#3628 - Don't join when linq comparison with composite id

Author: Jeff Hagen

src/NHibernate.DomainModel/NHibernate.DomainModel.csproj

@@ -15,4 +15,7 @@
   <ItemGroup>
     <ProjectReference Include="..\NHibernate\NHibernate.csproj" />
   </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Bcl.HashCode" Version="1.1.1" />
+  </ItemGroup>
 </Project>

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

@@ -5,5 +5,6 @@ public class AnotherEntity
         public virtual int Id { get; set; }
         public virtual string Output { get; set; }
 		public virtual string Input { get; set; }
+		public virtual CompositeIdEntity CompositeIdEntity { get; set; }
     }
-}
+}

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

@@ -0,0 +1,58 @@
+using System;
+
+namespace NHibernate.DomainModel.Northwind.Entities
+{
+	public class CompositeId : IComparable<CompositeId>
+	{
+		public int ObjectId { get; set; } 
+		public int TenantId { get; set; }
+
+		public CompositeId() { }
+		public CompositeId(int objectId, int tenantId)
+		{
+			ObjectId = objectId;
+			TenantId = tenantId;
+		}
+
+		public override string ToString() => ObjectId + "|" + TenantId;
+		protected bool Equals(CompositeId other) => ObjectId == other.ObjectId && TenantId == other.TenantId;
+		public static bool operator ==(CompositeId left, CompositeId right) => Equals(left, right);
+		public static bool operator !=(CompositeId left, CompositeId right) => !Equals(left, right);
+
+		public override bool Equals(object obj)
+		{
+			if (ReferenceEquals(null, obj) || obj.GetType() != this.GetType())
+			{
+				return false;
+			}
+			return ReferenceEquals(this, obj) || Equals((CompositeId)obj);
+		}
+
+		public override int GetHashCode() => HashCode.Combine(ObjectId, TenantId);
+
+		public int CompareTo(CompositeId other)
+		{
+			if (ReferenceEquals(this, other))
+			{
+				return 0;
+			}
+			else if (ReferenceEquals(other, null))
+			{
+				return 1;
+			}
+			
+			var idComparison = ObjectId.CompareTo(other.ObjectId);
+			if (idComparison != 0)
+			{
+				return idComparison;
+			}
+
+			return TenantId.CompareTo(other);
+		}
+	}
+    public class CompositeIdEntity
+    {
+        public virtual CompositeId Id { get; set; }
+        public virtual string Name { get; set; }
+    }
+}

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

@@ -113,5 +113,10 @@ public IQueryable<IUser> IUsers
         {
             get { return _session.Query<IUser>(); }
         }
+		
+		public IQueryable<AnotherEntity> AnotherEntity
+		{
+			get { return _session.Query<AnotherEntity>(); }
+		}
     }
 }

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

@@ -6,5 +6,9 @@
     </id>
     <property name="Output" />
     <property name="Input" />
+    <many-to-one name="CompositeIdEntity" fetch="select">
+      <column name="CompositeObjectId" />
+      <column name="CompositeTenantId" />
+    </many-to-one>
   </class>
 </hibernate-mapping>

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

@@ -0,0 +1,10 @@
+<?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="CompositeIdEntity" table="CompositeIdEntity">
+    <composite-id name="Id">
+      <key-property name="ObjectId" column="ObjectId" />
+      <key-property name="TenantId" column="TenantId" />
+    </composite-id>
+    <property name="Name" length="128" />
+  </class>
+</hibernate-mapping>

src/NHibernate.Test/CompositeId/CompositeIdFixture.cs

@@ -21,7 +21,7 @@ protected override string[] Mappings
 				return new string[]
 				       	{
 				       		"CompositeId.Customer.hbm.xml", "CompositeId.Order.hbm.xml", "CompositeId.LineItem.hbm.xml",
-				       		"CompositeId.Product.hbm.xml"
+				       		"CompositeId.Product.hbm.xml", "CompositeId.Shipper.hbm.xml"
 				       	};
 			}
 		}
@@ -64,9 +64,13 @@ public void CompositeIds()
 
 				Order o = new Order(c);
 				o.OrderDate = DateTime.Today;
+				o.Shipper = new Shipper() { Id = new NullableId(null, 13) };
+				s.Persist(o);
+				
 				LineItem li = new LineItem(o, p);
 				li.Quantity = 2;
-
+				s.Persist(li);
+				
 				t.Commit();
 			}
 
@@ -123,6 +127,19 @@ public void CompositeIds()
 				t.Commit();
 			}
 
+			using (s = OpenSession())
+			{
+				t = s.BeginTransaction();
+				var noShippersForWarehouse = s.Query<Order>()
+					// NOTE: .Where(x => x.Shipper.Id == new NullableId(null, 13)) improperly renders
+					// "where (ShipperId = @p1 and WarehouseId = @p2)" with @p1 = NULL (needs to be is null)
+					// But the effort to fix is pretty high due to how component tuples are managed in linq / hql.
+					.Where(x => x.Shipper.Id.WarehouseId == 13 && x.Shipper.Id.Id == null)
+					.ToList();
+				Assert.AreEqual(1, noShippersForWarehouse.Count);
+				t.Commit();
+			}
+
 			using (s = OpenSession())
 			{
 				t = s.BeginTransaction();
@@ -291,5 +308,14 @@ public void AnyOnCompositeId()
 				s.Query<Order>().Select(o => o.LineItems.Any()).ToList();
 			}
 		}
+
+		public void NullCompositeId()
+		{
+			using (var s = OpenSession())
+			{
+				s.Query<Order>().Where(o => o.LineItems.Any()).ToList();
+				s.Query<Order>().Select(o => o.LineItems.Any()).ToList();
+			}
+		}
 	}
 }

src/NHibernate.Test/CompositeId/NullableId.cs

@@ -0,0 +1,58 @@
+using System;
+
+namespace NHibernate.Test.CompositeId
+{
+	public class NullableId : IComparable<NullableId>
+	{
+		public int? Id { get; set; } 
+		public int WarehouseId { get; set; }
+
+		public NullableId() { }
+		public NullableId(int? id, int warehouseId)
+		{
+			Id = id;
+			WarehouseId = warehouseId;
+		}
+
+		public override string ToString() => Id + "|" + WarehouseId;
+		protected bool Equals(NullableId other) => Id == other.Id && WarehouseId == other.WarehouseId;
+		public static bool operator ==(NullableId left, NullableId right) => Equals(left, right);
+		public static bool operator !=(NullableId left, NullableId right) => !Equals(left, right);
+
+		public override bool Equals(object obj)
+		{
+			if (ReferenceEquals(null, obj) || obj.GetType() != this.GetType())
+			{
+				return false;
+			}
+
+			return ReferenceEquals(this, obj) || Equals((NullableId)obj);
+		}
+
+		public override int GetHashCode() => HashCode.Combine(Id, WarehouseId);
+
+		public int CompareTo(NullableId other)
+		{
+			if (ReferenceEquals(this, other))
+			{
+				return 0;
+			}
+			else if (ReferenceEquals(other, null) || !other.Id.HasValue)
+			{
+				return 1;
+			}
+			else if (!Id.HasValue)
+			{
+				return -1;
+			}
+
+			var idComparison = Id.Value.CompareTo(other.Id);
+			if (idComparison != 0)
+			{
+				return idComparison;
+			}
+
+			return WarehouseId.CompareTo(other.WarehouseId);
+		}
+	}
+}

src/NHibernate.Test/CompositeId/Order.cs

@@ -48,6 +48,7 @@ public override int GetHashCode()
 		private Customer customer;
 		private IList<LineItem> lineItems = new List<LineItem>();
 		private decimal total;
+		private Shipper shipper;
 
 		public Order() {}
 		public Order(Customer customer)
@@ -87,6 +88,12 @@ public virtual decimal Total
 			get { return total; }
 			set { total = value; }
 		}
+		
+		public virtual Shipper Shipper
+		{
+			get { return shipper; }
+			set { shipper = value; }
+		}
 
 		public virtual LineItem GenerateLineItem(Product product, int quantity)
 		{
@@ -96,4 +103,4 @@ public virtual LineItem GenerateLineItem(Product product, int quantity)
 			return li;
 		}
 	}
-}
+}

src/NHibernate.Test/CompositeId/Order.hbm.xml

@@ -43,6 +43,11 @@
     		insert="false"
 			update="false" 
 			not-null="true"/>
+
+      <many-to-one name="Shipper" fetch="select">
+        <column name="ShipperId" not-null="false"/>
+        <column name="WarehouseId" />
+      </many-to-one>
 
     	<bag name="LineItems"
     		fetch="join"