views:

2817

answers:

1

Is it possible for a JPA entity class to contain two embedded (@Embedded) fields? An example would be:

@Entity
public class Person {
    @Embedded
    public Address home;

    @Embedded
    public Address work;
}

public class Address {
    public String street;
    ...
}

In this case a Person can contain two Address instances - home and work. I'm using JPA with Hibernate's implementation. When I generate the schema using Hibernate Tools, it only embeds one Address. What I'd like is two embedded Address instances, each with its column names distinguished or pre-pended with some prefix (such as home and work). I know of @AttributeOverrides, but this requires that each attribute be individually overridden. This can get cumbersome if the embedded object (Address) gets big as each column needs to be individually overridden.

+4  A: 

If you want to have the same embeddable object type twice in the same entity, the column name defaulting will not work: at least one of the columns will have to be explicit. Hibernate goes beyond the EJB3 spec and allows you to enhance the defaulting mechanism through the NamingStrategy. DefaultComponentSafeNamingStrategy is a small improvement over the default EJB3NamingStrategy that allows embedded objects to be defaulted even if used twice in the same entity.

From Hibernate Annotations Doc: http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#d0e714

Loki