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An entity may use other fine-grained classes to represent entity state. Instances of these classes, unlike
entity instances, do not have persistent identity of their own. Instead, they exist only as part of the state
of the entity to which they belong. (From 2.0 Proposed Final Draft March 13, 2009 – do I need to provide footnote or something?)

In short, an embeddable is a seperation of data into a Java class that relies on the owning Entity for it's identity. Many(most) times an embeddable resides in the same database row as the owning Entity.

Review the getting started page on how to run the samples.

Samples

\< IMAGE \\\>

#Collections of Embeddables
#Relationships from Embeddables
#Nested Embeddables

Collections of Embeddables

In the code snippet below, there is a User2 User Entity which has a collection of ordered Embedded addressaddresses.

@Embeddable
public class Address {
	@Basic
	private String street;
	@Basic
	private String city;
	@Basic
	private String state;
	@Basic
	private Integer zip;

	public Address(){
	}
//...
}

@Entity
public class User2User {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int id;

	@ElementCollection
	@CollectionTable(name="user_addressesaddress")
	@OrderColumn
	private Set<Address> addresses = new HashSet<Address>();
	
	public User2User(){
	}
//...
}

...
// Select Entity based off a query over a collection of embeddables
Query q = em.createQuery("SELECT u FROM User u , in (u.addresses) a WHERE a.state='xx'");
// TODO -- add more!
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Relationships from Embeddables

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@Entity
public class Coordinates {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	int id;
	
	@Basic
	double longitude;
	@Basic
	double latitude;
	public Coordinates(){
	}
	public Coordinates(double lon, double lat){
		longitude=lon;
		latitude=lat;
	}
//...
}

...
// Embedded -> relationship traversal
Query q = em.createQuery("SELECT u FROM User u , in (u.addresses) a WHERE a.coordinates.longitude=xxx");
// TODO -- add more!
...

Nested Embeddables

In the code snippet below, there is a User Entity which has an embedded ContactInfo. ContactInfo contains two other embeddeded embeddables, Address and Phone.

...

@Embeddable
public class Phone {
	@Basic
	private String phone_number;
	@Basic
	private String phone_type;
//...
}

@Embeddable
public class ContactInfo {
	public ContactInfo(){	
	}
	
	@Embedded
	Address homeAddress;
	
	@Embedded
	Phone homePhone;
//...
}

@Entity
public class User {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int id;
	@Embedded
	ContactInfo contactInfo;
	
	public User(){
	}
//...
}

...
// Nested embeddables traversal
Query q = em.createQuery("SELECT u FROM User u WHERE u.contactInfo.homePhone.number='507-555-5555' AND u.contactInfo.homePhone.type='cell'");
// TODO -- add more!
...