org.eclipse.persistence.jpa
Class JpaHelper

java.lang.Object
  org.eclipse.persistence.jpa.JpaHelper

public class JpaHelper
extends java.lang.Object

This sample illustrates the JPA helper methods that may be of use to EclipseLink customers attempting to leverage EclipseLink specific functionality.

Author:

dclarke, gpelletie

Constructor Summary

JpaHelper()

Method Summary

static EntityManagerFactory	createEntityManagerFactory(Server session) Create a EclipseLink EMF given a ServerSession that has already been created and logged in.
static org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl	createEntityManagerFactory(java.lang.String sessionName) Create a EclipseLink EMF using a session name and sessions.xml.
static Query	createQuery(DatabaseQuery query, EntityManager em) Create a EclipseLink JPA query dynamically given a EclipseLink query.
static DatabaseQuery	getDatabaseQuery(Query query) Access the internal EclipseLink query wrapped within the JPA query.
static JpaEntityManager	getEntityManager(EntityManager entityManager) Convert a JPA entityManager into a EclipseLink specific one.
static org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl	getEntityManagerFactory(EntityManagerFactory emf) Given a JPA EntityManagerFactory attempt to cast it to a EclipseLink EMF.
static ReadAllQuery	getReadAllQuery(Query query) Access the internal EclipseLink query wrapped within the JPA query.
static ReportQuery	getReportQuery(Query query) Access the internal EclipseLink query wrapped within the JPA query.
static Server	getServerSession(EntityManagerFactory emf) Retrieve the shared server session from the EMF.
static boolean	isEclipseLink(EntityManager em) Verify if the JPA provider is EclipseLink.
static boolean	isEclipseLink(EntityManagerFactory emf) Verify if the JPA provider is EclipseLink
static boolean	isEclipseLink(Query query) Verify if the JPA provider is EclipseLink
static boolean	isReportQuery(Query query) Determine if the JPA query is a EclipseLink ReportQuery.
static void	loadUnfetchedObject(FetchGroupTracker entity) If the object has a fetch group then the whole object is read in.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JpaHelper

public JpaHelper()

Method Detail

isEclipseLink

public static boolean isEclipseLink(EntityManager em)

Verify if the JPA provider is EclipseLink. If you are in a container and not in a transaction this method may incorrectly return false. It is always more reliable to check isEclipseLink on the EMF or Query.

isEclipseLink

public static boolean isEclipseLink(EntityManagerFactory emf)

Verify if the JPA provider is EclipseLink

isEclipseLink

public static boolean isEclipseLink(Query query)

Verify if the JPA provider is EclipseLink

isReportQuery

public static boolean isReportQuery(Query query)

Determine if the JPA query is a EclipseLink ReportQuery. Useful for frameworks that want to determine which get_X_Query method they can safely invoke.

getReportQuery

public static ReportQuery getReportQuery(Query query)

Access the internal EclipseLink query wrapped within the JPA query. A EclipseLink JPA created from JP QL contains a ReportQuery if multiple items or a non-entity type is being returned. This method will fail if a single entity type is being returned as the query is a ReadAllQuery.

See Also:

getReadAllQuery(javax.persistence.Query)

getDatabaseQuery

public static DatabaseQuery getDatabaseQuery(Query query)

Access the internal EclipseLink query wrapped within the JPA query.

getReadAllQuery

public static ReadAllQuery getReadAllQuery(Query query)

Access the internal EclipseLink query wrapped within the JPA query. A EclipseLink JPA created from JP QL only contains a ReadAllQuery if only a single entity type is being returned. A ReadAllQuery is the super class of a ReportQuery so this method will always work for either a ReportQuery or ReadAllQuery.

createQuery

public static Query createQuery(DatabaseQuery query,
                                EntityManager em)

Create a EclipseLink JPA query dynamically given a EclipseLink query.

getEntityManager

public static JpaEntityManager getEntityManager(EntityManager entityManager)

Convert a JPA entityManager into a EclipseLink specific one. This will work both within a JavaSE deployment as well as within a container where the EntityManager may be wrapped. In the case where the container is not in a transaction it may return null for its delegate. When this happens the only way to access an EntityManager is to use the EntityManagerFactory to create a temporary one where the application manage its lifecycle.

getEntityManagerFactory

public static org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl getEntityManagerFactory(EntityManagerFactory emf)

Given a JPA EntityManagerFactory attempt to cast it to a EclipseLink EMF.

getServerSession

public static Server getServerSession(EntityManagerFactory emf)

Retrieve the shared server session from the EMF.

createEntityManagerFactory

public static EntityManagerFactory createEntityManagerFactory(Server session)

Create a EclipseLink EMF given a ServerSession that has already been created and logged in.

createEntityManagerFactory

public static org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl createEntityManagerFactory(java.lang.String sessionName)

Create a EclipseLink EMF using a session name and sessions.xml. This is equivalent to using the EclipseLink.session-xml and EclipseLink.session-name PU properties with the exception that no persistence.xml is required. The application would be required to manage this singleton EMF.

loadUnfetchedObject

public static void loadUnfetchedObject(FetchGroupTracker entity)

If the object has a fetch group then the whole object is read in.