NHibernate ICriteria count the groups from group by clause

Question

I am trying to count the groups of query resulted from Group by clause, but I can't seem to get the count of each group using ICriteria.

My entity:

public class PageView
{

    #region public fields
    public virtual int PagelogID { get; set; }

    public virtual string PageTitle { get; set; }
    public virtual string UserID { get; set; }

    public virtual DateTime DateViewed{get;set;}  --->Map to Date_Viewed column
    public virtual string SessionID { get; set; }
    public virtual string UserGroup { get; set; }
    #endregion
}

I want to group the data by the year/month based on the DateViewed. Such result can be achieved by the following query:

select extract(year from DATE_VIEWED) "year", extract(month from DATE_VIEWED) "month", count(*) from PAGEVIEW_LOG where date_viewed > to_date(add_months(sysdate,-12)) 
group by extract(year from DATE_VIEWED), extract(month from DATE_VIEWED)
order by "year", "month" desc;

This is my Criteria:

        ProjectionList pl = Projections.ProjectionList();
        this.crit.Add(Expression.Gt("DateViewed", DateTime.Now.AddMonths(-12)));

        pl.Add(Projections.SqlGroupProjection(
            "Extract(month from Date_Viewed) MONTH",
            "Extract(month from Date_Viewed)",
            new String[] { "MONTH" },
            new NHibernate.Type.IType[] { NHibernateUtil.Int32 }), "MONTH");

        pl.Add(Projections.SqlGroupProjection(
            "Extract(year from Date_Viewed) YEAR",
            "Extract(year from Date_Viewed)",
            new String[] { "YEAR" },
            new NHibernate.Type.IType[] { NHibernateUtil.Int32 }), "YEAR");
        //pl.Add(Projections.Count("*"));
        this.crit.SetProjection(pl);
        this.crit.AddOrder(Order.Desc("YEAR"));
        this.crit.AddOrder(Order.Desc("MONTH"));

This successfully gives me everything I wanted besides the "Count(*)" part of the query.

What I have tried:

1: Add p1.Add(Projections.Count("YEAR"):

This gives me error as the Nhibernate doesn't recognize YEAR as a column despite I gave it an alias.

2: Add p1.Add(Projections.Count("*"):

Same result as above

3: Store the SqlGroupProjection for year column into a variable: IProjection yearProjection and add **p1.Add(Projections.Count(yearProjection) This gives me error for "length has to be greater than 0" error;

4: pl.Add(Projections.Count(Projections.RowCount())) No luck either

what am I missing here? How do I add Count(*) to the criteria?

Answer 1

I was very close:

Instead of doing: pl.Add(Projections.Count(Projections.RowCount()))

This should be: pl.Add(Projections.RowCount());