How to write JPQL SELECT with embedded id?

Question

I\'m using Toplink essentials (JPA) + GlassFish v3 + NetBean 6.9

I have one table with composite primary key:

table (machine)
----------------
|PK ma         


        

Answer 1

Tested with Hibernate 4.1 and JPA 2.0

Make the following changes in order to work:

Class Machine.java

public class Machine {
   @EmbeddedId
   protected MachinePK machinePK;

   //getter & setters...
}

Class MachinePK.java

@Embeddable
public class MachinePK {
    @Column(name = "machineId")
    private String machineId;

    @Column(name = "workId")
    private String workId;

    //getter & setters...
}

...and for the JPQL query pass all column names:

Query query = em.createQuery("SELECT c.machinePK.machineId, c.machinePK.workId, "
                + "FROM Machine c WHERE c.machinePK.machineId=?");
query.setParameter(1, "10");

Collection results = query.getResultList();

Object[] obj = null;
List objPKList = new ArrayList();
MachinePK objPK = null;
Iterator it = results.iterator();
while(it.hasNext()){
    obj = (Object[]) it.next();
    objPK = new MachinePK();
    objPK.setMachineId((String)obj[0]);
    objPK.setWorkId((String)obj[1]);
    objPKList.add(objPK);
    System.out.println(objPK.getMachineId());
}