More correct fix based on collection mapping information

Author: Dmitry Naumov

src/NHibernate.Test/NHSpecificTest/NH3408/Fixture.cs

@@ -12,8 +12,8 @@ public void ProjectAnonymousTypeWithArrayProperty()
 		{
 			using (var session = OpenSession())
 			{
-				var query = from p in session.Query<Person>()
-							select new { p.Photo };
+				var query = from c in session.Query<Country>()
+							select new { c.Picture, c.NationalHolidays };
 
 				var result = query.ToList();
 			}

src/NHibernate.Test/NHSpecificTest/NH3408/Mappings.hbm.xml

@@ -2,12 +2,18 @@
 <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
            namespace="NHibernate.Test.NHSpecificTest.NH3408"
            assembly="NHibernate.Test">
-  <class name="Person">
+  <class name="Country">
     <id name="Id">
       <generator class="increment"/>
     </id>
     <property name="Name"/>
-    <property name="Photo"/>
+    <property name="Picture"/>
+    <set name="NationalHolidays" table="Holiday">
+      <key column="CalendarID" />
+      <element type="System.DateTime">
+        <column name="Holiday" sql-type="smalldatetime" />
+      </element>
+    </set>
   </class>
 
 </hibernate-mapping>

src/NHibernate.Test/NHSpecificTest/NH3408/Model.cs

@@ -1,11 +1,15 @@
 namespace NHibernate.Test.NHSpecificTest.NH3408
 {
-	public class Person
+	using System;
+
+	public class Country
 	{
 		public virtual int Id { get; set; }
 
 		public virtual string Name { get; set; }
 
-		public virtual byte[] Photo { get; set; }
+		public virtual byte[] Picture { get; set; }
+
+		public virtual DateTime[] NationalHolidays { get; set; }
 	}
 }

src/NHibernate/Linq/NestedSelects/NestedSelectDetector.cs

@@ -5,9 +5,18 @@
 
 namespace NHibernate.Linq.NestedSelects
 {
+	using System.Reflection;
+	using NHibernate.Metadata;
+
 	internal class NestedSelectDetector : NhExpressionTreeVisitor
 	{
 		private readonly ICollection<Expression> _expressions = new List<Expression>();
+		private readonly IDictionary<string, ICollectionMetadata> _collectionMetadata;
+
+		public NestedSelectDetector(IDictionary<string, ICollectionMetadata> collectionMetadata)
+		{
+			_collectionMetadata = collectionMetadata;
+		}
 
 		public ICollection<Expression> Expressions
 		{
@@ -33,13 +42,20 @@ protected override Expression VisitMemberExpression(MemberExpression expression)
 			{
 				var memberType = expression.Member.GetPropertyOrFieldType();
 
-				if (memberType != null && memberType.IsCollectionType())
+				if (memberType != null && memberType.IsCollectionType() && IsMappedCollection(expression.Member))
 				{
 					Expressions.Add(expression);
 				}
 			}
 
 			return base.VisitMemberExpression(expression);
 		}
+
+		private bool IsMappedCollection(MemberInfo memberInfo)
+		{
+			var key = memberInfo.DeclaringType.FullName + "." + memberInfo.Name;
+
+			return _collectionMetadata.ContainsKey(key);
+		}
 	}
 }

src/NHibernate/Linq/NestedSelects/NestedSelectRewriter.cs

@@ -19,7 +19,7 @@ internal static class NestedSelectRewriter
 
 		public static void ReWrite(QueryModel queryModel, ISessionFactory sessionFactory)
 		{
-			var nsqmv = new NestedSelectDetector();
+			var nsqmv = new NestedSelectDetector(sessionFactory.GetAllCollectionMetadata());
 			nsqmv.VisitExpression(queryModel.SelectClause.Selector);
 			if (!nsqmv.HasSubqueries)
 				return;
@@ -113,7 +113,7 @@ private static Expression ProcessSubquery(ISessionFactory sessionFactory, IColle
 		private static Expression ProcessMemberExpression(ISessionFactory sessionFactory, ICollection<ExpressionHolder> elementExpression, QueryModel queryModel, Expression @group, Expression memberExpression)
 		{
 			var join = new NhJoinClause(new NameGenerator(queryModel).GetNewName(),
-													memberExpression.Type.GetGenericArguments()[0],
+													GetElementType((MemberExpression) memberExpression),
 													memberExpression);
 
 			queryModel.BodyClauses.Add(@join);
@@ -161,8 +161,18 @@ private static Expression SubCollectionQuery(System.Type collectionType, System.
 										 Expression.Call(whereMethod, source, predicate),
 										 selector);
 
+			if (collectionType.IsArray)
+			{
+				var toArrayMethod = EnumerableHelper.GetMethod("ToArray",
+															  new[] { typeof(IEnumerable<>) },
+															  new[] { elementType });
+
+				var array = Expression.Call(toArrayMethod, @select);
+				return array;
+			}
+
 			var toListMethod = EnumerableHelper.GetMethod("ToList",
-														  new[] { typeof (IEnumerable<>) },
+														  new[] { typeof(IEnumerable<>) },
 														  new[] { elementType });
 
 			var list = Expression.Call(toListMethod, @select);
@@ -237,5 +247,26 @@ private static Expression ConvertToObject(Expression expression)
 		{
 			return Expression.Convert(expression, typeof(object));
 		}
+
+		private static System.Type GetElementType(MemberExpression expression)
+		{
+			var type = expression.Type;
+			if (!type.IsCollectionType())
+			{
+				throw new ArgumentException();
+			}
+
+			if (type.IsGenericType)
+			{
+				return type.GetGenericArguments()[0];
+			}
+
+			if (type.IsArray)
+			{
+				return type.GetElementType();
+			}
+
+			throw new NotSupportedException("Unknown collection type " + type.FullName);
+		}
 	}
 }