Mapping Base class

MobyDick · **Joined:** Tue May 13, 2008 5:00 am **Posts:** 2

I wrote code:

Code:

class BaseClass
{
// some properties
}

and mapping for BaseClass

when

Code:

class Impl1 : BaseClass 
{
// some implementation
}

Code:

class Impl2 : BaseClass 
{
// some implementation
}

And save it:

Code:

BaseClass bc = new Impl1(...);
session.Save(bc);

And catch exception "Unknown entity class: Impl1".
Why is this happening?

wolli · **Posted:** Tue May 13, 2008 5:22 am

Since you save an Impl1 instance, you also need a mapping for that type. Even if you only want to store the BaseClass part of Impl1.

MobyDick · **Joined:** Tue May 13, 2008 5:00 am **Posts:** 2

wolli wrote:

Since you save an Impl1 instance, you also need a mapping for that type. Even if you only want to store the BaseClass part of Impl1.

I want to store only BaseClass, Impl1 this is only the implementation.
I tried also:

Code:

session.Save((BaseClass)bc);

It did not work.

wolli · **Posted:** Tue May 13, 2008 7:04 am

As I said, you need mappings for your implementation types. They can be empty, but you need them. Otherwise hibernate has no way to find out, what object it has to instantiate if a "BaseClass" is loaded, Impl1 or Impl2 !

If you want to separate the data from the logic/implementation, you can map the data as a component in both implementing classes.