Revision as of 16:42, 10 March 2009

Updated EntityManager / Query APIs

JPA 2.0 Root | Enhancement Request

Issue Summary

In JPA 2.0 the specification extends EntityManager and Query APIs. New APIs have been added for getting supported properties and getting the owning Entity Manager Factory.

A new operation 'clear' was also added including a new Cascade Type. Calling clear on an Entity allows the user to remove an Entity and cascaded related entities from the persistence context. Effectively an unregister call.

See JPA 2.0 ED section 3.1.1 and 3.2.6 for details.

New methods are added to EM API in the latest spec. Here are the new methods that have to be implemented:

find(Class <T> entityClass, Object primaryKey, Map<String,Object> properties)

refresh(Object entity, Map<String,Object> properties)

detach(Object entity)

setProperty(String propertyName,Object value)

General Solution

The implementation of this functionality should be straight forward.

Work Required

1. Develop test for testing new non-pessimistic locking APIs

   approx 2 days

2. Update Processing to

   approx 3 days - clear(Object entity)

   approx 2 days - remaining APIs

   approx 2 days - Query Hints

Work Completed

Implementation of the following functions have been completed so far in EM API Update

1. public Map<String,Object> getProperties();
2. public Set<String> getSupportedProperties();
3. public void clear(Object entity);
4. public <T> T unwrap(Class<T> cls);
5. public EntityManagerFactory getEntityManagerFactory();
6. public LockModeType getLockMode(Object entity);

Here are the implementation details described briefly of the 'getLockMode(Object entity)' method -- In EclipseLink, optimistically and pessimistically locked objects are tracked in 'getOptimisticReadLockObjects()' and 'getPessimisticReadLockObjects()' . The 'getOptimisticReadLockObjects()' returns a map that contains boolean as value . The 'getPessimisticReadLockObjects()' returns a map that contains an object as value. When an object is locked , the following has to be checked to determine the lockmodetype-

1. OPTIMISTIC --- getOptimisticReadLockObjects() should contain the entity with boolean value 'false'
2. PESSIMISTIC ---getPessimisticReadLockObjects() should contain the entity
3. OPTIMISTIC_FORCE_INCREMENT ---- getOptimisticReadLockObjects() should contain the entity with boolean value 'true'

   and 'getPessimisticReadLockObjects()' should NOT contain the entity

4. PESSIMISTIC_FORCE_INCREMENT---getOptimisticReadLockObjects() should the entity with boolean value 'true'

   and 'getPessimisticReadLockObjects()' should contain the entity.

5. NONE --- see [[1]

As discussed , when getLockMode(entity) is called on an entity that is removed, it throws 'IllegalArgumentException.' This has been taken care by checking whether the entity is contained in the active unit of work or not.