Avoid double param type guessing and better NULL parameter handling

Author: bahusoid

src/NHibernate/IQuery.cs

@@ -6,6 +6,19 @@
 
 namespace NHibernate
 {
+	// 6.0 TODO add to IQuery
+	internal interface IQueryNextVer : IQuery
+	{
+		/// <summary>
+		/// Bind a value to a named query parameter
+		/// </summary>
+		/// <param name="name">The name of the parameter</param>
+		/// <param name="val">The possibly null parameter value</param>
+		/// <param name="type">The NHibernate <see cref="IType"/>.</param>
+		/// <param name="preferMetadataType">If true supplied type is used only if parameter metadata is missing</param>
+		IQuery SetParameter(string name, object val, IType type, bool preferMetadataType);
+	}
+
 	/// <summary>
 	/// An object-oriented representation of a NHibernate query.
 	/// </summary>

src/NHibernate/Impl/AbstractQueryImpl.cs

@@ -19,7 +19,7 @@ namespace NHibernate.Impl
 	/// <summary>
 	/// Abstract implementation of the IQuery interface.
 	/// </summary>
-	public abstract partial class AbstractQueryImpl : IQuery
+	public abstract partial class AbstractQueryImpl : IQuery, IQueryNextVer
 	{
 		private readonly string queryString;
 		protected readonly ISessionImplementor session;
@@ -242,17 +242,33 @@ public IQuery SetParameter(int position, object val, IType type)
 
 		public IQuery SetParameter(string name, object val, IType type)
 		{
-			if (!parameterMetadata.NamedParameterNames.Contains(name))
-			{
-				if (shouldIgnoredUnknownNamedParameters)//just ignore it
-					return this;
-				throw new ArgumentException("Parameter " + name + " does not exist as a named parameter in [" + QueryString + "]");
-			}
-			else
-			{
-				namedParameters[name] = new TypedValue(type, val, false);
+			return SetParameter(name, val, type, false);
+		}
+
+		//TODO 6.0: Add to IQuery interface
+		public IQuery SetParameter(string name, object val, IType type, bool preferMetadataType)
+		{
+			if (CheckParameterIgnored(name))
 				return this;
+
+			if (type == null || preferMetadataType)
+			{
+				type = parameterMetadata.GetNamedParameterExpectedType(name) ?? type ?? ParameterHelper.GuessType(val, session.Factory);
 			}
+
+			namedParameters[name] = new TypedValue(type, val, false);
+			return this;
+		}
+
+		private bool CheckParameterIgnored(string name)
+		{
+			if (parameterMetadata.NamedParameterNames.Contains(name))
+				return false;
+
+			if (shouldIgnoredUnknownNamedParameters) //just ignore it
+				return true;
+
+			throw new ArgumentException("Parameter " + name + " does not exist as a named parameter in [" + QueryString + "]");
 		}
 
 		public IQuery SetParameter<T>(int position, T val)
@@ -289,29 +305,7 @@ public IQuery SetParameter<T>(string name, T val)
 
 		public IQuery SetParameter(string name, object val)
 		{
-			if (!parameterMetadata.NamedParameterNames.Contains(name))
-			{
-				if (shouldIgnoredUnknownNamedParameters)//just ignore it
-					return this;
-			}
-
-			if (val == null)
-			{
-				IType type = parameterMetadata.GetNamedParameterExpectedType(name);
-				if (type == null)
-				{
-					throw new ArgumentNullException("val",
-																					"A type specific Set(name, val) should be called because the Type can not be guessed from a null value.");
-				}
-
-				SetParameter(name, val, type);
-			}
-			else
-			{
-				SetParameter(name, val, DetermineType(name, val));
-			}
-
-			return this;
+			return SetParameter(name, val, null, true);
 		}
 
 		public IQuery SetParameter(int position, object val)

src/NHibernate/Linq/DefaultQueryProvider.cs

@@ -253,8 +253,14 @@ protected virtual object ExecuteQuery(NhLinqExpression nhLinqExpression, IQuery
 #pragma warning restore 618
 		}
 
+		//TODO 6.0: Remove
 		private static void SetParameters(IQuery query, IDictionary<string, NamedParameter> parameters)
 		{
+			if (query is IQueryNextVer impl)
+			{
+				SetParameters(impl, parameters);
+				return;
+			}
 			foreach (var parameterName in query.NamedParameters)
 			{
 				// The parameter type will be taken from the parameter metadata
@@ -274,6 +280,25 @@ private static void SetParameters(IQuery query, IDictionary<string, NamedParamet
 			}
 		}
 
+		//TODO 6.0: Replace with
+		//private static void SetParameters(IQuery query, IDictionary<string, NamedParameter> parameters)
+		private static void SetParameters(IQueryNextVer query, IDictionary<string, NamedParameter> parameters)
+		{
+			foreach (var parameterName in query.NamedParameters)
+			{
+				// The parameter type will be taken from the parameter metadata
+				var parameter = parameters[parameterName];
+				if (parameter.IsCollection)
+				{
+					query.SetParameterList(parameter.Name, (IEnumerable) parameter.Value);
+				}
+				else
+				{
+					query.SetParameter(parameter.Name, parameter.Value, parameter.Type, parameter.IsGuessedType);
+				}
+			}
+		}
+
 		public virtual void SetResultTransformerAndAdditionalCriteria(IQuery query, NhLinqExpression nhExpression, IDictionary<string, Tuple<object, IType>> parameters)
 		{
 			if (nhExpression.ExpressionToHqlTranslationResults != null)