Collection mapping of Elements in JPA

[Joe San]

Guys,

This is regarding an example from the JPA book.

@Entity
public class Employee {
@Id private int id;
private String name;
private long salary;
// ...
@ElementCollection(targetClass=VacationEntry.class)
private Collection vacationBookings;
@ElementCollection
private Set<String> nickNames;
// ...
}

Where VacationEntry is marked with an Embedable annotation. My question is:

Is the Embedded annotation optional and that the ElementCollection is enough to make the Persistence Provider to be aware that vacationBookings is of Embedded type?

[Tamas Polgar]

Hi there,

From JPA spec (http://download.oracle.com/javaee/6/api/javax/persistence/Embedded.html)
"Specifies a persistent field or property of an entity whose value is an instance of an embeddable class. The embeddable class must be annotated as Embeddable. "

For me it means you should use it for single attributes, not collections. Howewer, the annotation api doesnt deny it, and with eclipselink, and hibernate it works for me.
but in the xml api, which is better-defined, its not allowed.

So I think you should not use it,
the generic type, or the targetClass attribute of @ElementCollection is enough.