Compound primary keys and OneToOne mapping - need advice

dovlex · **Joined:** Sun Apr 25, 2010 10:23 am **Posts:** 6

Hi,

I have three entities A, B, and C.

Code:

@Entity
public class A implements java.io.Serializable {

    @Id
    private String s;
    ...
}

@IdClass(BKey.class)
@Entity
public class B implements java.io.Serializable {

    @Id    
    @Temporal(javax.persistence.TemporalType.DATE)
    private Date pDate;
    
    @Id    
    @ManyToOne
    private A a;

    @Id
    protected int cInt;
    ...
}

@IdClass(CKey.class)
@Entity
public class C implements java.io.Serializable {

    @Id    
    @Temporal(javax.persistence.TemporalType.DATE)
    private Date pDate;
    
    @Id    
    @ManyToOne
    private A a;
    ...
}

I want to introduce OneToOne unidirectional read-only relationship with source being B and target being C. How would I do that?

I tried declaring C field in B as follows:

Code:

@OneToOne
@JoinColumns({
     @JoinColumn(name="A_S",referencedColumnName="A_S",insertable=false,updatable=false),
     @JoinColumn(name="PDATE",referencedColumnName="PDATE",insertable=false,updatable=false)})
protected C c;

However, every query to load B leaves field C as null. What am I doing wrong?

Thank you!

emmanuel · **Posted:** Mon Apr 26, 2010 7:56 am

Looks like it could work in theory. Which version of Hibernate are you playing with?
And what are your true mappings? From what you describe, there is a mismatch between your column names and your mapping.

dovlex · **Joined:** Sun Apr 25, 2010 10:23 am **Posts:** 6

Thanks Emmanuel. It was just a simple mistype of column name. Works perfectly.