InheritanceType.JOINED and Implicit Polymorphism

patrick_ibg · **Joined:** Sat Sep 17, 2005 10:41 am **Posts:** 49

Let's say I have the following three entities:

Code:

@Entity (access = AccessType.FIELD)
@Inheritance (strategy = InheritanceType.JOINED)
public class Account
  implements java.io.Serializable
{
  @Basic
  private String userName ;
  @Basic
  private String password ;

   // etc...
}

@Entity (access = AccessType.FIELD)
public class Customer
  extends Account
  implements java.io.Serializable
{
  @ManyToOne
  private Address address

  // etc...
}

@Entity (access = AccessType.FIELD)
public class Admin
  extends Account
  implements java.io.Serializable
{
  @OneToMany
  private Set<Permission> permissions ;

  // etc..
}

I can create one type of account or another, simply by constructing the object and calling:

Code:

  session.saveOrUpdate (new Admin()) ;
  session.saveOrUpdate (new Customer ()) ;

Likewise I can query.

However, what if I have an already persisted Admin object, and I would like to make it also a Customer? How can I make it such that there is one entry in the Account table that corresponds to one entry each in the Admin and Customer tables?

Thanks...

emmanuel · **Posted:** Sat Dec 10, 2005 1:28 pm

how can you change the object class type from Customer to Admin in plain Java at runtime?
This is not possible, hence not in ORMs
You should consider not using inheritance for what you want.