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nhibernatecoalescequeryover

NHibernate QueryOver order by first non-null value (coalescing)

What I'm trying to come up is something that's expressed like this:

var result = Session.QueryOver<Foo>().OrderBy(f => f.UpdatedAt ?? f.CreatedAt);

Sure enough, this doesn't work. Rough equivalent of this in T-SQL is

... order by coalesce(f.UpdatedAt, f.CreatedAt)

What's the kosher way to do "coalescing" in NHibernate QueryOver?

Solution 
  • .OrderBy(Projections.SqlFunction("coalesce",
                                 NHibernateUtil.DateTime,
                                 Projections.Property<Foo>(x => x.UpdatedAt),
                                 Projections.Property<Foo>(x => x.CreatedAt)))