JpaHelper (EclipseLink 2.5.1, build 'v20130918-f2b9fc5' API Reference)

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

Constructors
Constructor and Description

JpaHelper()

Constructors
Constructor and Description
`JpaHelper()`

Method Summary

Methods
Modifier and Type	Method and Description
`static EntityManagerFactory`	`createEntityManagerFactory(Server session)` Create a EclipseLink EMF given a ServerSession that has already been created and logged in.
`static EntityManagerFactory`	`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 DatabaseSession`	`getDatabaseSession(EntityManagerFactory emf)` Retrieve the shared database session from the EMF.
`static JpaEntityManager`	`getEntityManager(EntityManager entityManager)` Convert a JPA entityManager into a EclipseLink specific one.
`static JpaEntityManagerFactory`	`getEntityManagerFactory(EntityManager em)` Given an EntityManager return the EntityManagerFactory that created it.
`static JpaEntityManagerFactory`	`getEntityManagerFactory(EntityManagerFactory emf)` Given a JPA EntityManagerFactory attempt to cast it to a EclipseLink EMF.
`static org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl`	`getEntityManagerFactory(org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl emf)` Deprecated.
`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 SessionBroker`	`getSessionBroker(EntityManagerFactory emf)` Retrieve the shared session broker 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(org.eclipse.persistence.internal.jpa.EntityManagerFactoryImpl emf)
```
    Deprecated.
    
    Given a JPA EntityManagerFactory attempt to cast it to a EclipseLink EMF. Although this method currently returns an instance of EntityManagerFactoryImpl, it is recommended that users cast to JpaEntityManagerFactory. Future versions of EclipseLink will return that interface from this method instead
    
    See Also:
    JpaEntityManagerFactory
  - getEntityManagerFactory
```
public static JpaEntityManagerFactory getEntityManagerFactory(EntityManagerFactory emf)
```
    Given a JPA EntityManagerFactory attempt to cast it to a EclipseLink EMF.
    
    See Also:
    JpaEntityManagerFactory
  - getEntityManagerFactory
```
public static JpaEntityManagerFactory getEntityManagerFactory(EntityManager em)
```
    Given an EntityManager return the EntityManagerFactory that created it. This method must be called on an open entity manager and will return null if called on a closed entityManager. This method will return null for non-EclipseLink EntityManagers.
    
    See Also:
    JpaEntityManagerFactory
  - getDatabaseSession
```
public static DatabaseSession getDatabaseSession(EntityManagerFactory emf)
```
    Retrieve the shared database session from the EMF.
  - getServerSession
```
public static Server getServerSession(EntityManagerFactory emf)
```
    Retrieve the shared server session from the EMF.
  - getSessionBroker
```
public static SessionBroker getSessionBroker(EntityManagerFactory emf)
```
    Retrieve the shared session broker 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 EntityManagerFactory 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.

Class JpaHelper

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

JpaHelper

Method Detail

isEclipseLink

isEclipseLink

isEclipseLink

isReportQuery

getReportQuery

getDatabaseQuery

getReadAllQuery

createQuery

getEntityManager

getEntityManagerFactory

getEntityManagerFactory

getEntityManagerFactory

getDatabaseSession

getServerSession

getSessionBroker

createEntityManagerFactory

createEntityManagerFactory

loadUnfetchedObject