WIP - Improve select clause transformation for Linq provider

src/NHibernate.DomainModel/Northwind/Entities/Animal.cs

@@ -12,7 +12,8 @@ public class Animal
         public virtual Animal Father { get; set; }
         public virtual IList<Animal> Children { get; set; }
         public virtual string SerialNumber { get; set; }
-
+		public virtual string FatherSerialNumber => Father?.SerialNumber;
+		public virtual bool HasFather => Father != null;
 		public virtual Animal FatherOrMother => Father ?? Mother;
 	}
 

src/NHibernate.DomainModel/Northwind/Entities/DynamicUser.cs

@@ -0,0 +1,18 @@
+using System.Collections;
+
+namespace NHibernate.DomainModel.Northwind.Entities
+{
+	public class DynamicUser : IEnumerable
+	{
+		public virtual int Id { get; set; }
+
+		public virtual dynamic Properties { get; set; }
+
+		public virtual IDictionary Settings { get; set; }
+
+		public virtual IEnumerator GetEnumerator()
+		{
+			throw new System.NotImplementedException();
+		}
+	}
+}

src/NHibernate.DomainModel/Northwind/Entities/Northwind.cs

@@ -69,6 +69,11 @@ public IQueryable<User> Users
             get { return _session.Query<User>(); }
         }
 
+        public IQueryable<DynamicUser> DynamicUsers
+        {
+            get { return _session.Query<DynamicUser>(); }
+        }
+
         public IQueryable<PatientRecord> PatientRecords
         {
             get { return _session.Query<PatientRecord>(); }

src/NHibernate.DomainModel/Northwind/Entities/Role.cs

@@ -7,5 +7,6 @@ public class Role
 		public virtual bool IsActive { get; set; }
 		public virtual AnotherEntity Entity { get; set; }
 		public virtual Role ParentRole { get; set; }
+		public virtual User CreatedBy { get; set; } // Not mapped
 	}
 }

src/NHibernate.DomainModel/Northwind/Entities/User.cs

@@ -48,10 +48,16 @@ public class User : IUser, IEntity
 
         public virtual FeatureSet Features { get; set; }
 
+		public virtual User NotMappedUser => this;
+
 		public virtual EnumStoredAsString Enum1 { get; set; }
 
+		public virtual EnumStoredAsString? NullableEnum1 { get; set; }
+
 		public virtual EnumStoredAsInt32 Enum2 { get; set; }
 
+		public virtual EnumStoredAsInt32? NullableEnum2 { get; set; }
+
 		public virtual IUser CreatedBy { get; set; }
 
 		public virtual IUser ModifiedBy { get; set; }

src/NHibernate.DomainModel/Northwind/Entities/UserComponent.cs

@@ -5,10 +5,14 @@ public class UserComponent
         public string Property1 { get; set; }
         public string Property2 { get; set; }
         public UserComponent2 OtherComponent { get; set; }
+
+		public string Property3 => $"{Property1}{Property2}";
     }
 
     public class UserComponent2
     {
         public string OtherProperty1 { get; set; }
+
+		public string OtherProperty2 => OtherProperty1;
     }
-}
+}

src/NHibernate.DomainModel/Northwind/Entities/UserDto.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace NHibernate.DomainModel.Northwind.Entities
 {
@@ -9,11 +10,13 @@ public class UserDto
 		public virtual int InvalidLoginAttempts { get; set; }
 		public virtual string RoleName { get; set; }
 		public virtual UserDto2 Dto2 { get; set; }
+		public virtual List<UserDto2> Dto2List { get; set; } = new List<UserDto2>();
 
 		public UserDto(int id, string name)
 		{
 			Id = id;
 			Name = name;
+			Dto2 = new UserDto2();
 		}
 	}
 

src/NHibernate.DomainModel/Northwind/Mappings/DynamicUser.hbm.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="NHibernate.DomainModel.Northwind.Entities" assembly="NHibernate.DomainModel">
+  <class name="DynamicUser" mutable="false">
+    <subselect>
+      select * from Users
+    </subselect>
+
+    <id name="Id" column="UserId" type="Int32">
+      <generator class="assigned" />
+    </id>
+
+    <dynamic-component name="Properties">
+      <property name="Name" type="AnsiString" />
+      <property name="Enum1" type="NHibernate.DomainModel.Northwind.Entities.EnumStoredAsStringType, NHibernate.DomainModel">
+        <column name="Enum1" length="12" />
+      </property>
+      <many-to-one name="CreatedBy" class="User" not-null="true" lazy="false">
+        <column name="CreatedById" not-null="true" />
+      </many-to-one>
+    </dynamic-component>
+
+    <dynamic-component name="Settings">
+      <property name="Property1" type="AnsiString" />
+      <property name="Property2" type="AnsiString" />
+      <many-to-one name="ModifiedBy" class="User" lazy="false">
+        <column name="ModifiedById" />
+      </many-to-one>
+    </dynamic-component>
+  </class>
+</hibernate-mapping>

src/NHibernate.DomainModel/Northwind/Mappings/User.hbm.xml

@@ -24,8 +24,14 @@
       <column name="Enum1" length="12" />
     </property>
 
+    <property name="NullableEnum1" type="NHibernate.DomainModel.Northwind.Entities.EnumStoredAsStringType, NHibernate.DomainModel"
+              formula="(case when Enum1 = 'Unspecified' then null else Enum1 end)" insert="false" update="false">
+    </property>
+
     <property name="Enum2" not-null="true" />
 
+    <property name="NullableEnum2" formula="(case when Enum2 = 0 then null else Enum2 end)" insert="false" update="false" />
+
     <property name="Features" not-null="true" />
 
     <many-to-one name="Role" class="Role">

src/NHibernate.Test/Async/Linq/EnumTests.cs

@@ -61,5 +61,42 @@ public async Task CanQueryOnEnumStoredAsString_Small_1Async()
 
 			Assert.AreEqual(expectedCount, query.Count);
 		}
+
+		[Test]
+		public async Task ConditionalNavigationPropertyAsync()
+		{
+			EnumStoredAsString? type = null;
+			await (db.Users.Where(o => o.Enum1 == EnumStoredAsString.Large).ToListAsync());
+			await (db.Users.Where(o => EnumStoredAsString.Large != o.Enum1).ToListAsync());
+			await (db.Users.Where(o => (o.NullableEnum1 ?? EnumStoredAsString.Large) == EnumStoredAsString.Medium).ToListAsync());
+			await (db.Users.Where(o => ((o.NullableEnum1 ?? type) ?? o.Enum1) == EnumStoredAsString.Medium).ToListAsync());
+
+			await (db.Users.Where(o => (o.NullableEnum1.HasValue ? o.Enum1 : EnumStoredAsString.Unspecified) == EnumStoredAsString.Medium).ToListAsync());
+			await (db.Users.Where(o => (o.Enum1 != EnumStoredAsString.Large
+				                    ? (o.NullableEnum1.HasValue ? o.Enum1 : EnumStoredAsString.Unspecified)
+				                    : EnumStoredAsString.Small) == EnumStoredAsString.Medium).ToListAsync());
+
+			await (db.Users.Where(o => (o.Enum1 == EnumStoredAsString.Large ? o.Role : o.Role).Name == "test").ToListAsync());
+		}
+
+		[Test]
+		public async Task CanQueryComplexExpressionOnEnumStoredAsStringAsync()
+		{
+			var type = EnumStoredAsString.Unspecified;
+			var query = await ((from user in db.Users
+			             where (user.NullableEnum1 == EnumStoredAsString.Large
+				                   ? EnumStoredAsString.Medium
+				                   : user.NullableEnum1 ?? user.Enum1
+			                   ) == type
+			             select new
+			             {
+				             user,
+				             simple = user.Enum1,
+				             condition = user.Enum1 == EnumStoredAsString.Large ? EnumStoredAsString.Medium : user.Enum1,
+				             coalesce = user.NullableEnum1 ?? EnumStoredAsString.Medium
+			             }).ToListAsync());
+
+			Assert.That(query.Count, Is.EqualTo(0));
+		}
 	}
 }

src/NHibernate.Test/Async/Linq/ParameterTests.cs

@@ -88,6 +88,34 @@ public async Task UsingTwoEntityParametersAsync()
 				2));
 		}
 
+		[Test]
+		public async Task UsingEntityEnumerableParameterTwiceAsync()
+		{
+			if (!Dialect.SupportsSubSelects)
+			{
+				Assert.Ignore();
+			}
+
+			var enumerable = await (db.DynamicUsers.FirstAsync());
+			await (AssertTotalParametersAsync(
+				db.DynamicUsers.Where(o => o == enumerable && o != enumerable),
+				1));
+		}
+
+		[Test]
+		public async Task UsingEntityEnumerableListParameterTwiceAsync()
+		{
+			if (!Dialect.SupportsSubSelects)
+			{
+				Assert.Ignore();
+			}
+
+			var enumerable = new[] {await (db.DynamicUsers.FirstAsync())};
+			await (AssertTotalParametersAsync(
+				db.DynamicUsers.Where(o => enumerable.Contains(o) && enumerable.Contains(o)),
+				1));
+		}
+
 		[Test]
 		public async Task UsingValueTypeParameterTwiceAsync()
 		{