NHibernate.Mapping.Attributes and derived properties

Poseidon · **Joined:** Sun Aug 20, 2006 8:09 pm **Posts:** 8

Hi !
I use nhibernate 1.2 CR 1 with the one-table-per-concrete-class mapping paradigm. I want to use NHibernate.Mapping.Attributes to auto-generate mapping files. The problem is, that for inherited properties from base classes, no mappings will be generated. Only for the properties defined in the current class the mappings are created by NHibernate.Mapping.Attributes.

An example:

Code:

    [Class]
    public class PersistenceBase
    {
        private int persistenceId;

        [Id]
        public virtual int PersistenceId
        {
            get { return persistenceId; }
            set { persistenceId = value; }
        }
    }

    [Class]
    public class Child: PersistenceBase
    {
        private string name;

        [Property()]
        public virtual string Name
        {
            get { return name; }
            set { name = value; }
        }
    }

The output xml is:

Code:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="HiberTest.PersistenceBase, HiberTest">
    <id/>
  </class>
  <class name="HiberTest.Child, HiberTest">
    <property name="Name" />
!! ID would be needed here
  </class>
</hibernate-mapping>

Is there a way to enable NHibernate.Mapping.Attributes to also map the inherited fields to child-classes ?

Thanks for your help.
Thomas

devonl · **Posted:** Tue Mar 13, 2007 8:33 pm

i don't use Attributes, but wouldn't

Code:

[Class]
public class Child: PersistenceBase
{

be something like:

Code:

[Subclass]
public class Child: PersistenceBase
{

if I were writing the mapping files by hand, it would look something like:

Code:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="HiberTest.PersistenceBase, HiberTest">
    <id/>
  </class>
  <subclass name="HiberTest.Child, HiberTest">
    <property name="Name" />
</hibernate-mapping>

(doing it from memory so might not be 100% correct...)

-d

Poseidon · **Joined:** Sun Aug 20, 2006 8:09 pm **Posts:** 8

This mapping with <subclass> can be used if you want to have one table for all of your inheritance tree. But I use <class> tags for every of my classes ( no matter where they are within the inheritance tree) and I have a seperate table for each concrete class.

Thomas

devonl · **Posted:** Wed Mar 14, 2007 9:03 pm

right, i meant <joined-subclass> sorry about that. i use a combination of table-per-class-hierarchy and table-per-subclass.

KPixel · **Posted:** Sun Mar 18, 2007 8:36 am

NHMA does include mapping from base classes.
However, it stops when the base class is also mapped.

In your case, is PersistenceBase an entity ?
Do you load/save instances of this class ?

If you remove its attribute [Class], then you will have the Id in the mapping of the Child class.