persistence

Why does JPA require a no-arg constructor for domain objects ? I am using eclipselink and just got this exception during deployment. Exception [EclipseLink-63] (Eclipse Persistence Services-1.1.0.r3639-SNAPSHOT): org.eclipse.persistence.exceptions.DescriptorException Exception Description: The instance creation method [com.me.model.UserVO.<Default Constructor>], with no parameters, does not exist, or is not accessible. Internal Exception: java.lang.NoSuchMethodException: com.me.model.UserVO.<init>() Descriptor: RelationalDescriptor(com.me.model.UserVO --> [DatabaseTable(user)]) Because it

I'm using Persistence unit and Entity classes from Database, all in a JavaFx fxml Application, I succeeded importing all my tables as entities in my Model, the proble is that I get an exceptions and errors when I try to insert into an entity, here's my entire code public class SampleController implements Initializable { @PersistenceContext(unitName="RawdaPU") private EntityManager em; @FXML private Label label; @FXML private void handleButtonAction(ActionEvent event) { Moyendidactique moyenDidactique = new Moyendidactique("1", "moyen1", "Type1"); em.persist(moyenDidactique); em.close(); }

I have basically two Entities Entity1 and Entity2 . Entity1 contains this bit of Code: @OneToMany(cascade=CascadeType.PERSIST) @OrderColumn List<Entity2> e = new LinkedList<Entity2>(); and Entity2 contains some stuff, but nothing relevant. I want to add some instances to the list e , and most importantly i want to add some duplicates (the same reference) twice or more to the list. Still i want JPA to persist both and i want JPA to persist the Order of the list. So far this works, if i add only unique items. If i add a duplicate, JPA actually wants to persist the correct data (ID od Entity1, ID

Is it possible to use hibernate as Glassfish's persistence provider and if so HOW? Guss While I'm not an expert on either Glassfish or Hibernate, I think you'd probably find this interesting: Instructions on using Hibernate in Glassfish The link provided by Guss to hibernate.org has expired. Here's a google cache dated Feb 20, 2010. As noted in a previous version of the linked wiki page, it is preferable to keep the hibernate libraries within your .ear / .war rather than the Glassfish install dir so that different applications can use their own version of Hibernate. Modern How-To To use

I am just starting to model the data for a new project, which must be persistable. Looks like the most natural OO model will have lots of nested .Net generics. Lists of objects, and these objects will also contain Lists of other generic types, and so on, nested at least three levels deep. Ideally, I'd like to just design the data model in an OO fashion, and am hoping that there is an ORM that will allow me to just (magically ;-) persist the whole model to a relational database without me having to worry about the relational schema at all. I'm willing to sacrifice performance for ease of