Is there something like @IdOverride?

indi · **Joined:** Wed Jul 06, 2005 5:08 am **Posts:** 2

Is there an annotation that allows subclasses to override the id mapping of the base class? For example you have an abstract base class:

Code:

@EmbeddableSuperclass
public abstract class BaseEntity {
    private int id;

    @Id(generate = GeneratorType.NONE)
    public int getId() {
    }

    // Some logic using the id field.
}

And 2 concrete subclasses:

Code:

@Entity
public class NoAutonumbering extends BaseEntity {
}

@Entity
public class Autonumbering extends BaseEntity {
}

Most of the classes need to be mapped without sequences but some of them do use sequences in the database. I need a way to override the id mapping of the concrete Autonumbering class. I want it to be mapped using @Id(generate = GeneratorType.AUTO). I tried using the @AttributeOverride annotation but this does not seem to help me for @Id annotations.

emmanuel · **Posted:** Wed Jul 06, 2005 3:26 pm

No this is too evil IMO

indi · **Joined:** Wed Jul 06, 2005 5:08 am **Posts:** 2

Ah too bad, but I don't get why this would be evil? All these classes already exist and use an int as their identifier. The only difference lies in the database where some ids are auto generated and some are not.

I just wanted to be sure that mapping this existing object model to the database is not possible using annotations while it is using plain xml files.

emmanuel · **Posted:** Wed Jul 06, 2005 4:54 pm

It is possible, just to map your superclass

bunglebungle · **Joined:** Fri Mar 25, 2005 1:16 pm **Posts:** 13

I also think this would be useful. Could you explain what you mean by it is possible? Do you mean via xml, or is there some annotations workaround?

emmanuel · **Posted:** Fri Jul 29, 2005 12:41 am

bunglebungle wrote:

Could you explain what you mean by it is possible? Do you mean via xml, or is there some annotations workaround?

You know what, I've no fucking idea, I was on crack I guess ;-)

bunglebungle · **Joined:** Fri Mar 25, 2005 1:16 pm **Posts:** 13

Can you explain a little more why this is evil? I can see not bothering to support it if the EJB spec doesn't call for it, but all other attributes can be overridden. It seems to me that just because I declare some class has an identifier doesn't mean I really care how it is stored or where it comes from. I don't mean to keep picking at this, it's just that this is currently causing me some irritation because I have some old XDoclet mappings that do exactly what was asked about and I can't convert them to annotations. Would it be easy to change this behavior if I wanted to patch it myself?

emmanuel · **Posted:** Tue Aug 02, 2005 2:38 pm

What you can override so far are the column definitions.
I have a real bad feeling about the ability to override other parts. Mainly because the next step is to actually change the id property in the subclass that I don't want at all.

If you provide a patch I'll play with it and think it hard.

sdecleire · **Joined:** Fri Mar 31, 2006 7:16 am **Posts:** 2

bunglebungle wrote:

I also think this would be useful. Could you explain what you mean by it is possible? Do you mean via xml, or is there some annotations workaround?

I had the same need recently and achieved it by making my id @Transient in my abstract parent class and @Override it in my subclasses where i annotated it with @Id and @GeneratedValue.