Refactoring fix #903 and fix #943

src/Mapster.Tests/WhenCtorNullableParamMapping.cs

@@ -1,5 +1,6 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Shouldly;
+using System.Collections.Generic;
 
 namespace Mapster.Tests
 {
@@ -60,6 +61,27 @@ public void Dto_To_Domain_AbstractClassNull_MapsCorrectly()
         }
 
 
+        /// <summary>
+        /// https://github.com/MapsterMapper/Mapster/issues/943
+        /// </summary>
+        [TestMethod]
+        public void NullableCtorPropagationCurrentWorkWithDestinationTransform()
+        {
+            var config = new TypeAdapterConfig();
+
+            config.Default
+                .AddDestinationTransform(DestinationTransform.EmptyCollectionIfNull);
+
+            // Arrange
+            var fooDto = new FooDto943();
+
+            // Act
+            var foo = fooDto.Adapt<Foo943>(config);
+
+            // Assert
+            foo.Strings.ShouldNotBeNull();
+        }
+
         #region Immutable classes with private setters, map via ctors
         private abstract class AbstractDomainTestClass
         {
@@ -96,6 +118,13 @@ public DomainTestClass(
         #endregion
 
         #region DTO classes
+
+        class FooDto943
+        {
+            public string[] Strings { get; set; }
+        }
+
+        record Foo943(List<string> Strings);
         private abstract class AbstractDtoTestClass
         {
             public string AbstractProperty { get; set; }

src/Mapster/Adapters/BaseAdapter.cs

@@ -448,7 +448,7 @@ protected virtual Expression CreateInstantiationExpression(Expression source, Ex
             }
         }
 
-        private static Expression CreateAdaptExpressionCore(Expression source, Type destinationType, CompileArgument arg, MemberMapping? mapping = null, Expression? destination = null)
+        internal static Expression CreateAdaptExpressionCore(Expression source, Type destinationType, CompileArgument arg, MemberMapping? mapping = null, Expression? destination = null)
         {
             var mapType = arg.MapType == MapType.MapToTarget && destination == null ? MapType.Map :
                 mapping?.UseDestinationValue == true ? MapType.MapToTarget :
@@ -501,10 +501,24 @@ internal Expression CreateAdaptExpression(Expression source, Type destinationTyp
 
             //adapt(_source);
             var notUsingDestinationValue = mapping is not { UseDestinationValue: true };
-           var exp = _source.Type == destinationType && arg.Settings.ShallowCopyForSameType == true && notUsingDestinationValue 
-                     && rule == null
-                ? _source
-                : CreateAdaptExpressionCore(_source, destinationType, arg, mapping, destination);
+            Expression exp;
+
+            if (_source.Type == destinationType && arg.Settings.ShallowCopyForSameType == true
+                && notUsingDestinationValue && rule == null)
+                exp = _source;
+            else if (source is ConditionalExpression cond && mapping != null)
+            {
+                // convert ApplyNullable Propagation for NotPrimitive Nullable types
+                if (mapping.Getter.Type.IsNotPrimitiveNullableType() && !mapping.DestinationMember.Type.IsNullable())
+                {
+                    var adapt = CreateAdaptExpressionCore(cond.IfTrue.GetNotPrimitiveNullableValue(), mapping.DestinationMember.Type, arg, mapping);
+                    exp = Expression.Condition(cond.Test, adapt, mapping.DestinationMember.Type.CreateDefault());
+                }
+                else
+                    exp = CreateAdaptExpressionCore(_source, destinationType, arg, mapping, destination);
+            }
+            else
+                exp = CreateAdaptExpressionCore(_source, destinationType, arg, mapping, destination);
 
             //transform(adapt(_source));
             if (notUsingDestinationValue)

src/Mapster/Adapters/BaseClassAdapter.cs

@@ -15,7 +15,7 @@
 
         #region Build the Adapter Model
 
         protected ClassMapping CreateClassConverter(Expression source, ClassModel classModel, CompileArgument arg, Expression? destination = null, bool ctorMapping = false, ClassModel recordRestorMemberModel = null)
         {
             var destinationMembers = classModel.Members;
             var unmappedDestinationMembers = new List<string>();
@@ -213,7 +213,7 @@
                    && ignore.Condition == null;
         }
 
         protected Expression CreateInstantiationExpression(Expression source, ClassMapping classConverter, CompileArgument arg, Expression? destination, ClassModel recordRestorParamModel = null)
         {
             var members = classConverter.Members;
 
@@ -247,7 +247,7 @@
                     }
                     else
                        getter = member.Getter
-                            .ApplyNullPropagationFromCtor(CreateAdaptExpression(member.Getter, member.DestinationMember.Type, arg, member), arg);
+                            .ApplyNullPropagationFromCtor(CreateAdaptExpressionCore(member.Getter, member.DestinationMember.Type, arg, member), arg);
 
 
                     if (member.Ignore.Condition != null)

src/Mapster/Adapters/ClassAdapter.cs

@@ -114,17 +114,7 @@ protected override Expression CreateBlockExpression(Expression source, Expressio
                     ? member.DestinationMember.GetExpression(destination)
                     : null;
 
-                Expression adapt;
-
-                // convert ApplyNullable Propagation for NotPrimitive Nullable types
-                if (member.Getter is ConditionalExpression cond && member.Getter.Type.IsNotPrimitiveNullableType()
-                    && !member.DestinationMember.Type.IsNullable())
-                {
-                    var value = CreateAdaptExpression(cond.IfTrue.GetNotPrimitiveNullableValue(), member.DestinationMember.Type, arg, member, destMember);
-                   adapt = Expression.Condition(cond.Test, value, member.DestinationMember.Type.CreateDefault());
-                }
-                else
-                    adapt = CreateAdaptExpression(member.Getter, member.DestinationMember.Type, arg, member, destMember);
+                var adapt = CreateAdaptExpression(member.Getter, member.DestinationMember.Type, arg, member, destMember);
 
                 if (member.UseDestinationValue
                     && member.DestinationMember.Type.IsMapsterImmutable()
@@ -262,17 +252,7 @@ private static Expression SetValueByReflection(MemberMapping member, MemberExpre
                 if (member.DestinationMember.SetterModifier == AccessModifier.None)
                     continue;
 
-                Expression value;
-
-                // convert ApplyNullable Propagation for NotPrimitive Nullable types
-                if (member.Getter is ConditionalExpression cond && member.Getter.Type.IsNotPrimitiveNullableType() 
-                    && !member.DestinationMember.Type.IsNullable())
-                {
-                    var adapt = CreateAdaptExpression(cond.IfTrue.GetNotPrimitiveNullableValue(), member.DestinationMember.Type, arg, member);
-                    value = Expression.Condition(cond.Test, adapt, member.DestinationMember.Type.CreateDefault());
-                }
-                else
-                    value = CreateAdaptExpression(member.Getter, member.DestinationMember.Type, arg, member);
+                var value = CreateAdaptExpression(member.Getter, member.DestinationMember.Type, arg, member);
 
                 //special null property check for projection
                 //if we don't set null to property, EF will create empty object

src/Mapster/Utils/ExpressionEx.cs

@@ -483,7 +483,12 @@ public static Expression ApplyNullPropagationFromCtor(this Expression getter, Ex
             if (condition == null)
                 return adapt;
 
-            return Expression.Condition(condition, adapt, adapt.Type.CreateDefault());
+            // add supporting DestinationTransforms
+            var transform = arg.Settings.DestinationTransforms.Find(it => it.Condition(adapt.Type));
+            if (transform != null)
+                return transform.TransformFunc(adapt.Type).Apply(arg.MapType, Expression.Condition(condition, adapt, Expression.Default(adapt.Type)));
+
+            return Expression.Condition(condition, adapt, Expression.Default(adapt.Type));
         }
 
         public static string? GetMemberPath(this LambdaExpression lambda, bool firstLevelOnly = false, bool noError = false)