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Difference between revisions of "EclipseLink/Examples/JPA/Dynamic/PropertiesTable"
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* [[Using_EclipseLink_JPA_Extensions_%28ELUG%29#How_to_Use_the_.40BasicMap_Annotation | @BasicMap annotation documentation]] | * [[Using_EclipseLink_JPA_Extensions_%28ELUG%29#How_to_Use_the_.40BasicMap_Annotation | @BasicMap annotation documentation]] | ||
Revision as of 13:03, 23 July 2008
This example illustrates how EclipseLink JPA can enable dynamic or extensible models through the usage of a properties table. the properties table allows the developer to store additional information about an entity in a separate table using key-value pairs and have them reflected in the entity as a Map.
Background
this example makes use of a DirectMapMapping configured using the @BasicMap annotation.
Using @BasicMap
Here is a Person class which enables users to store arbitrary
@Entity public class Person { @Id private int id; @Column(name = "FNAME") private String firstName; @Column(name = "LNAME") private String lasttName; @BasicMap(keyColumn = @Column(name = "PNAME"), valueColumn = @Column(name = "PVALUE")) @CollectionTable(name = "PERSON_PROPERTY", primaryKeyJoinColumns = { @PrimaryKeyJoinColumn(name = "ID") }) private Map<String, String> properties; private Person() { this.properties = new HashMap<String, String>(); }
Example usage of mapping:
public static void main(String[] args) { EntityManagerFactory emf = Persistence .createEntityManagerFactory("example"); EntityManager em = emf.createEntityManager(); em.getTransaction().begin(); Person p1 = new Person(1, "Doug", "Clarke"); p1.setProperty("Work #", "6135551212"); p1.setProperty("Anniversary", "May 19, 2001"); p1.setProperty("Wife's Name", "Karla"); em.persist(p1); em.getTransaction().commit(); em.close(); emf.close(); }