Don't invoke the type converter when the incoming complex type value is null

Author: christiaanderidder

src/PhenX.EntityFrameworkCore.BulkInsert/Metadata/PropertyAccessor.cs

@@ -27,9 +27,11 @@ internal static class PropertyAccessor
         {
             // Validate the converter input type matches property type
             var converterParamType = converter.Parameters[0].Type;
-            if (!converterParamType.IsAssignableFrom(propertyType) && !propertyType.IsAssignableFrom(converterParamType))
+            if (!converterParamType.IsAssignableFrom(propertyType) &&
+                !propertyType.IsAssignableFrom(converterParamType))
             {
-                throw new ArgumentException($"Converter input must be assignable from property type ({propertyType} -> {converterParamType})");
+                throw new ArgumentException(
+                    $"Converter input must be assignable from property type ({propertyType} -> {converterParamType})");
             }
 
             // If property type != converter param, convert
@@ -39,7 +41,18 @@ internal static class PropertyAccessor
                 converterInput = Expression.Convert(getterExpression, converterParamType);
             }
 
-            getterExpression = Expression.Invoke(converter, converterInput);
+            var invokeConverter = Expression.Invoke(converter, converterInput);
+
+            if (propertyType.IsClass)
+            {
+                var nullCondition = Expression.Equal(getterExpression, Expression.Constant(null, propertyType));
+                var nullResult = Expression.Constant(null, converter.ReturnType);
+                getterExpression = Expression.Condition(nullCondition, nullResult, invokeConverter);
+            }
+            else
+            {
+                getterExpression = invokeConverter;
+            }
 
             propertyType = getterExpression.Type;
         }