entitymanager

I have Java EE application with about 10 EntityManagers (number of EMs will probably increase). My application also contains many stateless, statefull and message driven beans. Rather than inject in each bean my EMs with @PersistenceContext (and 2 methods to detect which EM to use for user), I probably store all of that inside a singleton bean and access it with others beans. Like that, no worries about maintainability. Nevertheless, is it thread-safe to store EMs inside one singleton bean? Can a bottleneck appear? Another solution is to create an abstract class and all beans will extend it.

I met the problem of persisting element to database using EntityManager. Based on the answers I found, I tried those 4 ways in my DaoJpa to do such thing but still failed. Here I attached the four ways I tried: Code in Controller part: @Transactional SmartProduct smartProduct = new SmartProduct(); smartProduct.setName("Dove Soap"); smartProductDao.persist(smartProduct); 1. DaoJpa: @Transactional public void persist(SmartProduct smartProduct) { entityManager.persist(smartProduct); Doesn't work! 2. @Transactional public void persist(SmartProduct smartProduct) { entityManager.persist(smartProduct

I have a Spring + Hibernate + JPA app. The user, when logging in, can choose from a list of DB's to connect to (these are the requirements). All the DB's have the same schema, so the same entities and DAO's will be used. Right now I have one EntityManager (been working with one database for the moment) that is injected in the DAO like this: @PersistenceContext private EntityManager entityManager; Is there any way to have the DAO receive the entityManager automatically (managed by Spring) based on a parameter/property received from the service layer ? (The web layer sends a kind of context, and

my question is why flush doesn't work : public void ejbService(){ Customer c = em.find(Customer.class,1); c.setName("newName"); em.flush(); //at this point when I query mysql table I can not see "newName" thread.sleep(10000); c.setName("anotherName"); } After finishing the method I see "anotherName" in the db also I check it with em.find(Customer.class,1,Lock.None); but still not work RGDS You're flushing, but you're not committing - or otherwise ending the transaction / session which is likely configured for auto-commit. Yes, after calling flush() , the DBMS is now aware of your data - but

I need to process a CSV file and for each record (line) persist an entity. Right now, I do it this way: while ((line = reader.readNext()) != null) { Entity entity = createEntityObject(line); entityManager.save(entity); i++; } where the save(Entity) method is basically just an EntityManager.merge() call. There are about 20,000 entities (lines) in the CSV file. Is this an effective way to do it? It seems to be quite slow. Would it be better to use EntityManager.persist() ? Is this solution flawed in any way? EDIT It's a lengthy process (over 400s) and I tried both solutions, with persist and

I'm currenetly trying hard to delete an entity, that is involved in various relations (Only @ManyToOne ) - However, Hibernate does not delete anything - after calling em.remove everything remains unchanged. I have 5 entities ( E1 - E5 ), referencing the entity ( E6 ) in question like this: @Entity public class EX { @OneToMany(mappedBy = "eX", fetch = FetchType.EAGER, cascade = { CascadeType.PERSIST, CascadeType.REMOVE }) private Set<E6> e6s; } E6 itself has the reverse @ManyToOne Relations: public class E6{ @ManyToOne(optional = false) private E1 e1; @ManyToOne(optional = false) private E2 e2;

I'm using Spring + Hibernate + JPA and I have a situation where I can't get my entities to persist to the database. I've set up a service class that is annotated with @Transactional. It uses a DAO that contains an injected EntityManager. When I call the function on the service object I see a bunch of selects for the reads the DAO is doing, but no updates/deletes as a result of merges and removes issued by my DAO. Surely there's something wrong with my setup, but I can't see it. persistence.xml <persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001