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Difference between EntityManager and SessionFactory [message #726935] Mon, 19 September 2011 21:54 Go to next message
Eclipse UserFriend
Hello All:

I am new to JPA and often while reading documentation, I see different mechanisms to create queries. One with EntityManager and the other mechanism deals with Sessions. Which is the preferred mechanism?


Session example:
---------------
ReadAllQuery query = new ReadAllQuery(Employee.class);
query.setJPQLString("SELECT OBJECT(emp) FROM Employee emp");
...
List employees = (List)session.executeQuery(query);

Entity Manager example:
----------------------
factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
EntityManager em = factory.createEntityManager();
// Read the existing entries and write to console
Query q = em.createQuery("select t from Todo t");
List<Todo> todoList = q.getResultList();
for (Todo todo : todoList) {
System.out.println(todo);
}

What is the preferred mechanism? Can someone throw somelight?

Thanks
Sridhar
Re: Difference between EntityManager and SessionFactory [message #728085 is a reply to message #726935] Thu, 22 September 2011 10:06 Go to previous messageGo to next message
Eclipse UserFriend
JPA defines the EntityManager interface and it should be used with JPA whenever possible.

The Session API is EclipseLink's native API that existed pre-JPA.

Using JPA is recommend, as it is the standard. If required, you can still access the EclipseLink Session from the JPA EntityManager to access advanced functionality.

Re: Difference between EntityManager and SessionFactory [message #728142 is a reply to message #728085] Thu, 22 September 2011 11:43 Go to previous messageGo to next message
Eclipse UserFriend
Thanks James. It clears a lot of confusion for me. Thanks again.
(no subject) [message #728163 is a reply to message #728085] Thu, 22 September 2011 11:43 Go to previous message
Eclipse UserFriend
Thanks James. It clears a lot of confusion for me. Thanks again.
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