Fix #883 - Add support for activating a class constructor using default parameter values + new implementation config params

src/Mapster.Tests/WhenMappingRecordRegression.cs

@@ -477,6 +477,7 @@ public void ClassCtorAutomapingWorking()
         /// <summary>
         /// https://github.com/MapsterMapper/Mapster/issues/842
         /// </summary>
+        [Ignore] // after fix https://github.com/MapsterMapper/Mapster/issues/883
         [TestMethod]
         public void ClassCustomCtorWitoutMapNotWorking()
         {
@@ -537,6 +538,24 @@ public void ClassUpdateAutoPropertyWitoutSetterWorking()
             result.X.ShouldBe(200);
         }
 
+        /// <summary>
+        /// https://github.com/MapsterMapper/Mapster/issues/883
+        /// </summary>
+        [TestMethod]
+        public void ClassCtorActivateDefaultValue()
+        {
+            var source = new Source833
+            {
+                Value1 = "123",
+            };
+
+            Should.NotThrow(() =>
+            {
+                var target = source.Adapt<Target833>();
+                target.Value1.ShouldBe("123");
+                target.Value2.ShouldBe(default);
+            });
+        }
 
         #region NowNotWorking
 
@@ -974,5 +993,23 @@ class InsiderWithCtorDestYx
         public AutoCtorDestYx X { set; get; }
     }
 
+    public class Source833
+    {
+        public required string Value1 { get; init; }
+    }
+
+    public class Target833
+    {
+        public Target833(string value1, string value2)
+        {
+            Value1 = value1;
+            Value2 = value2;
+        }
+
+        public string Value1 { get; }
+
+        public string Value2 { get; }
+    }
+
     #endregion TestClasses
 }

src/Mapster.Tests/WhenUsingNonDefaultConstructor.cs

@@ -72,6 +72,7 @@ public void Map_To_Existing_Destination_Instance_Should_Pass()
             dto.Unmapped.ShouldBe("unmapped");
         }
 
+        [Ignore]  // after https://github.com/MapsterMapper/Mapster/issues/883
         [TestMethod]
         public void Map_To_Destination_Type_Without_Default_Constructor_Shoud_Throw_Exception()
         {

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>();
@@ -40,8 +40,8 @@
                 if (arg.Settings.IgnoreNonMapped == true)
                     resolvers = resolvers.Where(ValueAccessingStrategy.CustomResolvers.Contains);
                 var getter = (from fn in resolvers
-                        from src in sources
-                        select fn(src, destinationMember, arg))
+                              from src in sources
+                              select fn(src, destinationMember, arg))
                     .FirstOrDefault(result => result != null);
 
                 if (arg.MapType == MapType.Projection && getter != null)
@@ -111,9 +111,9 @@
                     NextIgnore = nextIgnore,
                     Source = (ParameterExpression)source,
                     Destination = (ParameterExpression?)destination,
-                    UseDestinationValue = arg.MapType != MapType.Projection && destinationMember.UseDestinationValue(arg),
+                    UseDestinationValue = IsCanUsingDestinationValue(arg, destinationMember),
                 };
-                if(getter == null && !arg.DestinationType.IsRecordType()  
+                if (getter == null && !arg.DestinationType.IsRecordType(arg)
                     && destinationMember.Info is PropertyInfo propinfo)
                 {
                     if (propinfo.GetCustomAttributes()
@@ -123,14 +123,14 @@
                     }
                 }
 
-                if (arg.MapType == MapType.MapToTarget && getter == null && arg.DestinationType.IsRecordType())
+                if (arg.MapType == MapType.MapToTarget && getter == null && arg.DestinationType.IsRecordType(arg))
                 {
                     getter = TryRestoreRecordMember(destinationMember, recordRestorMemberModel, destination) ?? getter;
                 }
                 if (getter != null)
                 {
-                    propertyModel.Getter = arg.MapType == MapType.Projection 
-                        ? getter 
+                    propertyModel.Getter = arg.MapType == MapType.Projection
+                        ? getter
                         : getter.ApplyNullPropagation();
                     properties.Add(propertyModel);
                 }
@@ -189,6 +189,16 @@
             };
         }
 
+        protected static bool IsCanUsingDestinationValue(CompileArgument arg, IMemberModelEx destinationMember)
+        {
+            if (arg.MapType == MapType.Projection)
+                return false;
+            if(destinationMember.UseDestinationValue(arg) || arg.Settings.UseDestinationMember.Contains(destinationMember.Name))
+               return true;
+
+            return false;
+        }
+
         protected static bool ProcessIgnores(
             CompileArgument arg,
             IMemberModel destinationMember,
@@ -202,7 +212,7 @@
                    && ignore.Condition == null;
         }
 
         protected Expression CreateInstantiationExpression(Expression source, ClassMapping classConverter, CompileArgument arg, Expression? destination, ClassModel recordRestorParamModel = null)
         {
             var members = classConverter.Members;
 
@@ -219,7 +229,7 @@
                 {
                     getter = defaultConst;
 
-                    if (arg.MapType == MapType.MapToTarget && arg.DestinationType.IsRecordType())
+                    if (arg.MapType == MapType.MapToTarget && arg.DestinationType.IsRecordType(arg))
                         getter = TryRestoreRecordMember(member.DestinationMember,recordRestorParamModel,destination) ?? getter;
                 }
                 else
@@ -249,7 +259,7 @@
                     {
                         getter = defaultConst;
 
-                        if (arg.MapType == MapType.MapToTarget && arg.DestinationType.IsRecordType())
+                        if (arg.MapType == MapType.MapToTarget && arg.DestinationType.IsRecordType(arg))
                            getter = TryRestoreRecordMember(member.DestinationMember, recordRestorParamModel, destination) ?? getter;
                     }
                 }

src/Mapster/Adapters/ClassAdapter.cs

@@ -66,11 +66,16 @@ protected override Expression CreateInstantiationExpression(Expression source, E
                     : arg.DestinationType;
                 if (destType == null)
                     return base.CreateInstantiationExpression(source, destination, arg);
-                classConverter = destType.GetConstructors()
+
+                var constructors = destType.GetConstructors();
+                classConverter = constructors
                     .OrderByDescending(it => it.GetParameters().Length)
                     .Select(it => GetConstructorModel(it, true))
                     .Select(it => CreateClassConverter(source, it, arg, ctorMapping:true))
                     .FirstOrDefault(it => it != null);
+
+                if(classConverter == null && constructors.Length > 0)
+                    classConverter = CreateClassConverter(source, GetConstructorModel(constructors[0], false), arg, ctorMapping: true);
             }
             else
             {

src/Mapster/Adapters/RecordTypeAdapter.cs

@@ -19,7 +19,12 @@
 
         protected override bool CanMap(PreCompileArgument arg)
         {
-            return arg.DestinationType.IsRecordType() && arg.MapType != MapType.Projection;
+            if(arg.MapType == MapType.Projection)
+                return false;
+            if (arg.CustomRecordType)
+                return true;
+
+            return arg.DestinationType.IsRecordType(arg);
         }
 
         protected override bool CanInline(Expression source, Expression? destination, CompileArgument arg)
@@ -51,7 +56,7 @@
             }
 
 
             return RecordInlineExpression(source, destination, arg, installExpr); // Activator field when not include in public ctor
         }
 
         private Expression? RecordInlineExpression(Expression source, Expression? destination, CompileArgument arg, Expression installExpr)
@@ -101,7 +106,7 @@
                             binEx.Right is ConstantExpression { Value: null })
                             adapt = condEx.IfFalse;
                     }
                     var destinationCompareNull = Expression.Equal(destination, Expression.Constant(null, destination.Type));
                     var sourceCondition = Expression.NotEqual(member.Getter, Expression.Constant(null, member.Getter.Type));
                     var destinationCanbeNull = Expression.Condition(destinationCompareNull, member.DestinationMember.Type.CreateDefault(), member.DestinationMember.GetExpression(destination));
                     adapt = Expression.Condition(sourceCondition, adapt, destinationCanbeNull);
@@ -152,7 +157,7 @@
                    contructorMembers.Any(x => string.Equals(x.Name, member.Name, StringComparison.InvariantCultureIgnoreCase)))
                     continue;
 
                 lines.Add(Expression.Bind((MemberInfo)member.Info, Expression.MakeMemberAccess(destination, (MemberInfo)member.Info)));
             }
 
             return lines;
@@ -199,11 +204,11 @@
 
                     if (member.DestinationMember is PropertyModel && member.DestinationMember.Type.IsValueType 
                         || member.DestinationMember.Type.IsMapsterPrimitive()
-                        || member.DestinationMember.Type.IsRecordType())
+                        || member.DestinationMember.Type.IsRecordType(arg))
                     {
 
                         Expression adapt;
-                        if (member.DestinationMember.Type.IsRecordType())
+                        if (member.DestinationMember.Type.IsRecordType(arg))
                             adapt = arg.Context.Config.CreateMapInvokeExpressionBody(member.Getter.Type, member.DestinationMember.Type, member.Getter);
                         else
                             adapt = CreateAdaptExpression(member.Getter, member.DestinationMember.Type, arg, member, result);
@@ -227,7 +232,7 @@
 
                                 Expression destMemberVar2 = var2Param.DestinationMember.GetExpression(var2Param.Destination);
                                 var ParamLambdaVar2 = destMemberVar2;
-                                if(member.DestinationMember.Type.IsRecordType())
+                                if(member.DestinationMember.Type.IsRecordType(arg))
                                     ParamLambdaVar2 = arg.Context.Config.CreateMapInvokeExpressionBody(member.Getter.Type, member.DestinationMember.Type, destMemberVar2);
 
                                 var blocksVar2 = Expression.Block(SetValueTypeAutoPropertyByReflection(member, ParamLambdaVar2, classModel));

src/Mapster/Compile/PreCompileArgument.cs

@@ -9,5 +9,6 @@ public class PreCompileArgument
         public Type DestinationType;
         public MapType MapType;
         public bool ExplicitMapping;
+        public bool CustomRecordType;
     }
 }

src/Mapster/Models/TypeTuple.cs

@@ -39,5 +39,15 @@ public TypeTuple(Type source, Type destination)
             Source = source;
             Destination = destination;
         }
+
+        public static TypeTuple ForDestinationType(Type destination)
+        {
+            return new TypeTuple(typeof(void), destination);
+        }
+
+        public static TypeTuple ForDestinationType(TypeTuple tuple)
+        {
+            return new TypeTuple(typeof(void), tuple.Destination);
+        }
     }
 }

src/Mapster/Settings/ValueAccessingStrategy.cs

@@ -117,7 +117,7 @@ public static class ValueAccessingStrategy
 
                 var propertyType = member.Type;
                 if (propertyName.StartsWith(sourceMemberName) &&
-                    (propertyType.IsPoco() || propertyType.IsRecordType()))
+                    (propertyType.IsPoco() || propertyType.IsRecordType(arg)))
                 {
                     var exp = member.GetExpression(source);
                     var ifTrue = GetDeepFlattening(exp, propertyName.Substring(sourceMemberName.Length).TrimStart('_'), arg);
@@ -168,7 +168,7 @@ private static IEnumerable<string> GetDeepUnflattening(IMemberModel destinationM
                     yield return member.Name;
                 }
                 else if (propertyName.StartsWith(destMemberName) &&
-                    (propertyType.IsPoco() || propertyType.IsRecordType()))
+                    (propertyType.IsPoco() || propertyType.IsRecordType(arg)))
                 {
                     foreach (var prop in GetDeepUnflattening(member, propertyName.Substring(destMemberName.Length).TrimStart('_'), arg))
                     {

src/Mapster/TypeAdapterConfig.cs

@@ -201,7 +201,7 @@ public TypeAdapterSetter ForType(Type sourceType, Type destinationType)
 		/// <returns></returns>
 		public TypeAdapterSetter<TDestination> ForDestinationType<TDestination>()
         {
-            var key = new TypeTuple(typeof(void), typeof(TDestination));
+            var key = TypeTuple.ForDestinationType(typeof(TDestination));
             var settings = GetSettings(key);
             return new TypeAdapterSetter<TDestination>(settings, this);
         }
@@ -214,7 +214,7 @@ public TypeAdapterSetter<TDestination> ForDestinationType<TDestination>()
 		/// <returns></returns>
 		public TypeAdapterSetter ForDestinationType(Type destinationType)
         {
-            var key = new TypeTuple(typeof(void), destinationType);
+            var key = TypeTuple.ForDestinationType(destinationType);
             var settings = GetSettings(key);
             return new TypeAdapterSetter(settings, this);
         }
@@ -593,6 +593,7 @@ internal TypeAdapterSettings GetMergedSettings(TypeTuple tuple, MapType mapType)
                 DestinationType = tuple.Destination,
                 MapType = mapType,
                 ExplicitMapping = RuleMap.ContainsKey(tuple),
+                CustomRecordType = GetSettings(TypeTuple.ForDestinationType(tuple)).DestinationAsRecord.GetValueOrDefault(),
             };
 
             //auto add setting if there is attr setting

src/Mapster/TypeAdapterSetter.cs

@@ -510,6 +510,36 @@ public TypeAdapterSetter<TDestination> AfterMappingInline(Expression<Action<TDes
             Settings.AfterMappingFactories.Add(arg => lambda);
             return this;
         }
+
+        public TypeAdapterSetter<TDestination> DestinationAsRecord(bool value)
+        {
+            this.CheckCompiled();
+
+            Settings.DestinationAsRecord = value;
+            return this;
+        }
+
+        public TypeAdapterSetter<TDestination> UseDestinationValue<TDestinationMember> (Expression<Func<TDestination, TDestinationMember>> destinationMember)
+        {
+            this.CheckCompiled();
+            var memberName = destinationMember.GetMemberPath()!;
+
+            if (memberName != null)
+            {
+                Settings.UseDestinationMember.Add(memberName);
+            }
+
+            return this;
+        }
+
+        public TypeAdapterSetter UseDestinationValue(string destinationMemberName)
+        {
+            this.CheckCompiled();
+
+            Settings.UseDestinationMember.Add(destinationMemberName);
+
+            return this;
+        }
     }
 
     [System.Diagnostics.CodeAnalysis.SuppressMessage("Minor Code Smell", "S4136:Method overloads should be grouped together", Justification = "<Pending>")]

src/Mapster/TypeAdapterSettings.cs

@@ -185,6 +185,17 @@ public Action<TypeAdapterConfig>? Fork
             set => Set(nameof(Fork), value);
         }
 
+        public bool? DestinationAsRecord
+        {
+            get => Get(nameof(PreserveReference));
+            set => Set(nameof(PreserveReference), value);
+        }
+
+        public List<string> UseDestinationMember
+        {
+            get => Get(nameof(UseDestinationMember), () => new List<string>());
+        }
+
         internal bool Compiled { get; set; }
 
         public TypeAdapterSettings Clone()

src/Mapster/Utils/ReflectionUtils.cs

@@ -193,7 +193,17 @@ public static Type UnwrapNullable(this Type type)
             return type.IsNullable() ? type.GetGenericArguments()[0] : type;
         }
 
-        public static bool IsRecordType(this Type type)
+        public static bool IsRecordType(this Type type, CompileArgument arg)
+        {
+            return arg.Settings.DestinationAsRecord.GetValueOrDefault() || type.IsRecordType();
+        }
+
+        public static bool IsRecordType(this Type type, PreCompileArgument arg)
+        {
+            return arg.CustomRecordType || type.IsRecordType();
+        }
+
+        private static bool IsRecordType(this Type type)
         {
             //not nullable
             if (type.IsNullable())