Hi,
Please take a look at Class A

class A {

@Column(name = "type")
private String type;

@OneToMany(...)
@JoinColumn(name = "foo")
private Set<B> children = new HashSet<B>();


}


I want to load children only if type belongs to certain type.

There may be many types, let's say A, B, C, D, E.

If type == 'C' then I want to load A's children B.

How to achieve this using Filter?

I did something where I was setting a filter that works with an attribute of B.

I want to write a filter that works with an attribute of A so that based on "type" I want to load A's children.

Thanks

What if you subclass A and use type as a discriminator? Then you could define the association for the subclasses that have a specific type.



Farzad-

Is this the only way? Can you please let me know if there are any alternative approaches?

I try to use a subclass as suggested by you.

Thanks,
Servlette

I can't think of any other way but that does not mean there is no other way. I would also like to know if this can be handled in a less painful way.


Farzad-

The scenario goes something like this:

Take a look at class A I posted before and then take a look at C below.


class C {

@ManyToOne(...)
@JoinColumn(name = "bar")
private A a;

}

I am trying to load class C that is mapped to a table.
When "C" gets loaded it loads "A" and "A" loads "B".

I want to control loading of B in A as for a particular type there are 100's of B.

I want an HQL or something thru which I want to take control over B's loading.

I am clueless as to how to address this as I am relatively a new Hibernate user.

Your experience or knowledge if you share with me will be really helpful.



Thanks

The default behaviour in HQL is not to fetch relations unless a join fetch is specified so do your query in hql and you will be happy.



Farzad-

In my case,
the HQL goes something like this:

select * from C c where c.a.b.attr = "something";

For the sake of clarity I simpilfied the above query.

It loads C, A and all B.

During the select, I want to tell Hibernate, don't load B, if A.type = "foo";

Though B's fetch type is set to lazy in A, it loads B as I am doing something like c.a.b.attr = 'something' using joins.

Thanks

will only load Cs and nothing else. Lazy fetch instructions are not used here so it doesn't matter what you have put in your mapping.


Farzad-