entitymanager

I'm new to JPA/OpenJPA and I noticed that if I don't call EntityManager.clear() after i persist entities I get an OutOfMemoryError (I keep adding new entities in a loop). I'm not sure if this is the expected behavior or it's just and OpenJPA 1.2.1 glitch. So, am I required to explicitly detach the entities myself? If I'm not, it's a good practice anyway? I don't have much experience with JPA. However this'll be useful - In JPA you must either: - Create a new EntityManager for each transaction. - Call clear() after each transaction to clear the persistence context. Depends how many objects you

I started using the new entity graph feature in JPA 2.1 to specify the Lazy collections that must be loaded. Consider following classes: @Entity @NamedQueries({ @NamedQuery(name="findWithFilterAttr","select a from A a where a.filterAttribute like :filter") }) @NamedEntityGraphs({ @NamedEntityGraph(name = "graph.childs", attributeNodes = @NamedAttributeNode("childs"))}) public class A{ @Id private long id; @OneToMany(mappedBy="parent") private List<B> childs; private String filterAttribute; } @Entity public class B{ @Id private long id; @ManyToOne private A parent; } When I execute the named

In my web applicaton I use OpenJPA on Apache Tomcat (TomEE)/7.0.37 server. I use Netbeans to auto generate class ("Entity Class from database..." and "Session Beans From Entity Class..."). At SessionBean (for example UserFacade) i want to get EntityManager: @Stateless public class UserFacade extends AbstractFacade<User> { @PersistenceContext(unitName = "CollDocPU") private EntityManager em; @Override protected EntityManager getEntityManager() { return em; } } but when i get it by above way I get null. When I make it by: @Override protected EntityManager getEntityManager() {

I'm trying to write a JUnit test for a Spring Roo project. If my test requires use of the entity classes, I get the following Exception: java.lang.IllegalStateException: Entity manager has not been injected (is the Spring Aspects JAR configured as an AJC/AJDT aspects library?) The Spring Aspects JAR looks to be configured correctly. In particular, I have the following in the pom.xml file: <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aspects</artifactId> <version>${spring.version}</version> </dependency> and <plugin> <configuration> <outxml>true</outxml>

I am not using Spring so I am creating an instance of EntityManager within a class. I used Hibernate-Eclipse reverse engineering to auto-generate the classes. These classes all has an instance of EntityManager. I am not 100% sure how Hibernate works with the EntityManager so I am wondering if it is okay that so many instances of this class (EntityManager) are made, for example, will there be problems with transactions? Should I just make a separate class that distributes a static instance of an EntityManager for all my other classes? or does it not matter? EDIT: I see there's something called

I'm a bit of a Java EE/EJB noob, but from the docs and other posts I've gathered you cannot query the database using the same entitymanager/session during entity validation. In general, the lifecycle method of a portable application should not invoke EntityManager or Query operations, access other entity instances, or modify relationships within the same persistence context.[43] A lifecycle callback method may modify the non-relationship state of the entity on which it is invoked. Translation please? This is pretty abstract...can it be explained in more concrete terms? It leads to more

EntityManager is not thread-safe by definition. Servlets specs says that in non-distributed environment and without implementing SingleThreadModel , there is only one servlet instance per definition . Therefore, in Java EE when you inject an EntityManager through the @PersistenceContext into Servlet's field - it's not thread safe: public class MyServlet extends HttpServlet { // Not thread-safe, should be using EMF instead. @PersistenceContext private EntityManager em; } Is this correct to say that even though the default scope of Spring beans is singleton, the EntityManager is thread-safe as