapped under the appropriate <subclass> element.