How to map ManyToOne relationship with Composite key?

[Ricardo Preston]

Hi all. I'm having great difficulty trying to map a ManyToOne relationship between 2 classes, when one class has a composite primary key. I'm running JBoss 5.0 and Seam.

I have a Form class that has many Rules. If at first I ignore the composite key and just use 1 field as the key, all is fine (though of course I get multiple matches instead of one). The code looks something like this:

// Form Class
@Entity
@Table(name = "MY_FORM_TABLE")
// @IdClass(FormKey.class)
public class Form implements Serializable {

	// @EmbeddedId FormKey key;
	private String name; // FORM_NAME
	private int version; // FORM_VERSION
	private List<Rule> rules = new ArrayList<Rule>();

	...

	@OneToMany(cascade=CascadeType.ALL, mappedBy="form")
	public List<Rule> getRules() {
		return rules;
	}
}

// ----------------------------------------
// Class Rule

@Entity
@Table(name = "MY_RULE_TABLE")
public class Rule extends BaseRule implements Serializable
{
	private String formName; // FORM_NAME
	private Integer formVersion; // FORM_VERSION
	private Form form;

	...

	@ManyToOne
	@JoinColumns({
		@JoinColumn(name="FORM_NAME", referencedColumnName="FORM_NAME", nullable = false, insertable = false, updatable = false) /* ,
                 @JoinColumn(name="FORM_VERSION", referencedColumnName="FORM_VERSION", nullable = false, insertable = false, updatable = false) */
	})
	public Form getForm() {
		return form;
	}   
}

Now if I uncomment the 2nd @JoinColumn annotation, I get the error:

org.hibernate.AnnotationException: A Foreign key refering xxx.yyy.Form from xxx.yyy.Rule has the wrong number of column. should be 1

If I create a PK class FormKey.java to hold the form name & version, I then don't know how to construct the annotations in Rule, since I'm no longer joining columns directly, but mapping to a class Form.key instead.

Any ideas? Thanks.

[Mark Spritzler]

Don't you also have to uncomment out the IdClass annotations, etc. in the parent class?

Mark

[Ricardo Preston]

Yes, I do if I'm using the FormKey class, as well as uncommenting the @EmbeddedId line.