[hibernate-issues] [Hibernate-JIRA] Created: (HHH-6518) Request malformed on a left fetch join subItem.myCollection (double outer join) : uncorrect fromElementList, can't find the associated collectionOwner and initialize a proxy on an empty fetched collection

[Quentin Ambard (JIRA)]

Request malformed on a left fetch join subItem.myCollection (double outer join) : uncorrect fromElementList, can't find the associated collectionOwner and initialize a proxy on an empty fetched collection 
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                 Key: HHH-6518
                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-6518
             Project: Hibernate Core
          Issue Type: Bug
          Components: core, query-sql
    Affects Versions: 4.0.0.Beta4, 3.6.6
            Reporter: Quentin Ambard
         Attachments: hibernateTestCase.tar.gz

There is an error fetching a collection of a subitem. 
This affect empty collections : a proxy is intialized on the collection, even fetched. Accessing to this collection fire a new request.

Here is a simple mode. Please see test case for complete implementation:

@Entity
@Table( name = "ITEM" )
public class Item {
	@Id
	@GeneratedValue
    private Long id;

    @OneToOne(cascade = { CascadeType.ALL }, optional = true, fetch = FetchType.LAZY, orphanRemoval = true)
    @JoinColumn(name = "SUB_ITEM_ID")
    private SubItem subItem ;

...
}

public class SubItem {
	@Id
	@GeneratedValue
    private Long id;
	
	
    @ElementCollection(targetClass = String.class, fetch = FetchType.LAZY)
    @CollectionTable(name = "PHONES")
    @Column(name = "PHONE", nullable = false)
	private List<String> phones  ;
...
}

the following hql request "from Item i left join fetch i.subItem left join fetch i.subItem.phones" generates this sql request :

select item0_.id as id2_0_, subitem1_.id as id1_1_, item0_.SUB_ITEM_ID as SUB2_2_0_, phones3_.SubItem_id as SubItem1_1_0__, phones3_.PHONE as PHONE0__, phones3_.SubItem_id as SubItem1_1_0__, phones3_.PHONE as PHONE0__ 
from ITEM item0_ 
left outer join SUB_ITEM subitem1_ on item0_.SUB_ITEM_ID=subitem1_.id 
left outer join SUB_ITEM subitem2_ on item0_.SUB_ITEM_ID=subitem2_.id 
left outer join PHONES phones3_ on subitem2_.id=phones3_.SubItem_id

There is an extra left outerjoin.
QueryClassLoader.initialize(SelectClause selectClause) can't find the collectionOwner for the PHONES collection : 
collectionFromElement.getOrigin()is about the second left outer join : "SUB_ITEM subitem2_ on item0_.SUB_ITEM_ID=subitem2_.id" and the fromElementList is based on the first outer join "subitem1_ on item0_.SUB_ITEM_ID=subitem1_.id".

The following hql request doesn't work either :
from Item i left join fetch i.subItem s left join fetch s.phones
Request is correctly generated, but the left outer join collectionPersisters is null 
java.lang.NullPointerException
	at org.hibernate.loader.BasicLoader.isBag(BasicLoader.java:97)
	at org.hibernate.loader.BasicLoader.postInstantiate(BasicLoader.java:76)
	at org.hibernate.loader.hql.QueryLoader.<init>(QueryLoader.java:120)
	at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:204)
...

see attached test case for full stack

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