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POJPA behaviour
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copied!<p>I have some trouble understanding a JPA behaviour. Mabye someone could give me a hint. Situation:</p> <p>Product entity:</p> <pre><code>@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; } } </code></pre> <p>Resource entity:</p> <pre><code>@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; } } </code></pre> <p>ProductResource Entity: This is a JoinTable (association class) with additional properties (amount). It maps Product and Resources.</p> <pre><code>@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; } } </code></pre> <p>This is the Session Bean (running on glassfish).</p> <pre><code>@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); } } </code></pre> <p>I call the session Bean from a java client:</p> <pre><code>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)); } } </code></pre> <p>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!?</p> <p>Any help is appreciated</p> <p>Thanks</p> <p>Marcel</p>

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