Add Projections.Conditional for CASE expressions with multiple conditions (#2816)

Fixes #2804

Author: perahoky

src/NHibernate.Test/Async/Criteria/ConditionalProjectionTest.cs

@@ -0,0 +1,101 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by AsyncGenerator.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+
+using System;
+using System.Linq;
+using NHibernate.Criterion;
+using NUnit.Framework;
+
+namespace NHibernate.Test.Criteria
+{
+	using System.Threading.Tasks;
+	[TestFixture]
+	public class ConditionalProjectionTestAsync : TestCase
+	{
+		protected override string MappingsAssembly => "NHibernate.Test";
+
+		protected override string[] Mappings => new [] {"Criteria.Enrolment.hbm.xml"};
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.Save(new Student {StudentNumber = 6L, Name = "testa"});
+				session.Save(new Student {StudentNumber = 5L, Name = "testz"});
+				session.Save(new Student {StudentNumber = 4L, Name = "test1"});
+				session.Save(new Student {StudentNumber = 3L, Name = "test2"});
+				session.Save(new Student {StudentNumber = 2L, Name = "test998"});
+				session.Save(new Student {StudentNumber = 1L, Name = "test999"});
+				transaction.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = Sfi.OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.CreateQuery("delete from System.Object").ExecuteUpdate();
+				transaction.Commit();
+			}
+		}
+
+		protected override bool AppliesTo(Dialect.Dialect dialect)
+		{
+			return !TestDialect.HasBrokenTypeInferenceOnSelectedParameters;
+		}
+
+		[Test]
+		public async Task UsingMultiConditionalsAsync()
+		{
+			using (var session = OpenSession())
+			using (session.BeginTransaction())
+			{
+				// when Name = "testa" then 1 ...
+				var orderOfNames = new Tuple<string, string>[]
+				{
+					System.Tuple.Create("test1", "1"),
+					System.Tuple.Create("testz", "2"),
+					System.Tuple.Create("test2", "3"),
+					System.Tuple.Create("testa", "4")
+				};
+
+				var criterionProjections =
+					orderOfNames
+						.Select(
+							x => new ConditionalProjectionCase(
+								Restrictions.Eq(nameof(Student.Name), x.Item1),
+								Projections.Constant(x.Item2)))
+						.ToArray();
+
+				// ... else 99
+				var elseProjection = Projections.Constant("99");
+
+				var conditionalsProjection = Projections.Conditional(criterionProjections, elseProjection);
+
+				var order = Order.Asc(conditionalsProjection);
+
+				var criteria = session.CreateCriteria(typeof(Student)).AddOrder(order);
+
+				var actuals = await (criteria.ListAsync<Student>());
+
+				Assert.That(actuals.Count, Is.GreaterThanOrEqualTo(orderOfNames.Length));
+				for (var i = 0; i < orderOfNames.Length; i++)
+				{
+					var expected = orderOfNames[i];
+					var actual = actuals[i];
+
+					Assert.That(actual.Name, Is.EqualTo(expected.Item1));
+				}
+			}
+		}
+	}
+}

src/NHibernate.Test/Criteria/ConditionalProjectionTest.cs

@@ -0,0 +1,90 @@
+using System;
+using System.Linq;
+using NHibernate.Criterion;
+using NUnit.Framework;
+
+namespace NHibernate.Test.Criteria
+{
+	[TestFixture]
+	public class ConditionalProjectionTest : TestCase
+	{
+		protected override string MappingsAssembly => "NHibernate.Test";
+
+		protected override string[] Mappings => new [] {"Criteria.Enrolment.hbm.xml"};
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.Save(new Student {StudentNumber = 6L, Name = "testa"});
+				session.Save(new Student {StudentNumber = 5L, Name = "testz"});
+				session.Save(new Student {StudentNumber = 4L, Name = "test1"});
+				session.Save(new Student {StudentNumber = 3L, Name = "test2"});
+				session.Save(new Student {StudentNumber = 2L, Name = "test998"});
+				session.Save(new Student {StudentNumber = 1L, Name = "test999"});
+				transaction.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = Sfi.OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.CreateQuery("delete from System.Object").ExecuteUpdate();
+				transaction.Commit();
+			}
+		}
+
+		protected override bool AppliesTo(Dialect.Dialect dialect)
+		{
+			return !TestDialect.HasBrokenTypeInferenceOnSelectedParameters;
+		}
+
+		[Test]
+		public void UsingMultiConditionals()
+		{
+			using (var session = OpenSession())
+			using (session.BeginTransaction())
+			{
+				// when Name = "testa" then 1 ...
+				var orderOfNames = new Tuple<string, string>[]
+				{
+					System.Tuple.Create("test1", "1"),
+					System.Tuple.Create("testz", "2"),
+					System.Tuple.Create("test2", "3"),
+					System.Tuple.Create("testa", "4")
+				};
+
+				var criterionProjections =
+					orderOfNames
+						.Select(
+							x => new ConditionalProjectionCase(
+								Restrictions.Eq(nameof(Student.Name), x.Item1),
+								Projections.Constant(x.Item2)))
+						.ToArray();
+
+				// ... else 99
+				var elseProjection = Projections.Constant("99");
+
+				var conditionalsProjection = Projections.Conditional(criterionProjections, elseProjection);
+
+				var order = Order.Asc(conditionalsProjection);
+
+				var criteria = session.CreateCriteria(typeof(Student)).AddOrder(order);
+
+				var actuals = criteria.List<Student>();
+
+				Assert.That(actuals.Count, Is.GreaterThanOrEqualTo(orderOfNames.Length));
+				for (var i = 0; i < orderOfNames.Length; i++)
+				{
+					var expected = orderOfNames[i];
+					var actual = actuals[i];
+
+					Assert.That(actual.Name, Is.EqualTo(expected.Item1));
+				}
+			}
+		}
+	}
+}