nHibernate count rows in subquery

Question

How can I do something like this in nHibernate:

select count(*)
from (subquery)

It is a rather simple query in SQL, but the solution is not so obvious in nHibernate. An obvious solution would be something along the line of:

    var rowcount = Session.QueryOver<Entity>()
       .Select(Projections.Alias(Projections.Count(Projections.SubQuery(detachedQuery)), "count"))
        .FutureValue<int>();

However, this results in an ArgumentOutOfRangeException:

Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

This SO answer doesn't work for me, as I have a more complex grouping. My question originates from an earlier question where I tried to use ToRowCountQuery, but that function strips groupings form the query.

VoodooChild · Accepted Answer · 2011-11-08 08:23:59Z

0

Once you have a session, you could

var criteria = session.CreateCriteria(....)

int count = (int) criteria.UniqueResult();

answered Nov 8, 2011 at 8:23

VoodooChild

9,8049 gold badges70 silver badges102 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

VoodooChild Over a year ago

See stackoverflow.com/questions/116188/… for more info. It is couple of years old, but hope it helps.

Pieter Over a year ago

Hmmm, I'm not sure how that would work. Where do I put my subquery? The related SO answer doesn't use a subquery, but just provides an alternative solution, which also works in that particular case. The Criteria-solution seems to be similar to my QueryOver solution which results in an exception. Next to that, I would prefer a solution using QueryOver.

Pieter · Accepted Answer · 2011-11-08 11:17:09Z

0

I found an old post by Ayende which gave me a solution (Counting paged data).

I created my own dialect as described in that post and added the rowcount function to my paged query. And presto, I got my rowcount in a single query to the database.

answered Nov 8, 2011 at 11:17

Pieter

3,3975 gold badges34 silver badges69 bronze badges

Collectives™ on Stack Overflow

nHibernate count rows in subquery

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related