How can i map these entiites??????

mborghi · **Joined:** Fri Feb 23, 2007 2:05 pm **Posts:** 2

CREATE TABLE [Entity]
(
[id] [int] IDENTITY (1, 1) NOT NULL ,
[name] [varchar] (50) NULL ,
[type] [varchar] (10) NULL
) ON [PRIMARY]

CREATE TABLE [EntityCompany]
(
[comp_id] [int] IDENTITY (1, 1) NOT NULL ,
[entity_id] [int] REFERENCES Entity.id
[company_type] [tinyint] NOT NULL
) ON [PRIMARY]

CREATE TABLE [EntityPerson]
(
[person_id] [int] IDENTITY (1, 1) NOT NULL ,
[entity_id] [int] REFERENCES Entity.id
[email] [varchar] (50) NULL ,
[phone] [varchar] (12) NULL
) ON [PRIMARY]

I want to map this entities in a class hierarchy using NHibernate but it seems to be impossible. I tried using <joined-subclass> but this way uses the inherited ID for the subclasses, and i want to use the subclass own ID, but also get the values of the inherited properties. Anyone knows if it is any way of achieving this? Thxs.

mnichols · **Joined:** Mon Aug 21, 2006 9:18 am **Posts:** 179

What your tables are suggesting is the Decorator pattern. So you'd wrap an Entity class within your EntityCompany and EntityPerson classes, delegating underlying properties to the inner object.
Personally, I prefer this pattern over subclassing whenever possible anyways.

Code:

public class EntityCompany : Entity
{
   private Entity _inner;
   public EntityCompany(Entity entity)
   {
      _inner = entity;
   }
   public SomeProperty
    {
       get{return _inner.SomeProperty;
    }
}

If you insist on joined-subclass approach then I believe you'll need to implement some identifier to be unique in addition to the key NHibernate uses to subclass across tables.

MIKE[/code]

rolandz · **Posted:** Sun Feb 25, 2007 5:01 pm

I think that the entitycompany and entityperson stay in many-to-one relationship with entity rather since you can have svsral insances of entyticompany as well as entityperson referencing the entity.

There is no exclusion existing that would say you have either entitycompany or entityperson but them both. Furthermore it is not an error to have more than one entityprson or entitycompany per one entity.

mborghi · **Joined:** Fri Feb 23, 2007 2:05 pm **Posts:** 2

mnichols wrote:

What your tables are suggesting is the Decorator pattern. So you'd wrap an Entity class within your EntityCompany and EntityPerson classes, delegating underlying properties to the inner object.
Personally, I prefer this pattern over subclassing whenever possible anyways.

Code:

public class EntityCompany : Entity
{
   private Entity _inner;
   public EntityCompany(Entity entity)
   {
      _inner = entity;
   }
   public SomeProperty
    {
       get{return _inner.SomeProperty;
    }
}

If you insist on joined-subclass approach then I believe you'll need to implement some identifier to be unique in addition to the key NHibernate uses to subclass across tables.

MIKE[/code]

Already figured out this same solution, thank you anyway!