NHibernate QueryOver Subquery

Question

I\'ve looked at the similar questions, but can\'t find a simple explanation. I could have missed it, but I promise I looked. Actually I can\'t even find the documentation ot

Answer 1

You need to create a dettached query containing the Id's and then use this sub query with the main query.

I have pasted an example here so you will need to replace the relevant bits with your class names etc.

First the set up (you can ignore this bit):-

public class TestDto {
  public long Id { get; set; }
  public string Name { get; set; }
}
...
TestDto dto = null;
var ids = new List { 1,2,5,7 };

Now the dettached query:-

var idSubQuery = QueryOver.Of()
  .WhereRestrictionOn(w => w.Id).IsIn(ids)
  .Select(Projections.Distinct(Projections.Property(s => s.Id)));

And the final bit is to put it all together:-

var query = Session.QueryOver()
    .JoinQueryOver(l => l.CmsRegionContentList)
    .WithSubquery
    .WhereProperty(m => m.Id)
    .In(idSubQuery)
    .SelectList(list => list
                            .Select(p => p.Id).WithAlias(() => dto.Id)
                            .Select(p => p.PageName).WithAlias(() => dto.Name)
                )
                .TransformUsing(Transformers.AliasToBean(typeof(TestDto)));

var model = query.List();

This will create the following SQL:-

SELECT
     this_.Id as y0_,
     this_.PageName as y1_ 
FROM cmspage this_ inner join cmsregioncontent cmsregionc1_ 
  on this_.Id=cmsregionc1_.PageId 
WHERE cmsregionc1_.Id in (
    SELECT
         distinct this_0_.Id as y0_ 
    FROM cmsregioncontent this_0_ 
    WHERE this_0_.Id in (
        1 /* ?p0 */,
         2 /* ?p1 */,
         5 /* ?p2 */,
         7 /* ?p3 */)
    )

Hopefully you will be able to follow this with your class/property names.