I'm using the version 2.1.8 of Hibernate.

- I have a class A with a list of B's.
- B is an abstract class and some concrete classes B1, B2, B3,... extend it.
- B's are mapped using a table per class hierarchy.

The problem is that A doesn't know all B's implementations and in some situations I don't need to load all B's concrete classes(I don't use all mappings), but the data exists in the database so I get the exception cannot instantiate an abstract class or interface ...

Is there a way to avoid this error and only to load the instances he knows?

Thanks

You can either use

in the class mapping to filter out some discriminator values which should never be read by hibernate, or use dynamic filters, see chapter 18 of the reference manual.

HTH
Ernst

The problem is that sometimes I start with all mappings and sometimes with a subset of them.

So I don't know the other types to exclude them filtering the datas.

Thanks,

I'm using the strategy table per subclass

Hi Josep

Instead of filtering the ones you don't want (and don't know) you could of course ask for the ones you want (and hopefully know).

HTH
Ernst

Gues this is what you're realy looking for



See chapter 15.7 of the reference manual.

HTH
Ernst

Hi Ernst
I will try, but I need Hibernate 3 isn't it? So I have to migrate my mappings firts.

I have:
- A class CL1 wich has a list of CL2.
- CL2 is an abstract class in order to extend adding new behaviours not yet known.
- I have concrete CL2 classes CL2-1,CL2-2, ...
- Each class (CL2, CL2-1,...) maps to a table.
- Another user wil add CL2-x concrete classes and its new mappings.
- When the system starts will load all the mappings indicated.
- If I want to get the list of CL2 that an instance of CL1 has, I do it with a simple get method returning a List.
-The problem arises when in the database the table TCL2 has registers that are mapping CL2-2 instances and I'm not using these mappings.

In this situation, where you suggest to put this filter?

Thanks,

According to the docs in chapter 11.7. The where clause the special property class is available in H2 as well.

HTH
Ernst

Thanks Ernst,

I've been so busy with another thing.
I've migrate to hibernate 3 and I've solved it with the new inheritance mapping table per concrete class (union-class)