OneToOne foreign keys

rizwansaeed · **Joined:** Sat Jun 16, 2007 2:12 pm **Posts:** 2

Hi, I'm new to Hibernate and having problems getting a foreign key mapping working.

I have the following simple table structure which maps users to preferences:

Code:

CREATE TABLE Users
(
   userId    int   IDENTITY NOT NULL,
   userName varchar(50) NOT NULL 
)

CREATE TABLE UserPreferences
(
   prefId   int   IDENTITY NOT NULL ,
   userId   int   NOT NULL ,
   preferenceString   text NOT NULL 
)

My class implementations are as below (based on the Hibernate Owner/OwnerAddress example):

Code:

@Entity
@Table (name="Users")
public class User 
{
   @Id
   @GeneratedValue (strategy=GenerationType.IDENTITY)
   @Column (name="userId")
   private Integer   userId;
   
   @Column (name="userName")
   private String   userName;
   
   @OneToOne (cascade=CascadeType.ALL)
   @JoinColumn (name="userId")
   private Preferences   preferences;
   
   //   get/set methods...
}

@Entity
@Table (name="UserPreferences")
public class Preferences
{
   @Id
   @GeneratedValue (strategy=GenerationType.IDENTITY)
   @Column (name="prefId")
   private Integer   prefId;
   
   @GeneratedValue(generator = "fk")
      @GenericGenerator (strategy = "foreign", name = "fk", 
         parameters = @Parameter(name="property", value="user"))
   @Column (name="userId")
   private Integer   userId;
   
   @OneToOne (mappedBy="preferences", optional=false)
   private User user;
   
   @Column (name="preferenceString")
   private String preferenceString;
   
   //   get/set methods...
}

and finally my test case is as follows:

Code:

@Test
public void testSaveUserAndPreference() throws Exception
{
   Session   session = HibernateUtil.getSessionFactory().openSession();
   Transaction   tx = session.beginTransaction();

   User      user = new User();
   Preferences   prefs = new Preferences();

   prefs.setPreferenceString("test preferences");
   prefs.setUser(user);
   user.setPreferences(prefs);
   user.setUserName("test user with prefs");

   session.persist(user);
   tx.commit();
   session.close();

   HibernateUtil.shutdown();      
}

The problem I am having is that the userId is not being set on the UserPreference and hence gives me an insert exception:

Code:

Hibernate: 
    /* insert core.User
        */ insert 
        into
            Users
            (userName) 
        values
            (?)
Hibernate: 
    /* insert core.Preferences
        */ insert 
        into
            UserPreferences
            (preferenceString, userId) 
        values
            (?, ?)
12:08:22,265  WARN JDBCExceptionReporter:77 - SQL Error: 515, SQLState: 23000
12:08:22,265 ERROR JDBCExceptionReporter:78 - Cannot insert the value NULL into column 'userId', table 'dbo.UserPreferences'; column does not allow nulls. INSERT fails.

Any ideas what I am doing wrong?

emmanuel · **Posted:** Mon Jun 18, 2007 11:01 am

Have a look at the "foreign" generator

rizwansaeed · **Joined:** Sat Jun 16, 2007 2:12 pm **Posts:** 2

thanks for the reply. i thought i had done this with this:

Code:

   @GeneratedValue(generator = "fk") 
      @GenericGenerator (strategy = "foreign", name = "fk", 
         parameters = @Parameter(name="property", value="user")) 
   @Column (name="userId") 
   private Integer   userId; 
    
   @OneToOne (mappedBy="preferences", optional=false) 
   private User user; 

am i doing something wrong?

emmanuel · **Posted:** Mon Jun 18, 2007 6:46 pm

you need to put the generators on the
private Integer userId;
property along with @Id

rbattu · **Joined:** Tue Sep 25, 2007 11:37 am **Posts:** 2

@Id
@GeneratedValue(generator = "fk")
@GenericGenerator (strategy = "foreign", name = "fk",
parameters = @Parameter(name="property", value="user"))
@Column (name="userId")
private Integer userId;

@OneToOne (mappedBy="preferences", optional=false)
private User user;

For some reason it does not seem to work. I thought this is what Emmanuel suggested

- Ravinder.