JPA behaviour...
- by Marcel
Hi
I have some trouble understanding a JPA behaviour. Mabye someone could give me a hint.
Situation:
Product entity:
@Entity
public class Product implements Serializable {
...
@OneToMany(mappedBy="product", fetch=FetchType.EAGER)
private List<ProductResource> productResources = new ArrayList<ProductResource>();
....
public List<ProductResource> getProductResources() {
return productResources;
}
public boolean equals(Object obj) {
if (obj == this) return true;
if (obj == null) return false;
if (!(obj instanceof Product)) return false;
Product p = (Product) obj;
return p.productId == productId;
}
}
Resource entity:
@Entity
public class Resource implements Serializable {
...
@OneToMany(mappedBy="resource", fetch=FetchType.EAGER)
private List<ProductResource> productResources = new ArrayList<ProductResource>();
...
public void setProductResource(List<ProductResource> productResource) {
this.productResources = productResource;
}
public List<ProductResource> getProductResources() {
return productResources;
}
public boolean equals(Object obj) {
if (obj == this) return true;
if (obj == null) return false;
if (!(obj instanceof Resource)) return false;
Resource r = (Resource) obj;
return (long)resourceId==(long)r.resourceId;
}
}
ProductResource Entity:
This is a JoinTable (association class) with additional properties (amount). It maps Product and Resources.
@Entity
public class ProductResource implements Serializable {
...
@JoinColumn(nullable=false, updatable=false)
@ManyToOne(fetch=FetchType.EAGER, cascade=CascadeType.PERSIST)
private Product product;
@JoinColumn(nullable=false, updatable=false)
@ManyToOne(fetch=FetchType.EAGER, cascade=CascadeType.PERSIST)
private Resource resource;
private int amount;
public void setProduct(Product product) {
this.product = product;
if(!product.getProductResources().contains((this))){
product.getProductResources().add(this);
}
}
public Product getProduct() {
return product;
}
public void setResource(Resource resource) {
this.resource = resource;
if(!resource.getProductResources().contains((this))){
resource.getProductResources().add(this);
}
}
public Resource getResource() {
return resource;
}
...
public boolean equals(Object obj) {
if (obj == this) return true;
if (obj == null) return false;
if (!(obj instanceof ProductResource)) return false;
ProductResource pr = (ProductResource) obj;
return (long)pr.productResourceId == (long)productResourceId;
}
}
This is the Session Bean (running on glassfish).
@Stateless(mappedName="PersistenceManager")
public class PersistenceManagerBean implements PersistenceManager {
@PersistenceContext(unitName = "local_mysql")
private EntityManager em;
public Object create(Object entity) {
em.persist(entity);
return entity;
}
public void delete(Object entity) {
em.remove(em.merge(entity));
}
public Object retrieve(Class entityClass, Long id) {
Object entity = em.find(entityClass, id);
return entity;
}
public void update(Object entity) {
em.merge(entity);
}
}
I call the session Bean from a java client:
public class Start {
public static void main(String[] args) throws NamingException {
PersistenceManager pm = (PersistenceManager) new InitialContext().lookup("java:global/BackITServer/PersistenceManagerBean");
ProductResource pr = new ProductResource();
Product p = new Product();
Resource r = new Resource();
pr.setProduct(p);
pr.setResource(r);
ProductResource pr_stored = (ProductResource) pm.create(pr);
pm.delete(pr_stored);
Product p_ret = (Product) pm.retrieve(Product.class, pr_stored.getProduct().getProductId());
// prints out true ????????????????????????????????????
System.out.println(p_ret.getProductResources().contains(pr_stored));
}
}
So here comes my problem. Why is the ProductResource entity still in the List productResources(see code above). The productResource tuple in the db is gone after the deletion and I do newly retrieve the Product entity. If I understood right every method call of the client happens in a new persistence context, but here i obviously get back the non-refreshed product object!?
Any help is appreciated
Thanks
Marcel
