Relationships and tracking changes

Hello !!

I am new in JPA / ObjectDB development and I have many questions:

3. Object relationship

I try to create a 1->n relation (EBVerlag is 1 and EBUser is n) between two tables:

Table "EBVerlag":

@Entity(name="VERLAG")
public class EBVerlag extends Pojo implements Serializable {

private static final long serialVersionUID = 1L;

@Id @Column(name = "ID") @GeneratedValue(strategy = GenerationType.AUTO)  private Long id;

@OneToMany (fetch=FetchType.LAZY,cascade=CascadeType.ALL, mappedBy="VERLAG_ID") private List<EBUser> users;

Table "EBUser":

@Entity(name="USER")
public class EBUser extends Pojo implements Serializable{

private static final long serialVersionUID = 1L;

@Id @Column(name = "ID") @GeneratedValue(strategy = GenerationType.AUTO) private Long id;

@ManyToOne @Column(name = "VERLAG_ID") @JoinColumn(name="VERLAG_ID", insertable=false, updatable=false) private EBVerlag verlag=null;

3.1. Please take a look at column names and tell me, if I did the connection between these two tables correctly or not.

3.2. Both POJO-s extend my own class "Pojo.class" which looks like this:

public class Pojo {
private transient boolean changed=false;
public boolean isChanged(){
  return changed;
}
public void setChanged(boolean changed){
  this.changed = changed;
}

...as you can see, I tried to manage changes inside of the tables by the hand. So let's say: if I call a set-method of my POJO and the new value is different than the old value, then I call setChanged(true). Is there a better way to manage such changes (maybe automatically?). Please consider that I cannot use Spring or similar, because the test-project works inside of GWT-context.

ObjectDB ignores ORM annotations such as @Column and JoinColumn.

Therefore, Java field names should be used in mappedBy. See also this manual page.