I have been using Hibernate 2.1.2 and MSSQLServer using Type 4 JDBC driver along with Spring and Weblogic.

I have been able to use table-per-class-hierarchy mapping strategy to persist and retrieve data.

Now I have run into a situation wherein I have to know the discriminator value given the primary key. Based on that, I will have to retrieve the corresponding subclass instance.

For eg. using the example in Ch.16,

I want to retrieve the payment type given the "id".

I tried the following HQL query.
"from Payment as payment where payment.id=:id"

With this method.
public String getPaymentType(int id) throws SomeException{
....................
}

A "null" is returned no matter what. I can retrieve other columns without any problem.

Is there a workaround?
Thanks
Madhu

Do you have the discriminator mapped as a property on the base class?

In the base class, its not declared as a property.

But as a discriminator, yes.

<discriminator
column="PAYMENT_TYPE"
type="java.lang.String"
/>

Madhu

Good Morning

I have tried using named hql queries, named sql queries, plain sql queries in conjunction with Hibernate to resolve this problem. My problem still remains unsolved.

Can anyone please tell me if this is possible or not? Hasnt anyone else been in this situatino before? Thats kind of hard to believe.

If I know that its not possible using Hibernate, I can look into alternate options for this single case.

Thanks
Madhu

Got the fix hiding deep inside an earlier post. Maybe I didnt dig deep enough.
(;-)


In addition to declaring the discriminator as mentioned above,

map the same <property> with insert="false" update="false".

That way, the base class can access the value. It also prohibits the cbase class from changing the discriminator value.

Hopefully others will find this helpful.

Thanks
Madhu