[news.eclipse.rt.eclipselink] Problem with Foreign Composite Key sharing

[philip.busby@xxxxxxx (Philihp Busby)]

My database has two entities; Company and Person. A Company can have many 
People, but a Person must have only one Company. The table structure looks 
as follows.

COMPANY
----------
owner   PK
comp_id PK
c_name

PERSON
----------------
owner    PK, FK1
personid PK
comp_id  FK1
p_fname
p_sname

It has occurred to me that I could remove PERSON.OWNER and derive it 
through the foreign key; however, I can't make this change without 
affecting legacy code.

I have modeled these as JPA-annotated classes;

@Entity
@Table(name = "PERSON")
@IdClass(PersonPK.class)
public class Person
   implements Serializable {

 @Id
 private String owner;

 @Id
 private String personid;

 @ManyToOne
 @JoinColumns(
   {@JoinColumn(name = "owner", referencedColumnName = "OWNER",
                insertable = false, updatable = false),
    @JoinColumn(name = "comp_id", referencedColumnName = "COMP_ID",
                insertable = true, updatable = true)})
 private Company company;

 private String p_fname;

 private String p_sname;

 ...and standard getters/setters...
}

@Entity
@Table(name = "COMPANY")
@IdClass(CompanyPK.class)
public class Company
   implements Serializable {

 @Id
 private String owner;

 @Id
 private String comp_id;

 private String c_name;

 @OneToMany(mappedBy = "company", cascade=CascadeType.ALL)
 private List people;

 ...and standard getters/setters...
}

My PersonPK and CompanyPK classes are nothing special, they just serve as 
a struct holding owner and the ID field, and override hashCode and 
equals(o).

So far so good. I come across a problem, however, when trying to deal with 
associations. It seems if I have an existing Company, and create a Person, 
and associate to the Person to the Company and persist the company, the 
association is not saved when the Person is inserted. For example, my main 
code looks like this:

EntityManager em = emf.createEntityManager();
em.getTransaction().begin();

CompanyPK companyPK = new CompanyPK();
companyPK.owner="USA";
companyPK.comp_id="1102F3";
Company company = em.find(Company.class, companyPK);

Person person = new Person();
person.setOwner("USA");
person.setPersonid("5116628123"); //some number that doesn't exist yet
person.setP_fname("Hannah");
person.setP_sname("Montana");
person.setCompany(company);
em.persist(person);

This completes without error; however in the database I find that the 
Person record was inserted with a null in the COMP_ID field. With 
EclipseLink debug logging set to FINE, the SQL query is shown as:

INSERT INTO PERSON (PERSONID,OWNER,P_SNAME,P_FNAME) VALUES (?,?,?,?)
 bind => [5116628123,USA,Montana,Hannah,]

I would have expected this to be saved, and the query to be equivalent to

INSERT INTO PERSON (PERSONID,OWNER,COMP_ID,P_SNAME,P_FNAME) VALUES 
(?,?,?,?,?)
 bind => [5116628123,USA,1102F3,Montana,Hannah,]

What gives? Is it incorrect to say updatable/insertable=true for one half 
of a composite key and =false for the other half? If I have 
updatable/insertable=true for both parts of the foreign key, then 
Eclipselink fails to startup saying that I can not use the column twice 
without having one set to readonly by specifying these options.