eclipselink

问题 'Flex fields' is a term for altering a table at the customer site to add extra columns to a table to hold custom pieces of information about that table's entity. I was wondering if anyone has dealt with supporting this mechanism with jpa, specifically eclipselink. We wish to do this because we allow filtering of the base rows based on values in these customer specified fields, and having these fields in an association table causes multiple alias joins to this auxilliary table. An obvious

问题 Question pretty much says it all. Is there an equivalent for org.hibernate.Version.getVersionString() in EclipseLink? Why isn't there a portable (JPA) way to query provider information in general? 回答1: Never used it but from the Eclipselink javadoc you could try the following class: org.eclipse.persistence.Version 回答2: There is a static class and static method to get this information. Example: How to print in java code AbstractSessionLog.getLog().log(SessionLog.INFO, DatabaseLogin.getVersion(

问题 Is it possible to do indexed element access in JPQL like in HQL : select o from Order o where o.items[0].id = 1234 I couldn't find something related in the JPA 2 specs, I am targeting EclipseLink JPA here, so if you come up with an EclipseLink solution, that's ok as well, although a JPQL standard solution is preferred. 回答1: The INDEX function should do the trick (actually I tested it and it does): SELECT o FROM Order o JOIN o.items i WHERE i.id = 1234 AND INDEX(i) = 0 From the JPA 2.0

问题 This is my first time really playing around with Java development using Eclipse. I am trying to use EclipseLink's implementation of the JPA. I moved all of my entities into a separate package "entities". I have the persistence.xml in a separate JPA project called "dataModeling". Everything builds and runs fine. Just about every project depends on my entities. However, I'm seeing a warning Class javax.persistence.Entity not found - continuing with a stub. , etc. showing up because the

问题 I'd like to create one Bundle that is able to use Java Persistence. To achieve this, I've created a plugin project within Eclipse. In my project, I've created a persistence.xml file into META-INF. I've aslo added in my MANIFEST.mf (into the depencies) those 3 packages : javax.persistence.jar org.eclipse.persistence.jar org.eclipse.persistence.jar Then, in my Activator I use this lines to create an EntityManager : factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);

问题 I have one jar library A (or project in eclipse), which has it's own persistence unit (META-INF/persistence.xml) and some entity classes, and another project (B) using this one. In project B there is also persistence unit and entity classes. In project B I need to use both entity classes from project A and B. But if I set "A" as persistence unit name, EntityManager cannot create named query if this query is in entity from project B. If I set "B" as persistence unit name, it cannot create

问题 I have a main thread where I get an object from database, then close the EntityManager, then put the object into a queue. A worker thread makes some business with the object, then puts it into a finished queue. Then the main thread gets the object from the finished queue and merges the object: EntityManager em = entityManagerFactory.createEntityManager(); em.getTransaction().begin(); // Print the primary key ID of the object, // it is NOT empty yes it exists in the db. em.merge(myObject); em

问题 I have a main thread where I get an object from database, then close the EntityManager, then put the object into a queue. A worker thread makes some business with the object, then puts it into a finished queue. Then the main thread gets the object from the finished queue and merges the object: EntityManager em = entityManagerFactory.createEntityManager(); em.getTransaction().begin(); // Print the primary key ID of the object, // it is NOT empty yes it exists in the db. em.merge(myObject); em

问题 I am using EclipseLink in my web application, and I am having a hard time gracefully catching and handling Exceptions it generates. I see from this thread what seems to be a similar problem, but I don't see how to work around or fix it. My code looks like this: public void persist(Category category) { try { utx.begin(); em.persist(category); utx.commit(); } catch (RollbackException ex) { // Log something } catch (HeuristicMixedException ex) { // Log something } catch

问题 I am using MOXy as JAXB Implementation but somehow I would like to show the Implementation Name (e.g. Moxy) and the version number on some admin screen (dynamically). How can I retrieve that info from JAXB? Cheers 回答1: You could do something like the following to figure out the JAXB impl being used: import javax.xml.bind.JAXBContext; public class Demo { private static final String MOXY_JAXB_CONTEXT = "org.eclipse.persistence.jaxb.JAXBContext"; private static final String METRO_JAXB_CONTEXT =