NH-3450 - Nested projections of subcollections with subcollections

[nhibernate-bot]

Mattias Viberg created an issue — 19th April 2013, 10:15:19:

The below mimcs the behaviour of the WCF Data Service query:

http://services.odata.org/Northwind/Northwind.svc/Shippers?$expand=Orders/Order_Details

It gets all Shippers and expands Shipper.Orders and Order.Order_Details (called OrderLines below). However it generates sql with a stray '.' which throws upon exection.

[Test]
		public void ProjectNestedSubcollections()
		{
		    var query = from s in db.Shippers
		                select new ExpandedWrapper<Shipper, IEnumerable<ExpandedWrapper<Order, IEnumerable<OrderLine>>>>
		                    {

		                        ExpandedElement = s,
		                        Description = "Orders",
		                        ReferenceDescription = "",
		                        ProjectedProperty0 = s.Orders.Select(x => new ExpandedWrapper<Order, IEnumerable<OrderLine>>
		                            {
		                                ExpandedElement = x,
		                                Description = "OrderLines",
		                                ReferenceDescription = "",
		                                ProjectedProperty0 = x.OrderLines
		                            })

		                    };
			var result = query.ToList();
		}

I thought this was the same bug as NH-3417 but after some investigation it seems more closely related to the closed NH-3385 (both related to NH-3333 though). However I thought it deserved an own issue.

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Mattias Viberg added a comment — 25th April 2013, 11:22:16:

It seems that a subselect of a collection always generates a stray ".". If I remove the dot (with an interceptor), the query executes ok, but it failes to populate the OrderLines collection. I've provided a new test:

        [Test]
        public void ProjectNestedSubcollections2()
        {
            var query = from s in session.Query<Shipper>()
                        where s.ShipperId == 1
                        select new { Name = s.CompanyName, Orders = s.Orders.Select(o => new {o.OrderLines }) };
            var result = query.ToList();
            Assert.IsNotNull(result<0>.Orders.First().OrderLines);
        }

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Mattias Viberg added a comment — 26th April 2013, 8:34:44:

A week has passed since I created the issue, and still no feedback whatsoever.This bug is a showstopper in our project and I would hate it if we had to throw out Nhibernate because of it. I've tried solving it myself but no luck yet. As I understand it the support for nested selects is only one level deep?