hibernate left join lazycollection untouchable

Question

I got something like this:

Criteria crit = session.createCriteria(Parent.class,"p");
parentsList = crit.createCriteria(
    "childSet","c",
    JoinType.LEFT_OUTER_JOIN,
    Restrictions.eq("jt.2ndParentDto.pk2ndParentDto", pk2ndParent))
    .list();

My query returns a list of parents with one child each or none, i already tested the logged query directly, so i am pretty sure of it.

I have to retrieve a list of children, so i am adding the parent and creating the ones missing.

List<ChildDto> list=new ArrayList<ChildDto>();
for(ParentDto item:parentsList){
    Iterator<ChildDto> it=item.getChildSet().iterator();
    if(it.hasNext()){
        ChildDto dto = it.next();
        dto.setParentDto(item);
        list.add(dto);
    }
    else{
        ChildDto dto = new ChildDto();
        dto.setParentDto(item);
        list.add(dto);
    }
}
return list;

By calling item.getChildSet().iterator() hibernate loads the entire collection so i cannot call item.getChildSet().iterator().hasNext to check if there is something in the set, and i cannot call item.getChildSet().size() neither for the exact same reason...

then how?, what else is there?, i am currently out of ideas, how can i get the only item of the set if there is one?

Update : I just tried Extra lazy loading, but it doesn't change for better or worse...

item.getChildSet().iterator() still causes to load the entire collection.

And when i do item.getChildSet().size() hibernate triggers a count... so i always get size of the entire collection (no use).

And that's pretty much it =/

Update : I got it working with a projection by getting a list of Object[] items, and manually creating the classes. I don't like to do this because, with a change to the Hbm, you're forced to maintain queries of this kind, so i try to avoid this as much as possible.

Answer 1

我不确定我是否完全了解您的要求，但是我认为您正在寻找的是Hibernate的“额外懒惰”集合，该集合可让您获取有关集合的一些信息（包括大小），而无需初始化整个集合，以及将大型集合批量（而不是一次全部）加载到内存中。

Answer 2

Can you change the query to return the child records instead? That way you won't get the whole collection. I am not begin clear. Can you just get the child objects from the database, then call something like getParent() to get the parents you need?