Null propagation Improvements

src/Mapster.Tests/WhenNullPropagationRegression.cs

@@ -0,0 +1,109 @@
+using Mapster.Tests.Classes;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Shouldly;
+using System;
+
+namespace Mapster.Tests;
+
+[TestClass]
+public class WhenNullPropagationRegression
+{
+    [TestMethod]
+    public void WhenCustomDefaultWorked()
+    {
+        string customdefault = "42";
+
+        TypeAdapterConfig<SimplePocoToNullPropagation, SimpleDtoToNullPropagation>.NewConfig()
+                .Map(dest => dest.AnotherName, src => src.Name).SourceDefaultValue(customdefault)
+                .Map(dest => dest.LastModified, src => DateTime.Now)
+                .Compile();
+
+        var poco = new SimplePocoToNullPropagation { Id = Guid.NewGuid(), Name = null};
+
+        var dto = poco.Adapt<SimpleDtoToNullPropagation>();
+
+        dto.Id.ShouldBe(poco.Id);
+        dto.Name.ShouldBe(null);
+        dto.AnotherName.ShouldBe(customdefault);
+    }
+
+    [TestMethod]
+    public void WhenCustomDefaultMapPathWorked()
+    {
+        string customdefault = "Default Location";
+
+        TypeAdapterConfig<PocoToPathNullPropagation, DtoToPathNullPropagation>.NewConfig()
+                .Map(dest => dest.Location, src => src.Child.Address.Location).SourceDefaultValue(customdefault);
+
+        var poco = new PocoToPathNullPropagation
+        {
+            Id = Guid.NewGuid(),
+            Child = new()
+        };
+
+        var dto = poco.Adapt<DtoToPathNullPropagation>();
+        dto.Id.ShouldBe(poco.Id);
+        dto.Location.ShouldBe(customdefault);
+    }
+
+    [TestMethod]
+    public void WhenThrowWhenNullWorked()
+    {
+        TypeAdapterConfig<PocoToPathNullPropagation, DtoToPathNullPropagation>.NewConfig()
+                .Map(dest => dest.Location, src => src.Child.Address.Location).ThrowWhenNull();
+
+        var poco = new PocoToPathNullPropagation
+        {
+            Id = Guid.NewGuid(),
+            Child = new()
+        };
+
+        Should.Throw<NullReferenceException>(() =>
+        {
+            var dto = poco.Adapt<DtoToPathNullPropagation>();
+        });
+    }
+
+    #region Classes
+
+    public class SimplePocoToNullPropagation
+    {
+        public Guid Id { get; set; }
+        public string? Name { get; set; }
+    }
+
+    public class SimpleDtoToNullPropagation
+    {
+        public Guid Id { get; set; }
+        public string Name { get; set; }
+
+        public string AnotherName { get; set; }
+        public DateTime LastModified { get; set; }
+
+    }
+
+    public class PocoToPathNullPropagation
+    {
+        public Guid Id { get; set; }
+        public ChildPocoToNullPropagation? Child { get; set; }
+    }
+
+    public class DtoToPathNullPropagation
+    {
+        public Guid Id { get; set; }
+        public Address Address { get; set; }
+        public string Location { get; set; }
+    }
+
+    public class ChildPocoToNullPropagation
+    {
+        public AddressNullPropagation? Address { get; set; }
+    }
+    public class AddressNullPropagation
+    {
+        public string? Number { get; set; }
+        public string? Location { get; set; }
+    }
+
+    #endregion Classes
+}

src/Mapster/Adapters/BaseAdapter.cs

@@ -60,6 +60,8 @@ protected virtual void DecorateRule(TypeAdapterRule rule) { }
 
         protected virtual bool CanInline(Expression source, Expression? destination, CompileArgument arg)
         {
+            if (arg.Settings.Resolvers.Any(x=>x.IsThrowWhenNull))
+                return false;
             if (arg.MapType == MapType.Projection)
                 return true;
 

src/Mapster/Adapters/BaseClassAdapter.cs

@@ -54,13 +54,26 @@ select fn(src, destinationMember, arg))
                     Destination = (ParameterExpression?)destination,
                     UseDestinationValue = arg.MapType != MapType.Projection && destinationMember.UseDestinationValue(arg),
                 };
-                if (getter != null)
-                {
-                    propertyModel.Getter = arg.MapType == MapType.Projection 
-                        ? getter 
-                        : getter.ApplyNullPropagation();
-                    properties.Add(propertyModel);
-                }
+				if (getter != null)
+				{
+					var customDefault = arg.Settings.Resolvers
+						.Where(x=>x.DefaultValue != null && x.DestinationMemberName == destinationMember.Name)
+						.FirstOrDefault()?.DefaultValue;
+
+					var whenNullisThrow = arg.Settings.Resolvers
+					   .Where(x => x.IsThrowWhenNull && x.DestinationMemberName == destinationMember.Name)
+					   .FirstOrDefault()?.IsThrowWhenNull;
+
+					if (whenNullisThrow == true)
+                        propertyModel.Getter = getter;
+					else
+					{
+						propertyModel.Getter = arg.MapType == MapType.Projection
+						? getter
+						: getter.ApplyNullPropagation(customDefault);
+					}
+				    properties.Add(propertyModel);
+				}
                 else
                 {
                     if (arg.Settings.IgnoreNonMapped != true &&

src/Mapster/Adapters/ClassAdapter.cs

@@ -161,7 +161,18 @@ protected override Expression CreateBlockExpression(Expression source, Expressio
                     tuple.Item1.Add(adapt);
                 }
                 else
-                    lines.Add(adapt);
+                {
+                    var whenNullisThrow = arg.Settings.Resolvers
+                       .Where(x => x.IsThrowWhenNull && x.DestinationMemberName == member.DestinationMember.Name)
+                       .FirstOrDefault()?.IsThrowWhenNull;
+
+                    if (whenNullisThrow == true)
+                    {
+                        lines.Add(adapt.ApplyThrowPropagation());
+                    }
+                    else
+                        lines.Add(adapt);
+                }
             }
 
             if (conditions != null)

src/Mapster/Models/InvokerModel.cs

@@ -9,6 +9,8 @@ public class InvokerModel
         public LambdaExpression? Invoker { get; set; }
         public string? SourceMemberName { get; set; }
         public LambdaExpression? Condition { get; set; }
+        public LambdaExpression? DefaultValue { get; set; }
+        public bool IsThrowWhenNull { get; set; }
         public bool IsChildPath { get; set; }
 
         public InvokerModel? Next(ParameterExpression source, string destMemberName)