[CONF] OpenJPA: Embeddable samples (page edited)

Tue, 23 Jun 2009 08:59:33 -0700

Page Edited : openjpa : Embeddable samples

Embeddable samples has been edited by Rick Curtis (Jun 23, 2009).

(View changes)

Content:

Embeddable classes

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.

In short, an embeddable is ...

Examples

\< IMAGE \\\>

Collections of Embeddables

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

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

	public Address(){
	}
//...
}
User2.java
@Entity
public class User2 {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int id;

	@ElementCollection
	@CollectionTable(name="user_addresses")
	@OrderColumn
	private Set<Address> addresses = new HashSet<Address>();
	
	public User2(){
	}
//...
}

Relationships from Embeddables

In the code snippet below, there is an Address embeddable with a ManyToOne relationship to a Coordinates Entity.

Address.java
@Embeddable
public class Address {
	@Basic
	private String street;
	@Basic
	private String city;
	@Basic
	private String state;
	@Basic
	private Integer zip;
	
	@ManyToOne(cascade=CascadeType.ALL)
	Coordinates coordinates;

	public Address(){
	}
//...
}
Coordinates .java
@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;
	}
//...
}

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.

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

	public Address(){
	}
//...
}
Phone.java
@Embeddable
public class Phone {
	@Basic
	private String number;
//...
}
ContactInfo.java
@Embeddable
public class ContactInfo {
	public ContactInfo(){	
	}
	
	@Embedded
	Address homeAddress;
	
	@Embedded
	Phone homePhone;
//...
}
User.java
@Entity
public class User {
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int id;
	@Embedded
	ContactInfo contactInfo;
	
	public User(){
	}
//...
}

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