JPA not saving foreign key to @OneToMany relation

Question

I'm using Spring with Hibernate as a JPA provider and are trying to get a @OneToMany (a contact having many phonenumbers) to save the foreign key in the phone numbers table. From my form i get a Contact object that have a list of Phone(numbers) in it. The Contact get persisted properly (Hibernate fetches an PK from the specified sequence). The list of Phone(numbers) also gets persisted with a correct PK, but there's no FK to the Contacts table.

public class Contact implements Serializable {      @OneToMany(mappedBy = "contactId", cascade = CascadeType.ALL, fetch=FetchType.EAGER)     private List<Phone> phoneList;  }  public class Phone implements Serializable {      @JoinColumn(name = "contact_id", referencedColumnName = "contact_id")     @ManyToOne     private Contact contactId;  }  @Repository("contactDao") @Transactional(readOnly = true) public class ContactDaoImpl implements ContactDao {      @Transactional(readOnly = false, propagation = Propagation.REQUIRES_NEW)     public void save(Contact c) {         em.persist(c);         em.flush();     } }   @Controller public class ContactController {     @RequestMapping(value = "/contact/new", method = RequestMethod.POST)     public ModelAndView newContact(Contact c) {         ModelAndView mv = new ModelAndView("contactForm");         contactDao.save(c);         mv.addObject("contact", c);         return mv;     } } 

Hopefully I got all of the relevant bits above, otherwise please let me know.

Answer 1

You have to manage the Java relationships yourself. For this kind of thing you need something like:

@Entity public class Contact {   @Id   private Long id;    @OneToMany(cascade = CascadeType.PERSIST, mappedBy = "contact")   private List<Phone> phoneNumbers;    public void addPhone(PhoneNumber phone) {      if (phone != null) {         if (phoneNumbers == null) {             phoneNumbers = new ArrayList<Phone>();                   }         phoneNumbers.add(phone);         phone.setContact(this);      }   }    ... }  @Entity public class Phone {   @Id   private Long id;    @ManyToOne   private Contact contact;    ... } 

Answer 2

In reply to Cletus' answer. I would say that it's important to have the @column annotation on the id fields, as well as all the sequence stuff. An alternative to using the mappedBy parameter of the @OneToMany annotation is to use the @JoinColumn annotation.

As a kinda aside your implementation of addPhone needs looking at. It should probably be something like.

public void addPhone(PhoneNumber phone) {     if (phone == null) {         return;     } else {         if (phoneNumbers == null) {             phoneNumbers = new ArrayList<Phone>();         }         phoneNumbers.add(phone);         phone.setContact(this);     } }