Is it possible to create ICriteria/ICriterion from LINQ or HQL?

Question

I am creating a method that can create filter understood by NHibernate (by filter i mean a set of ICriteria object for example) from my abstract filter object.

public static IEnumerable<ICriterion> ToNhCriteria(this MyCriteria criteria)
{
   // T4 generated function
   // lots of result.Add(Expression.Or(Expression.Eq(),Expression.Eq)) expression trees - hard to generate
   // Is there a way to generate HQL/Linq query here istead?
}

then i want to do something like

session.CreateCriteria<Entity>().Add(myCriteria.ToNhCriteria())

to filter entities. The problem is that using Expression. methods (Expression.Or etc) is quite tedious (the method is generated and i have multiple or statements that have to be joined into an expression somehow). Is there a way to avoid using Expression.Or() and create ICrietrion / ICriteria using LINQ or HQL?

Are you using T4 at design time or runtime to generate ICriteria? If at design time, what is stopping you from using T4 to generate HQL (or Linq) instead? — Michael Maddox, Apr 27 '10 at 17:31
Yes I am using T4 in design time and as you suggested i could use HQL or Linq instead of ICriteria. The problem was caused by my lack of knowledge rather than by framework limitations. Currently I am using ICriteria API though as it seems to be most readable for someone reading T4 and it works properly now. — adrin, Apr 28 '10 at 07:16

score 1 · Answer 1 · edited May 23 '17 at 12:11

1

Hey, did you check out this question? It shows going from Linq to NHibernate to a MultiCriteria (and on the way transforms a linq query to an ICriteria)

edited May 23 '17 at 12:11

Community

1
1

answered Jun 21 '10 at 04:52

ZeroBugBounce

3,652
3
31
40

score 0 · Answer 2 · answered Apr 27 '10 at 15:22

0

No that is not possible. Why don't you use linq instead of criteria?

answered Apr 27 '10 at 15:22

Paco

8,335
3
30
41

score 0 · Answer 3 · answered Apr 27 '10 at 17:43

Linq is not the best solution unless you want to do filtering on collection-side not on datbase-side using WHERE clauses. Ayende suggests that ICriteria API is well suited for dynamic filter creation, the problem i had with multiple ORs has been tackled by using Restrictions.Disjunction()... that simplified a lot At the time I asked the question I just didn't realize such things exist in NHibernate :)

Is it possible to create ICriteria/ICriterion from LINQ or HQL?

3 Answers3