Hello all,
currently I am making my first steps regarding JPA / Hibernate. The basics are pretty clear to me, but now I encountered a design problem I could not solve.
The problem is about the table design and/or the proper JPA/Hibernate annotations. I hope you can help me. :)
This is the class diagram of the entities I want to persist:
![]()
I want to keep track of the Flights of the two completely different classes: Duck (which is an Animal) and Plane, which both implement the interface Flyable.
A Flight has a reference to a single Flyable object. A Flyable has references to a set of Flights.
So I thought of the following tables:
![]()
My problem is, how do I reference a Flyable entity? I cannot use a base table "flyable" for Ducks and Planes, because Duck already has a parent table: "animal".
My classes with the JPA annotations so far look like this:
EDIT: added the missing method (see this post: http://www.java-forums.org/hibernate...tml#post349880)
What is the correct annotation for the "flyable" attribute of the Flight class? Or is there another solution to persist my classes?
I would really appreciate any help you can offer me!
Regards,
NegroManus
currently I am making my first steps regarding JPA / Hibernate. The basics are pretty clear to me, but now I encountered a design problem I could not solve.
The problem is about the table design and/or the proper JPA/Hibernate annotations. I hope you can help me. :)
This is the class diagram of the entities I want to persist:
I want to keep track of the Flights of the two completely different classes: Duck (which is an Animal) and Plane, which both implement the interface Flyable.
A Flight has a reference to a single Flyable object. A Flyable has references to a set of Flights.
So I thought of the following tables:
My problem is, how do I reference a Flyable entity? I cannot use a base table "flyable" for Ducks and Planes, because Duck already has a parent table: "animal".
My classes with the JPA annotations so far look like this:
Code:
@Entity
@Table(name = "flight")
public class Flight
{
@Id
@GeneratedValue
@Column(name = "id")
private long id;
// ???
private Flyable flyable;
}Code:
public interface Flyable
{
public Set<Flight> getFlights();
}Code:
@Entity
@Table(name = "animal")
@Inheritance(strategy = InheritanceType.JOINED)
public abstract class Animal
{
@Id
@GeneratedValue
@Column(name = "id")
private long id;
}Code:
@Entity
@Table(name = "duck")
public class Duck extends Animal implements Flyable
{
}Code:
@Entity
@Table(name = "plane")
public class Plane implements Flyable
{
@Id
@GeneratedValue
@Column(name = "id")
private long id;
}I would really appreciate any help you can offer me!
Regards,
NegroManus