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Difference between revisions of "EclipseLink/Examples/JPA/Dynamic/PropertiesTable"
< EclipseLink | Examples | JPA | Dynamic
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* [[Introduction_to_Relational_Mappings_(ELUG)#Direct_Map_Mapping | DirectMapMapping documentation]] | * [[Introduction_to_Relational_Mappings_(ELUG)#Direct_Map_Mapping | DirectMapMapping documentation]] | ||
| − | == | + | == Example == |
Here is a Person class which enables users to store arbitrary | Here is a Person class which enables users to store arbitrary | ||
| + | === Mapping=== | ||
<source lang="java"> | <source lang="java"> | ||
@Entity | @Entity | ||
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</source> | </source> | ||
| − | + | === Using the Mapping === | |
<source lang="java"> | <source lang="java"> | ||
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</source> | </source> | ||
| + | |||
| + | |||
| + | === Querying the Map === | ||
| + | |||
| + | At present you can only query the mapping using EclipseLink's classic API in conjunction with JPA. this example queries the value in the map. | ||
| + | |||
| + | <source lang="java"> | ||
| + | ReadAllQuery raq = new ReadAllQuery(Person.class); | ||
| + | raq.setSelectionCriteria(raq.getExpressionBuilder().anyOf("properties").like("May%")); | ||
| + | List<Person> persons = JpaHelper.createQuery(raq, em).getResultList(); | ||
| + | </source> | ||
| + | |||
| + | |||
| + | In JPA 2.0 additional mapping types and JPQL grammar constructs will be added to query the keys or values | ||
Latest revision as of 13:43, 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.
Example
Here is a Person class which enables users to store arbitrary
Mapping
@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>(); }
Using the 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();
Querying the Map
At present you can only query the mapping using EclipseLink's classic API in conjunction with JPA. this example queries the value in the map.
ReadAllQuery raq = new ReadAllQuery(Person.class); raq.setSelectionCriteria(raq.getExpressionBuilder().anyOf("properties").like("May%")); List<Person> persons = JpaHelper.createQuery(raq, em).getResultList();
In JPA 2.0 additional mapping types and JPQL grammar constructs will be added to query the keys or values