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Embeddable samples |
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| minLevel | 2 |
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| indent | 20px |
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| style | disc |
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Collections Embeddables
Relationships Embeddables
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. (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
Schema | Class diagram |
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 Image Added
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#Collections of Embeddables
#Relationships from Embeddables
#Nested Embeddables
Collections of Embeddables
In the code snippet below, there is a User Entity which has a collection of Embedded addresses.
| Code Block |
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| title | Address.java |
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| borderStyle | solid |
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@Embeddable
public class Address {
@Basic
private String street;
@Basic
private String city;
@Basic
private String state;
@Basic
private Integer zip;
public Address(){
}
//...
}
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| Code Block |
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| title | User.java |
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| borderStyle | solid |
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@Entity
public class User {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
@ElementCollection
@CollectionTable(name="user_address")
private Set<Address> addresses = new HashSet<Address>();
public User(){
}
//...
}
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| Code Block |
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| title | JPQL.java |
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| borderStyle | solid |
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...
// 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
In the code snippet below, there is an Address embeddable with a ManyToOne relationship to a Coordinates Entity.
| Code Block |
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| title | Address.java |
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| borderStyle | solid |
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@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(){
}
//...
}
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| Code Block |
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| title | Coordinates .java |
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| borderStyle | solid |
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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;
}
//...
}
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| Code Block |
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| title | JPQL.java |
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| borderStyle | solid |
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...
// Embedded -> relationship traversal
Query q = em.createQuery("SELECT u FROM User u , in (u.addresses) a WHERE a.coordinates.longitude=xxx");
// TODO -- add more!
...
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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.
...
| Code Block |
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| title | Phone.java |
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| borderStyle | solid |
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@Embeddable
public class Phone {
@Basic
private String phone_number;
@Basic
private String phone_type;
//...
}
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| Code Block |
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| title | ContactInfo.java |
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| borderStyle | solid |
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@Embeddable
public class ContactInfo {
public ContactInfo(){
}
@Embedded
Address homeAddress;
@Embedded
Phone homePhone;
//...
}
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| Code Block |
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| title | User.java |
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| borderStyle | solid |
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@Entity
public class User {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int id;
@Embedded
ContactInfo contactInfo;
public User(){
}
//...
}
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| Code Block |
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| title | JPQL.java |
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| borderStyle | solid |
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...
// 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!
...
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