App Engine JPA Datastore delete entity - google-app-engine

Question

im trying to build a google app engine projekt with JPA, JAX-RS and JAX-B. My POST and GET Methods work, but my DELETE method doesn't delete the data.
Resource
#DELETE
#Path("card/{id}")
public void deleteCardById (#PathParam ("id") Long id) {
Service.removeCard(id);
}
Service
public static void removeCard(Long id) {
EntityManager em = EMFService.get().createEntityManager();
Card emp = findCard(id);
if (emp != null) {
em.remove(emp);
}
em.close();
}
public static Card findCard(Long id) {
EntityManager em = EMFService.get().createEntityManager();
Card card = em.find(Card.class, id);
em.close();
return card;
}
Entity
#XmlRootElement
#Entity
public class Card {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
Long id;
String begriff;
String tabu1;
String tabu2;
String tabu3;
public Card(String begriff, String tabu1, String tabu2, String tabu3) {
super();
Begriff = begriff;
Tabu1 = tabu1;
Tabu2 = tabu2;
Tabu3 = tabu3;
}
public Card() {
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getBegriff() {
return Begriff;
}
public void setBegriff(String begriff) {
Begriff = begriff;
}
public String getTabu1() {
return Tabu1;
}
public void setTabu1(String tabu1) {
Tabu1 = tabu1;
}
public String getTabu2() {
return Tabu2;
}
public void setTabu2(String tabu2) {
Tabu2 = tabu2;
}
public String getTabu3() {
return Tabu3;
}
public void setTabu3(String tabu3) {
Tabu3 = tabu3;
}
#Override
public String toString() {
return "Card [Begriff=" + Begriff + ", Tabu1=" + Tabu1 + ", Tabu2="
+ Tabu2 + ", Tabu3=" + Tabu3 + "]";
}
When i Debug the app it gives the correct Object to the remove function. But it just don't remove the data ...

Answer 1

You mean you're using v1 of the GAE JPA plugin, and you don't bother putting a transaction around your remove (so the remove is delayed until the next transaction ... which never happens)?
Obviously you could either put a transaction around the remove, or better still you use v2 of the GAE JPA plugin

Answer 2

I was facing similar issue too. the JPA delete actually deletes the entity in the datastore,but it doesn't delete the entity from the JPA Cache.. You page is actually using the JPA Cached result list to display..
The way I used to resolve the issue is to have the JPA Cache cleared every time after a delete.
Sample Code would be something like this:
EM.getTransaction().begin();
EM.remove(current_record);
EM.getTransaction().commit();
EM.getEntityManagerFactory().getCache().evictAll();

Answer 3

ok i think i should write it like this
*edit the problem was the findCard function, i think because of the secone instance of the EntityManager. I chnaged it without using this method to this and now it works.
public static void removeCard(Long id) {
EntityManager em = EMFService.get().createEntityManager();
EntityTransaction tx = em.getTransaction();
try {
tx.begin();
Card card = em.find(Card.class, id);
if (card != null) {
em.remove(card);
}
tx.commit();
} finally {
if (tx.isActive()) {
tx.rollback();
}
em.close();
}
}