I've been working on a WPF application which is maybe another post. The work is done and I have started localizing the applications. Localization was mostly chanding the FlowDirection and lables / texts for other languages, but when testing the application, I came across an intresting problem with Nhibernate. The application worked correctly in default (en-us) culture, but not in fa-ir, as NHibernate reported problems when running the working query. This highlights the problem:

[Test]
public void Can_Run_Query_In_Persian_Culture()
{
  using(new CultureContext(new PersianCultureInfo()))
  {
      using (UnitOfWork.Start())
      {
          var todayStart = new DateTime(DateTime.Today.Year, DateTime.Today.Month, DateTime.Today.Day, 0, 0, 0, CultureHelper.DefaultCalendar);
          var todayEnd = new DateTime(DateTime.Today.Year, DateTime.Today.Month, DateTime.Today.Day, 23, 59, 59, CultureHelper.DefaultCalendar);

          var queryable = UnitOfWork.CurrentSession.Linq<Purchase>();
          var query = from sales in queryable
                      where sales.PurchaseDate >= todayStart && sales.PurchaseDate <= todayEnd
                      select sales;

          Assert.DoesNotThrow(() => query.ToList());
      }
  }
}

The test which is totally working on other cultures, fails miserably in fa-ir. The reason is somewhere in the criteria parameter being converted to string. The output of the query being run on the database is this:

[SELECT this_.PurchaseId as PurchaseId4_0_, this_.PaidValue as PaidValue4_0_, this_.PurchaseDate as Purchase3_4_0_, this_.Quantity as Quantity4_0_, this_.IsOwed as IsOwed4_0_, this_.Product_id as Product6_4_0_, this_.PurchaseRegisteredBy_id as Purchase7_4_0_, this_.Purchaser_id as Purchaser8_4_0_ from `Purchase` this_ WHERE (this_.PurchaseDate >= ? and this_.PurchaseDate <= ?) ]

Positional parameters: #0>1388/02/30 12:00:00 ق.ظ #1>1388/02/30 11:59:59 ب.ظ

It is obvious that date values are converted to String using current Culture of the running thread, while the conversion should use invariant culture instead:

Invalid:

var dateValue = todayStart.ToString();

Valid:

var dateValue = todayStart.ToString(CultureInfo.InvariantCulture);

Any workaround for this? I haven't found any yet. In fact I still do not exactly know if this is NH core problem or the Linq extensions and since I'm running a build from the trunk, I'm not sure if this is reproducible on released versions.

Update : The problem was actually related to JET Driver of NHibernate Contrib project. A patch is created and sent to authorities.