JPA inheritance issue

henryedsl · **Joined:** Fri Aug 07, 2009 9:21 am **Posts:** 4

Hello!

First of all excuse me for my english, it's not very good.

I have a super class named say A with the @MappedSuperclass annotation, and i have a class named say B which extends A.

In class A i have defined a field named profession, which returns a Person, it's as follows:

Code:

@MappedSuperclass
public class A {

@JoinColumn(name="profession")
@ManyToOne(optional=false) 
private Person profession;

public Person getProfession() {
return profession;
}

} 

In class B, which extends A, i need to overwrite field profession so it returns a Doctor instead a Person, as follows:

Code:

public class B extends A {
@JoinColumn(name="profession")
@ManyToOne(optional=false) 
private Doctor profession;

public Doctor getProfession() {
return profession;
}

} 

As you can imagine, Doctor extends Person.

So far so good, the problem appears when i run my application, i get a message in my Tomcat logs saying:

Quote:

Caused by: org.hibernate.MappingException: Duplicate property mapping of profession found in org.admon.db.bienes.modelo.DesincorporacionInmuebles

It is like i can not overwrite a field defined in the super class, because it says i have a duplicate property.

Am i doing something wrong?

I hope i was clear, and again, sorry if my english is not that good.

Thanks in advance for your time.
Regards!

Cameron McKenzie · **Posted:** Tue Aug 11, 2009 8:18 am

Well, you really are mapping the same name twice in the subclass, right? So, there is a duplicate. If the property in the sublcass had a different name, you'd be fine.

henryedsl · **Joined:** Fri Aug 07, 2009 9:21 am **Posts:** 4

Hello Mr. Cameron, thanks for your answer.

Well, i changed the property name in the subclass and now there is no duplicate, but now i have another error:

Quote:

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: com.tests.class column: profession (should be mapped with insert="false" update="false")

I understand why i'm getting that error, but now i'm thinking that maybe i should not declare that field profession in the super class, is there something i can do to solve this? some advice about what i should do?

Thanks for your time, and thanks again Mr. Cameron.

henryedsl · **Joined:** Fri Aug 07, 2009 9:21 am **Posts:** 4

Hello again, i answer to myself.

I've changed my super class, i did not put the @JoinColumn(name="profession") to declare the property in the super class, as follows

i changed this:

Code:

@MappedSuperclass
public class A {

@JoinColumn(name="profession")
@ManyToOne(optional=false)
private Person profession;

public Person getProfession() {
return profession;
}

} 

for this:

Code:

@MappedSuperclass
public class A {

@ManyToOne(optional=false)
private Person profession;

public Person getProfession() {
return profession;
}

} 

Now i do not get a Repeated column in mapping for entity error.
I hope it's correct what i did, if not, i would thank you if you let me know.

Regards...

jwenting · **Joined:** Tue Jan 03, 2006 9:20 am **Posts:** 74

not sure what that would create at database level, you'd have to try.

An option I'd try would be to generify the thing and make the getPerson method return a generic type.

So you'd get something like

Code:

public abstract class A<T extends Person> {
    @ManyToOne
    protected Person profession;

   public abstract T getProfession();
}

////////

public class B extends A<Doctor> {
    @SuppressWarnings("unchecked")
    public Doctor getProfession() {
       return (Doctor) profession;
    }
}

I haven't tried this, don't know if it'd work, but it's what I'd try first.