JPA Multiple Embedded fields

Question

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.

Answer 1

The generic JPA way to do it is with @AttributeOverride. This should work in both EclipseLink and Hibernate.

@Entity  public class Person {   @AttributeOverrides({     @AttributeOverride(name="street",column=@Column(name="homeStreet")),     ...   })   @Embedded public Address home;    @AttributeOverrides({     @AttributeOverride(name="street",column=@Column(name="workStreet")),     ...   })   @Embedded public Address work;   }    @Embeddable public class Address {     @Basic public String street;     ...   } } 

Answer 2

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