Entity field mapping

Question

Good day, everyone!
I have two modules: API and EJB.
Main idea is that api should not have any dependencies
and all entities impliments interfaces.
So I have Operator(from API) interface and OperatorEntity(from EJB).
Here is the code
OperatorEntity.java
@Entity(name = "Operator")
@Table(name = "tbs5_operator")
@NamedQueries(value = {@NamedQuery(name = "getOperators", query = "SELECT object(o) FROM Operator o"),
        @NamedQuery(name = "getOperatorById", query = "SELECT object(o) FROM Operator o WHERE o.id = :id")})
public class OperatorEntity implements Operator, Serializable {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private long id;
    @Column(name = "title")
    private String title;
     @Column(name = "npas_operator_code")
     private String npasOperatorCode;
    @OneToOne()
    @JoinTable(name = "tbs5_operator",
               joinColumns = { @JoinColumn(name = "parent_id")
                } , inverseJoinColumns = { @JoinColumn(name = "id")
     private Operator parent;
     private static final long serialVersionUID = 1L;
    public OperatorEntity() {
     public String getNpasOperatorCode() {
          return npasOperatorCode;
     public void setNpasOperatorCode(String npasOperatorCode) {
          this.npasOperatorCode = npasOperatorCode;
     public long getId() {
        return id;
    protected void setId(long id) {
        this.id = id;
    public String getTitle() {
        return title;
    public void setTitle(String title) {
        this.title = title;
    public Long getParentId() {
        return parentId;
     public Operator getParent() {
          return parent;
     public void setParent(Operator parent) {
          this.parent = parent;
     }Operator.java
public interface Operator extends ValueObject {
     String getTitle();
     void setTitle(String title);
     Long getParentId();
     void setParentId(Long parentId);
     boolean isVirtual();
     String getNpasOperatorCode();
     void setNpasOperatorCode(String npasOperatorCode);
     Operator getParent();
     void setParent(Operator parent);
}I get an error, which says that parent should be entity-typed...
Is there any way to mark field parent as entity, but not change
its type to OperatorEntity?
Thank you
Andrey

Answer 1

Ok. Everything was fixed.
i found all information that I needed here
http://www.oracle.com/technology/products/ias/toplink/jpa/resources/toplink-jpa-annotations.html#JoinColumn
here is how I fixed my problem:
I used entityTarger param in @OneToOne annotation to identify interface as entity:
targetEntity = OperatorEntity.class
Code:
@Entity(name = "Operator")
@Table(name = "tbs5_operator")
@NamedQueries(value = {@NamedQuery(name = "getOperators", query = "SELECT object(o) FROM Operator o"),
@NamedQuery(name = "getOperatorById", query = "SELECT object(o) FROM Operator o WHERE o.id = :id")})
public class OperatorEntity implements Operator, Serializable {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     @Column(name = "id")
     private long id;
     @Column(name = "title")
     private String title;
     @Column(name = "npas_operator_code")
     private String npasOperatorCode;
     @OneToOne(targetEntity = OperatorEntity.class)
     @JoinTable(name = "tbs5_operator",
               joinColumns = {@JoinColumn(
                         name = "parent_id",
                         referencedColumnName = "id"
     private Operator parent;
     @OneToOne(targetEntity = CountryEntity.class)
     @JoinTable(
               name = "tbs5_country",
               joinColumns = {@JoinColumn(
                         referencedColumnName = "country_id",
                         name = "id"
     private Country country;
     private static final long serialVersionUID = 1L;
     public OperatorEntity() {
     public String getNpasOperatorCode() {
          return npasOperatorCode;
     public void setNpasOperatorCode(String npasOperatorCode) {
          this.npasOperatorCode = npasOperatorCode;
     public long getId() {
          return id;
     protected void setId(long id) {
          this.id = id;
     public String getTitle() {
          return title;
     public void setTitle(String title) {
          this.title = title;
     public boolean isVirtual() {
          return parent != null;
     public Operator getParent() {
          return parent;
     public void setParent(Operator parent) {
          this.parent = parent;
     public Country getCountry() {
          return country;
     public void setCountry(Country country) {
          this.country = country;
     public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
          OperatorEntity that = (OperatorEntity) o;
          if (id != that.id) return false;
          if (npasOperatorCode != null ? !npasOperatorCode.equals(that.npasOperatorCode) : that.npasOperatorCode != null)
               return false;
          if (parent != null ? !parent.equals(that.parent) : that.parent != null) return false;
          if (title != null ? !title.equals(that.title) : that.title != null) return false;
          return true;
     public int hashCode() {
          int result;
          result = (int) (id ^ (id >>> 32));
          result = 31 * result + (title != null ? title.hashCode() : 0);
          result = 31 * result + (npasOperatorCode != null ? npasOperatorCode.hashCode() : 0);
          result = 31 * result + (parent != null ? parent.hashCode() : 0);
          return result;
}Hope this will help others.
Regards, Andrey