Is possible to change runtime lazy query transaction as eage

Grinvon · **Joined:** Tue Dec 18, 2007 9:15 am **Posts:** 14

By default hibernate works in lazy mode transaction. Sometimes I need to extract all related objects in eager mode, but I don´t want to declare it as a annotation (my annotation is in lazy mode). Can I sometimes bring these datas as eager? How?

Thanks!

Irons UK · **Posted:** Thu Feb 07, 2008 8:48 am

Grinvon wrote:

By default hibernate works in lazy mode transaction. Sometimes I need to extract all related objects in eager mode, but I don´t want to declare it as a annotation (my annotation is in lazy mode). Can I sometimes bring these datas as eager? How?

Thanks!

I don't think there's anything in hibernate to do this, but you could always call size() on the collection to force a load.

Grinvon · **Joined:** Tue Dec 18, 2007 9:15 am **Posts:** 14

Aye. We can use size() and others methods. But there is a problem. I want that hibernate do not know the collection name.

If I have Entity 1 -> Entity 2 -> Entity 3 - Entity 4.

I want to bring Entity 1 instance, and when I will persist in another EM, it knows all related objects from Entity 1. So Entity 1 brings all related objects with him.

I used NamedQuery to do it, but it don´t appear to be generic, I want a generic soluction for any case to simulate a onfly eager fetch mode.

Grinvon · **Joined:** Tue Dec 18, 2007 9:15 am **Posts:** 14

I have used this solution for my issue.

All my entities have a commun superclass.

This superclass have one public abstract method that all subclass need to implement.

See:

Code:

@Transient
public Collection all;

public abstract Collection getAll();

All subclass implements getAll. This method add all dependent object from one entity to a collection.

When I persist Entity 1, re gets all related objects.

For example I have:

Entity 1 class:

Code:

@OneToMany(cascade=CascadeType.ALL, mappedBy="entity1",fetch=FetchType.LAZY)
private List<Entity2> entities2;

    @Override
    public Collection getAll() {
        if (all == null)
            all = new ArrayList();
        
        if (entities2 != null && entities2.size() > 0) {
            for (Entity2 et2 : entities2) {
                all.add(et2);
                et2.getAll();
            }
        }
        return all;
    }

In Entity 2 class:

Code:

    @ManyToOne(cascade=CascadeType.ALL, fetch=FetchType.LAZY)
    private Entity1 entity1;
    
    @OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY)
    private List<Entity3> entities3;

    @Override
    public Collection getAll() {
        if (all == null)
            all = new ArrayList();
        
        if (entities3 != null && entities3.size() > 0) {
            for (Entity3 et3 : entities3) {
                all.add(et3);
                et3.getAll();
            }
        }
        return all;
    }

And so on...

Thus I can handle all instances, all dependents objects. This is not the most clear and elegant solution, but this is the solution that I thought. I hope I was clear, cuz my english is not so good.

If someone else have another solution, please take a time and post here, will help others. Thanks all.

Grinvon · **Joined:** Tue Dec 18, 2007 9:15 am **Posts:** 14

I think in actual state, JPA 1.0 do not support runtime changes about FetchMode. I hope that 2.0 can do it as well and improve "new" things that hibernate have been supported.