Designates a
ManyToOne
or
OneToOne
relationship attribute that provides the
mapping for an
EmbeddedId
primary key, an attribute within
an
EmbeddedId
primary key, or a simple primary key of
the parent entity. The
value
element specifies the
attribute within a composite key to which the relationship
attribute corresponds. If the entity's primary key is of the same
Java type as the primary key of the entity referenced by the
relationship, the value attribute is not specified.
Example:
// parent entity has simple primary key
@Entity
public class Employee {
@Id long empId;
String name;
...
}
// dependent entity uses EmbeddedId for composite key
@Embeddable
public class DependentId {
String name;
long empid; // corresponds to primary key type of Employee
}
@Entity
public class Dependent {
@EmbeddedId DependentId id;
...
@MapsId("empid") // maps the empid attribute of embedded id
@ManyToOne Employee emp;
}