Question

Assume that there is a Model bean with a unique contraint combining two columns (as composite primary keys) like this:

@Entity
@Table(uniqueConstraints = {  @UniqueConstraint(columnNames = { "key1", "key2" }) })
public class Rating extends Model {

    @ManyToOne
    @JoinColumn(name="key1", nullable=false)
    public Post key1;

    @ManyToOne
    @JoinColumn(name="key2", nullable=false)
    public User key2;
    ...
}

How can i find a finder for the method with the following signature:

public static Rating get(Post key1, User key2) { ... }

Answer 1

AFAIK, you’re not defining a composite key, but just an unique constraint between two properties. To define a composite key, you have to use the @EmbeddedId[1] or @IdClass[2] annotations.

I’ll go with @EmbeddedId, you can see an example of use here: http://weblogs.java.net/blog/bleonard/archive/2006/11/using_composite.html