Id in superclass

dharma · **Posted:** Mon Oct 09, 2006 6:53 am

Hibernate version:3.2

The case is pretty trivial but i cant solve it with annotations.

I have a base class that handles the id :

Code:

public abstract BaseEntity
{
   private Long id;

   public Long getId() { return id;}
...
}

A subclass ClassA defined like this :

Code:

public ClassA extends BaseEntity
{
   private String name1;

   public String getName1() { return name1;}
...
}

and a subclass ClassB :

Code:

public ClassB extends BaseEntity
{
   private String name2;

   public String getName2() { return name2;}
...
}

Each subclass has a different strategy to generate id : "sequence" for ClassA and "assigned" for classB

I tried many examples, but it failed, how could I add annotations to model that ?
Any help appreciated!

emmanuel · **Posted:** Mon Oct 09, 2006 5:30 pm

you can't

dharma · **Posted:** Tue Oct 10, 2006 11:12 am

Emmanuel, I've found a working solution.
Here it is :

Code:

@MappedSuperclass
@AccessType("field")
public abstract class BaseEntity
{
   @Id 
   @GeneratedValue(generator="ID_STORE")
   private Long id;

       public Long getId() { return this.id;}
...
}


@Entity
@javax.persistence.SequenceGenerator(
    name="ID_STORE",
    sequenceName="classA_id_seq",
    allocationSize=1
)
@AccessType("field")
public ClassA extends BaseEntity
{
   private String name1;

   public String getName1() { return name1;}
...
}

@Entity
@GenericGenerator(name = "ID_STORE", strategy = "assigned")   
@AccessType("field")
public ClassB extends BaseEntity
{
   private String name2;

   public String getName2() { return name2;}
...
}

Hope it can help.
Richard

emmanuel · **Posted:** Tue Oct 10, 2006 11:29 am

Funny, I didn't write the code to purposely allow that. Nice to see this working

dharma · **Posted:** Tue Oct 10, 2006 12:08 pm

Actually the result is very nice, because it is basically flexible.
Glad to hear the author didn't expect that ! ;-)
Richard

ari1974 · **Joined:** Tue Jun 14, 2005 3:21 pm **Posts:** 9

Are there plans to allow for the sequence generator to be moved to the mapped superclass? Currently, that fails -- the sequence generator has to be in the entity, even if you are declaring the id field in the MappedSuperclass, like above.
I am aware that you can declare the sequence once in an xml file, but we are trying to avoid xml declarations wherever possible for the sake of a consistent approach.
Allowing for declaring a SequenceGenerator, or @TypeDef, or other declaration, in a MappedSuperclass, would avoid duplicate declarations.

emmanuel · **Posted:** Tue Oct 17, 2006 4:55 pm

open a JIRA issue, even better with a test case.
Thanks

aditkris · **Posted:** Fri Jan 04, 2008 5:32 pm

I have a problem similar to the mentioned above. I have a mapped superclass that has an ID attribute. I have two child classes to the parent.

In my subclass I want to map it to an ID column and want to use a sequence (SEQUENCE1) to generate the ID values.

In another class I want to use another sequence (SEQUENCE2) to generate the ID values.

I tried to do this as explained above but it is using only Sequence and the one mentioned in the BaseClass.

My problem is I want to use two different sequences for different entities.

Is it possible to have two different sequences???