Update TryGetEntityName method

Author: maca88

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

@@ -407,6 +407,18 @@ public async Task CanSelectConditionalSubQueryAsync()
 						  })
 						  .ToListAsync());
 			Assert.That(list3, Has.Count.GreaterThan(0));
+
+			var list4 = await (db.Orders
+						  .Select(o => new
+						  {
+							  Employee = db.Employees.Any(e => e.Superior != null)
+								  ? db.Employees
+									  .Where(e => e.Superior != null)
+									  .Select(e => e.Superior).FirstOrDefault()
+								  : o.Employee.Superior != null ? o.Employee.Superior : o.Employee
+						  })
+						  .ToListAsync());
+			Assert.That(list4, Has.Count.GreaterThan(0));
 		}
 
 		[Test, KnownBug("NH-3045")]

src/NHibernate.Test/Linq/SelectionTests.cs

@@ -436,6 +436,18 @@ public void CanSelectConditionalSubQuery()
 						  })
 						  .ToList();
 			Assert.That(list3, Has.Count.GreaterThan(0));
+
+			var list4 = db.Orders
+						  .Select(o => new
+						  {
+							  Employee = db.Employees.Any(e => e.Superior != null)
+								  ? db.Employees
+									  .Where(e => e.Superior != null)
+									  .Select(e => e.Superior).FirstOrDefault()
+								  : o.Employee.Superior != null ? o.Employee.Superior : o.Employee
+						  })
+						  .ToList();
+			Assert.That(list4, Has.Count.GreaterThan(0));
 		}
 
 		[Test, KnownBug("NH-3045")]

src/NHibernate/Linq/Visitors/SelectClauseNominator.cs

@@ -8,6 +8,7 @@
 using NHibernate.Persister.Entity;
 using NHibernate.Type;
 using Remotion.Linq.Clauses.Expressions;
+using NHibernate.Util;
 
 namespace NHibernate.Linq.Visitors
 {
@@ -172,7 +173,7 @@ private bool CanBeEvaluatedInHql(MemberExpression memberExpression)
 			}
 
 			// Check whether the member is mapped
-			var entityName = TryGetEntityName(memberExpression, out var memberPath);
+			var entityName = ExpressionsHelper.TryGetEntityName(_parameters.SessionFactory, memberExpression, out var memberPath);
 			if (entityName == null)
 			{
 				return false; // Not mapped
@@ -207,9 +208,9 @@ private bool CanBeEvaluatedInHql(BinaryExpression binaryExpression)
 			var canBeEvaluated = CanBeEvaluatedInHql(binaryExpression.Left) &
 			                     CanBeEvaluatedInHql(binaryExpression.Right);
 
-			// Subtract datetimes on the client side as its result varies when executed on the server side.
+			// Subtract datetimes on the client side as the result varies when executed on the server side.
 			// In Sql Server when using datetime2 subtract is not possbile.
-			// In Oracle a number is returned that represents the difference bewteen the two in days.
+			// In Oracle a number is returned that represents the difference between the two in days.
 			if (new[]
 			    {
 				    ExpressionType.Subtract,
@@ -317,41 +318,6 @@ private void VisitMemberBindings(IEnumerable<MemberBinding> bindings)
 			}
 		}
 
-		private string TryGetEntityName(MemberExpression memberExpression, out string memberPath)
-		{
-			System.Type entityType;
-			memberPath = memberExpression.Member.Name;
-			// When having components we need to go though them in order to find the entity
-			while (memberExpression.Expression is MemberExpression subMemberExpression)
-			{
-				// In some cases we can encounter a property representing the entity e.g. [_0].Customer.CustomerId
-				if (subMemberExpression.NodeType == ExpressionType.MemberAccess)
-				{
-					var entityName = _parameters.SessionFactory.TryGetGuessEntityName(memberExpression.Member.ReflectedType);
-					if (entityName != null)
-					{
-						return entityName;
-					}
-				}
-
-				memberPath = $"{subMemberExpression.Member.Name}.{memberPath}"; // Build a path that can be used to get the property form the entity metadata
-				memberExpression = subMemberExpression;
-			}
-
-			// Try to get the actual entity type from the query source if possbile as member can be declared
-			// in a base type
-			if (memberExpression.Expression is QuerySourceReferenceExpression querySourceReferenceExpression)
-			{
-				entityType = querySourceReferenceExpression.Type;
-			}
-			else
-			{
-				entityType = memberExpression.Member.ReflectedType;
-			}
-
-			return _parameters.SessionFactory.TryGetGuessEntityName(entityType);
-		}
-
 		private static bool ContainsAnyOfTypes(IEnumerable<Expression> expressions, params System.Type[] types)
 		{
 			return expressions.Any(o => types.Contains(o.Type));

src/NHibernate/Tuple/Entity/EntityMetamodel.cs

@@ -50,6 +50,7 @@ public class EntityMetamodel
 		private readonly CascadeStyle[] cascadeStyles;
 
 		private readonly Dictionary<string, int?> propertyIndexes = new Dictionary<string, int?>();
+		private readonly IDictionary<string, IType> _identifierPropertyTypes = new Dictionary<string, IType>();
 		private readonly bool hasCollections;
 		private readonly bool hasMutableProperties;
 		private readonly bool hasLazyProperties;
@@ -428,6 +429,29 @@ private void MapPropertyToIndex(string path, Mapping.Property prop, int i)
 			}
 		}
 
+		private void MapIdentifierPropertyTypes(IdentifierProperty identifier)
+		{
+			MapIdentifierPropertyTypes(identifier.Name, identifier.Type);
+		}
+
+		private void MapIdentifierPropertyTypes(string path, IType propertyType)
+		{
+			if (!string.IsNullOrEmpty(path))
+			{
+				_identifierPropertyTypes[path] = propertyType;
+			}
+
+			if (propertyType is IAbstractComponentType componentType)
+			{
+				for (var i = 0; i < componentType.PropertyNames.Length; i++)
+				{
+					MapIdentifierPropertyTypes(
+						!string.IsNullOrEmpty(path) ? $"{path}.{componentType.PropertyNames[i]}" : componentType.PropertyNames[i],
+						componentType.Subtypes[i]);
+				}
+			}
+		}
+
 		public ISet<string> SubclassEntityNames
 		{
 			get { return subclassEntityNames; }
@@ -542,6 +566,11 @@ public int GetPropertyIndex(string propertyName)
 				return null;
 		}
 
+		internal IType GetIdentifierPropertyType(string memberPath)
+		{
+			return _identifierPropertyTypes.TryGetValue(memberPath, out var propertyType) ? propertyType : null;
+		}
+
 		public bool HasCollections
 		{
 			get { return hasCollections; }

src/NHibernate/Util/ExpressionsHelper.cs

@@ -1,6 +1,10 @@
 using System.Linq.Expressions;
 using System.Reflection;
 using System;
+using NHibernate.Engine;
+using NHibernate.Type;
+using Remotion.Linq.Clauses;
+using Remotion.Linq.Clauses.Expressions;
 
 namespace NHibernate.Util
 {
@@ -15,5 +19,64 @@ public static MemberInfo DecodeMemberAccessExpression<TEntity, TResult>(Expressi
 			}
 			return ((MemberExpression)expression.Body).Member;
 		}
+
+		internal static string TryGetEntityName(ISessionFactoryImplementor sessionFactory, MemberExpression memberExpression, out string memberPath)
+		{
+			string entityName;
+			memberPath = memberExpression.Member.Name;
+			// When having components we need to go though them in order to find the entity
+			while (memberExpression.Expression is MemberExpression subMemberExpression)
+			{
+				// In some cases we can encounter a property representing the entity e.g. [_0].Customer.CustomerId
+				if (subMemberExpression.NodeType == ExpressionType.MemberAccess)
+				{
+					entityName = sessionFactory.TryGetGuessEntityName(memberExpression.Member.ReflectedType);
+					if (entityName != null)
+					{
+						return entityName;
+					}
+				}
+
+				memberPath = $"{subMemberExpression.Member.Name}.{memberPath}"; // Build a path that can be used to get the property form the entity metadata
+				memberExpression = subMemberExpression;
+			}
+
+			// Try to get the actual entity type from the query source if possbile as member can be declared
+			// in a base type
+			if (memberExpression.Expression is QuerySourceReferenceExpression querySourceReferenceExpression)
+			{
+				entityName = sessionFactory.TryGetGuessEntityName(querySourceReferenceExpression.Type);
+				if (entityName != null ||
+					!(querySourceReferenceExpression.ReferencedQuerySource is IFromClause fromClause) ||
+					!(fromClause.FromExpression is MemberExpression subMemberExpression))
+				{
+					return entityName;
+				}
+
+				// When the member type is not the one that is mapped (e.g. interface) we have to find the first
+				// mapped entity and calculate the entity name from there
+				entityName = TryGetEntityName(sessionFactory, subMemberExpression, out var subMemberPath);
+				if (entityName == null)
+				{
+					return null;
+				}
+
+				var persister = sessionFactory.GetEntityPersister(entityName);
+				var index = persister.EntityMetamodel.GetPropertyIndexOrNull(subMemberPath);
+				IAssociationType associationType;
+				if (index.HasValue)
+				{
+					associationType = persister.PropertyTypes[index.Value] as IAssociationType;
+				}
+				else
+				{
+					associationType = persister.EntityMetamodel.GetIdentifierPropertyType(subMemberPath) as IAssociationType;
+				}
+
+				return associationType?.GetAssociatedEntityName(sessionFactory);
+			}
+
+			return sessionFactory.TryGetGuessEntityName(memberExpression.Member.ReflectedType);
+		}
 	}
-}
+}