Improvement to map a constructor in a selector with no params.

Author: BlaiseD

Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <Authors>Jimmy Bogard</Authors>
     <LangVersion>latest</LangVersion>
-    <VersionPrefix>3.1.0</VersionPrefix>
+    <VersionPrefix>3.1.1-preview01</VersionPrefix>
     <WarningsAsErrors>true</WarningsAsErrors>
     <NoWarn>$(NoWarn);1701;1702;1591</NoWarn>
   </PropertyGroup>

src/AutoMapper.Extensions.ExpressionMapping/Extensions/VisitorExtensions.cs

@@ -111,9 +111,9 @@ public static ParameterExpression GetParameterExpression(this Expression express
                 case ExpressionType.Parameter:
                     return (ParameterExpression)expression;
                 case ExpressionType.Quote:
-                    return GetParameterExpression(GetMemberExpression((LambdaExpression)((UnaryExpression)expression).Operand));
+                    return GetParameterExpression(((UnaryExpression)expression).Operand);
                 case ExpressionType.Lambda:
-                    return GetParameterExpression(GetMemberExpression((LambdaExpression)expression));
+                    return GetParameterExpression(((LambdaExpression)expression).Body);
                 case ExpressionType.ConvertChecked:
                 case ExpressionType.Convert:
                     var ue = expression as UnaryExpression;

src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs

@@ -129,6 +129,14 @@ protected override Expression VisitLambda<T>(Expression<T> node)
             return mapped;
         }
 
+        protected override Expression VisitNew(NewExpression node)
+        {
+            if (this.TypeMappings.TryGetValue(node.Type, out Type newType))
+                return Expression.New(newType);
+
+            return base.VisitNew(node);
+        }
+
         protected override Expression VisitMemberInit(MemberInitExpression node)
         {
             if (this.TypeMappings.TryGetValue(node.Type, out Type newType))

tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/XpressionMapperTests.cs

@@ -429,6 +429,32 @@ public void Map__select_method_projecting_to_model_type()
             Assert.True(things.Count == 2);
         }
 
+        [Fact]
+        public void Map_MemberInit()
+        {
+            //Arrange
+            Expression<Func<ThingModel, ThingModel>> selection = s => new ThingModel { Car = s.Car };
+
+            //Act
+            Expression<Func<Thing, Thing>> selectionMapped = mapper.MapExpression<Expression<Func<Thing, Thing>>>(selection);
+
+            //Assert
+            Assert.NotNull(selectionMapped);
+        }
+
+        [Fact]
+        public void Map_Constructor_NoParams()
+        {
+            //Arrange
+            Expression<Func<ThingModel, ThingModel>> selection = s => new ThingModel();
+
+            //Act
+            Expression<Func<Thing, Thing>> selectionMapped = mapper.MapExpression<Expression<Func<Thing, Thing>>>(selection);
+
+            //Assert
+            Assert.NotNull(selectionMapped);
+        }
+
         [Fact]
         public void Map__select_method_where_parent_type_is_grandchild_type()
         {