Can NHibernate load the result of a query per object?

sergunok · **Joined:** Tue Aug 23, 2005 8:15 am **Posts:** 45

IList<Test> result = criteria.List<Test>();

return ALL objects (fully and partially depends on laziness) correspond the query.

Can I ask NHibernate to give me only 1 next object of the result?
(Then I would like to use the object, call session.Evict(obj)
to free memory and ask NHibernate for next one).

Best regards,
Sergey

sergey · **Posted:** Thu May 24, 2007 2:36 pm

No, NHibernate does not support this feature (scrollable result sets).

sergunok · **Joined:** Tue Aug 23, 2005 8:15 am **Posts:** 45

Are there some architctualy difficulties to implement this?

sergey wrote:

No, NHibernate does not support this feature (scrollable result sets).

sergey · **Posted:** Thu May 24, 2007 3:10 pm

ADO.NET doesn't support it.

sergunok · **Joined:** Tue Aug 23, 2005 8:15 am **Posts:** 45

I deal with some kind of "Object" Data Mining task and try to use NHibernate as object provider. What do you think, is it good choice?
That what I need are: object oriented "select" queries and ability to manage the memory usage used for already selected object.

fabiob · **Joined:** Sat Dec 16, 2006 11:10 am **Posts:** 2

You can do something like:

Code:

DetachedCriteria crit = DetachedCriteria.For<Test>();
crit.SetMaxResults(1);

// you can also use the Criteria to eager fetch some lazy collections
crit.SetFetchMode("SubTests", FetchMode.Eager);

int i = 0;
while (true) {
  crit.SetFirstResult(i);
  IList<Test> result = RunDetachedCriteria(crit);
  if (result.Count == 0)
    break;
  Test obj = result[0];
  // ... work ...
  EvictObject(obj);
  i++;
}

But it looks somewhat inefficient to me, unless your objects are really huge.