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Difference between revisions of "EclipseLink/Examples/JPA/Dynamic/PropertiesTable"
< EclipseLink | Examples | JPA | Dynamic
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<source lang="java"> | <source lang="java"> | ||
| + | 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(); | ||
| − | |||
| − | |||
| − | |||
</source> | </source> | ||
Revision as of 13:04, 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:
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();