Add ability to set custom collection type as string in mapping by code

This allows to use TypeDefs that allow setting parameters for the collection.

Author: hazzik

src/NHibernate.Test/MappingByCode/MappersTests/IdBagMapperTest.cs

@@ -121,7 +121,7 @@ public void SetCollectionTypeByWrongTypeShouldThrow()
 		{
 			var hbm = new HbmIdbag();
 			var mapper = new IdBagMapper(typeof(Animal), typeof(Animal), hbm);
-			Assert.That(() => mapper.Type(null), Throws.TypeOf<ArgumentNullException>());
+			Assert.That(() => mapper.Type(default(System.Type)), Throws.TypeOf<ArgumentNullException>());
 			Assert.That(() => mapper.Type(typeof(object)), Throws.TypeOf<ArgumentOutOfRangeException>());
 		}
 

src/NHibernate.Test/UserCollection/Parameterized/ParameterizedUserCollectionTypeByCodeFixture.cs

@@ -0,0 +1,77 @@
+using NHibernate.Cfg;
+using NHibernate.Cfg.MappingSchema;
+using NHibernate.Mapping.ByCode;
+using NHibernate.Util;
+using NUnit.Framework;
+
+namespace NHibernate.Test.UserCollection.Parameterized
+{
+	public class ParameterizedUserCollectionTypeByCodeFixture : TestCaseMappingByCode
+	{
+		protected override string MappingsAssembly => "NHibernate.Test";
+
+		protected override void AddMappings(Configuration configuration)
+		{
+			configuration.TypeDefinition<DefaultableListType>(
+				c =>
+				{
+					c.Alias = "DefaultableList";
+					c.Properties = new {@default = "Hello"};
+				});
+
+			base.AddMappings(configuration);
+		}
+
+		protected override HbmMapping GetMappings()
+		{
+			var mapper = new ModelMapper();
+
+			mapper.Class<Entity>(
+				c =>
+				{
+					c.Id(e => e.Name, im => im.Access(Accessor.Field));
+					c.List(
+						e => e.Values,
+						lpm =>
+						{
+							lpm.Fetch(CollectionFetchMode.Join);
+							lpm.Table("ENT_VAL");
+							lpm.Type("DefaultableList");
+							lpm.Key(km => km.Column("ENT_ID"));
+							lpm.Index(lim => lim.Column("POS"));
+						},
+						lm =>
+						{
+							lm.Element(em => em.Column("VAL"));
+						});
+				});
+			
+			return mapper.CompileMappingForAllExplicitlyAddedEntities();
+		}
+
+		[Test]
+		public void BasicOperation()
+		{
+			using (var s = OpenSession())
+			using (var t = s.BeginTransaction())
+			{
+				var entity = new Entity("tester");
+				entity.Values.Add("value-1");
+				s.Persist(entity);
+				t.Commit();
+			}
+
+			using (var s = OpenSession())
+			using (var t = s.BeginTransaction())
+			{
+				var entity = s.Get<Entity>("tester");
+				Assert.That(NHibernateUtil.IsInitialized(entity.Values), Is.True);
+				Assert.That(entity.Values.Count, Is.EqualTo(1));
+				Assert.That(((IDefaultableList) entity.Values).DefaultValue, Is.EqualTo("Hello"));
+
+				s.Delete(entity);
+				t.Commit();
+			}
+		}
+	}
+}

src/NHibernate/Mapping/ByCode/ICollectionPropertiesMapper.cs

@@ -1,8 +1,11 @@
 using System;
 using System.Linq.Expressions;
 using System.Reflection;
+using NHibernate.Mapping.ByCode.Impl;
+using NHibernate.Mapping.ByCode.Impl.CustomizersImpl;
 using NHibernate.Persister.Collection;
 using NHibernate.UserTypes;
+using NHibernate.Util;
 
 namespace NHibernate.Mapping.ByCode
 {
@@ -54,4 +57,46 @@ public interface ICollectionPropertiesMapper<TEntity, TElement> : IEntityPropert
 		void Fetch(CollectionFetchMode fetchMode);
 		void Persister<TPersister>() where TPersister : ICollectionPersister;
 	}
+
+	public static class CollectionPropertiesMapperExtensions
+	{
+		//6.0 TODO: Merge into ICollectionPropertiesMapper<TEntity, TElement>
+		public static void Type<TEntity, TElement>(
+			this ICollectionPropertiesMapper<TEntity, TElement> mapper,
+			string collectionType)
+		{
+			ReflectHelper
+				.CastOrThrow<CollectionPropertiesCustomizer<TEntity, TElement>>(mapper, "Type(string)")
+				.Type(collectionType);
+		}
+
+		//6.0 TODO: Merge into ICollectionPropertiesMapper
+		public static void Type(
+			this ICollectionPropertiesMapper mapper,
+			string collectionType)
+		{
+			if (mapper == null) throw new ArgumentNullException(nameof(mapper));
+
+			switch (mapper)
+			{
+				case BagMapper bagMapper:
+					bagMapper.Type(collectionType);
+					break;
+				case IdBagMapper idBagMapper:
+					idBagMapper.Type(collectionType);
+					break;
+				case ListMapper listMapper:
+					listMapper.Type(collectionType);
+					break;
+				case MapMapper mapMapper:
+					mapMapper.Type(collectionType);
+					break;
+				case SetMapper setMapper:
+					setMapper.Type(collectionType);
+					break;
+				default:
+					throw new NotSupportedException($"{mapper.GetType().FullName} does not support Type(string)");
+			}
+		}
+	}
 }

src/NHibernate/Mapping/ByCode/Impl/BagMapper.cs

@@ -136,9 +136,15 @@ public void Type(System.Type collectionType)
 				                                      	"The collection type should be an implementation of IUserCollectionType.({0})",
 				                                      	collectionType));
 			}
+
 			mapping.collectiontype = collectionType.AssemblyQualifiedName;
 		}
 
+		public void Type(string collectionType)
+		{
+			mapping.collectiontype = collectionType ?? throw new ArgumentNullException(nameof(collectionType));
+		}
+
 		public void Table(string tableName)
 		{
 			mapping.table = tableName;

src/NHibernate/Mapping/ByCode/Impl/CustomizersImpl/CollectionPropertiesCustomizer.cs

@@ -88,6 +88,11 @@ public void Type(System.Type collectionType)
 			CustomizersHolder.AddCustomizer(PropertyPath, (ICollectionPropertiesMapper x) => x.Type(collectionType));
 		}
 
+		public void Type(string collectionType)
+		{
+			CustomizersHolder.AddCustomizer(PropertyPath, (ICollectionPropertiesMapper x) => x.Type(collectionType));
+		}
+
 		public void Table(string tableName)
 		{
 			CustomizersHolder.AddCustomizer(PropertyPath, (ICollectionPropertiesMapper x) => x.Table(tableName));

src/NHibernate/Mapping/ByCode/Impl/IdBagMapper.cs

@@ -145,6 +145,11 @@ public void Type(System.Type collectionType)
 			mapping.collectiontype = collectionType.AssemblyQualifiedName;
 		}
 
+		public void Type(string collectionType)
+		{
+			mapping.collectiontype = collectionType ?? throw new ArgumentNullException(nameof(collectionType));
+		}
+
 		public void Table(string tableName)
 		{
 			mapping.table = tableName;

src/NHibernate/Mapping/ByCode/Impl/ListMapper.cs

@@ -143,6 +143,11 @@ public void Type(System.Type collectionType)
 			mapping.collectiontype = collectionType.AssemblyQualifiedName;
 		}
 
+		public void Type(string collectionType)
+		{
+			mapping.collectiontype = collectionType ?? throw new ArgumentNullException(nameof(collectionType));
+		}
+
 		public void Table(string tableName)
 		{
 			mapping.table = tableName;

src/NHibernate/Mapping/ByCode/Impl/MapMapper.cs

@@ -160,6 +160,11 @@ public void Type(System.Type collectionType)
 			mapping.collectiontype = collectionType.AssemblyQualifiedName;
 		}
 
+		public void Type(string collectionType)
+		{
+			mapping.collectiontype = collectionType ?? throw new ArgumentNullException(nameof(collectionType));
+		}
+
 		public void Table(string tableName)
 		{
 			mapping.table = tableName;

src/NHibernate/Mapping/ByCode/Impl/SetMapper.cs

@@ -145,6 +145,11 @@ public void Type(System.Type collectionType)
 			mapping.collectiontype = collectionType.AssemblyQualifiedName;
 		}
 
+		public void Type(string collectionType)
+		{
+			mapping.collectiontype = collectionType ?? throw new ArgumentNullException(nameof(collectionType));
+		}
+
 		public void Table(string tableName)
 		{
 			mapping.table = tableName;