[jboss-user] [EJB 3.0] - Fetch join with collection

[jan_bar]

Hi,

I can fetch join lazy relation that returns single result, but for collection it doesn't work correctly.

I have Attribute.java:

  | @Entity
  | public class Attribute implements Serializable {
  | 
  | 	private Long id;
  | 
  | 	private List<Resource> resources = new ArrayList<Resource>();
  | 
  | 	public Attribute() {
  | 		super();
  | 	}
  | 
  | 	@Id
  | 	@GeneratedValue
  | 	public Long getId() {
  | 		return id;
  | 	}
  | 
  | 	public void setId(Long id) {
  | 		this.id = id;
  | 	}
  | 
  | 
  | 	@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
  | 	public List<Resource> getResources() {
  | 		return resources;
  | 	}
  | }
  | 

and Resource.java:

  | @Entity
  | public class Resource implements Serializable {
  | 	private Long id;
  | 
  | 	private int resourceSize = 0;
  | 
  | 	public Resource() {
  | 		super();
  | 	}
  | 
  | 	@Id
  | 	@GeneratedValue
  | 	public Long getId() {
  | 		return id;
  | 	}
  | 
  | 	private void setId(Long id) {
  | 		this.id = id;
  | 	}
  | 
  | 	public int getResourceSize() {
  | 		return resourceSize;
  | 	}
  | 
  | 	public void setResourceSize(int resourceSize) {
  | 		this.resourceSize = resourceSize;
  | 	}
  | }
  | 

and a finder:

  | public List<Attribute> findWithResource(int resourceSize) {
  | 	return em.createQuery(
  | 		"SELECT ta FROM Attribute ta INNER JOIN FETCH ta.resources r" +
  | 		" WHERE r.resourceSize = :resourceSize")
  | 		.setParameter("resourceSize", resourceSize)
  | 		.getResultList();
  | }
  | 

This should return all attributes that have resource of requested resourceSize with fetched resources. 

Database content:
Attribute1: resource1 (resourceSize = 1), resource2 (resourceSize = 1), resource3 (resourceSize = 1)
Attribute2: resource1 (resourceSize = 1), resource2 (resourceSize = 1), resource3 (resourceSize = 1)

The query generated by EJB3 looks correctly:

  | select  ...
  | from Attribute attribute0_
  | 	inner join Attribute_Resource resources1_ on attribute0_.id=resources1_.Attribute_id
  | 	inner join Resource resource2_ on resources1_.resources_id=resource2_.id
  | where resource2_.resourceSize=?
  | 

When I call findWithResource(1), I expect to get two Attributes, each with the three resources loaded. Instead I get six Attributes, each with three resources loaded.

I this bug inside my query, unsupported feature or bug in EJB3?

Thank you for your care, Jan

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