[eclipselink-users] multiple access to same db field

[Yannick Majoros <yannick.majoros@xxxxxxxxxxxx>]

Hi,

 For historical reasons, some db fields in our model can be accessed 
from multiple fields in an entity class. Some example:

@Entity
public class StudentExam implements Serializable {
[...]
    @Column(name = "student_id", insertable = false, updatable = false)
    private Long studentId;
    @JoinColumns({@JoinColumn(name = "student_id", referencedColumnName 
= "id")})
    @ManyToOne
    private Student student;
[...]
}

My opinion is that following code is broken (will insert ok in db, but 
cache could be corrupted):

StudentExam studentExam = new StudentExam();
studentExam.setExam(someExam);
studentExam.setStudent(someStudent);
StudentExam savedStudentExam = entityManager.merge(studentExam);

Instead, I think we should use add this line before the merge:

studentExam.setStudentId(someStudent.getId());

... even if it sounds strange. Otherwise, studentExam.getStudentId() 
could be inconsistent, later. Our team cannot agree on this, we need to 
be sure. There is too much historical code, so simply removing studentId 
from the mapping is not an option :-(

 Could someone help me with an opinion, or even some specification 
reference?

 Thank you,

 Yannick Majoros

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