I am wondering if it is possible using annotations to persist the attributes
map in the following class using JPA2
public class Example {
long id;
// ....
Map<String, String> attributes = new HashMap<String, String>();
// ....
}
As we already have a pre existing production database, so ideally the values of attributes
could map to the following existing table:
create table example_attributes {
example_id bigint,
name varchar(100),
value varchar(100));
JPA 2.0 supports collections of primitives through the @ElementCollection
annotation that you can use in conjunction with the support of java.util.Map
collections.
Something like this should work:
@Entity
public class Example {
@Id long id;
// ....
@ElementCollection
@MapKeyColumn(name="name")
@Column(name="value")
@CollectionTable(name="example_attributes", joinColumns=@JoinColumn(name="example_id"))
Map<String, String> attributes = new HashMap<String, String>(); // maps from attribute name to value
}