Fix nullable porperties serialization exception in EntryConvert

Creating an instance of the nullable primitive using the underlying type.

Author: DosenSuppe

src/Moryx/Serialization/EntryConvert/EntryConvert.cs

@@ -111,10 +111,12 @@ private static EntryValue CreateEntryValue(PropertyInfo property, ICustomSeriali
                 isReadOnly = readOnlyAtt?.IsReadOnly ?? false;
             }
 
+            var type = TransformType(property.PropertyType);
+
             // Prepare object
             var entryValue = new EntryValue
             {
-                Type = TransformType(property.PropertyType),
+                Type = type,
                 UnitType = customSerialization.GetUnitTypeByAttributes(property),
                 IsReadOnly = isReadOnly,
                 Possible = customSerialization.PossibleValues(property.PropertyType, property)
@@ -126,10 +128,14 @@ private static EntryValue CreateEntryValue(PropertyInfo property, ICustomSeriali
                 entryValue.Default = defaultAttribute.Value.ToString();
             else if (entryValue.Possible != null && entryValue.Possible.Length >= 1)
                 entryValue.Default = entryValue.Possible[0];
-            else if (property.PropertyType.IsValueType)
-                entryValue.Default = Activator.CreateInstance(property.PropertyType).ToString();
-
-            // Value types should have the default value as current value
+            else if (property.PropertyType.IsValueType)
+            {
+                var underlyingType = Nullable.GetUnderlyingType(property.PropertyType);
+                entryValue.Default = underlyingType != null 
+                    ? Activator.CreateInstance(underlyingType).ToString() 
+                    : Activator.CreateInstance(property.PropertyType).ToString();
+            }
+            // Value types should have the default value as current value
             if (ValueOrStringType(property.PropertyType))
                 entryValue.Current = ConvertToString(entryValue.Default, customSerialization.FormatProvider);
 
@@ -313,7 +319,10 @@ public static Entry EncodeObject(object instance, ICustomSerialization customSer
                         convertedProperty.SubEntries = subEntry.SubEntries;
                         break;
                     case EntryValueType.Exception:
-                        convertedProperty.Value.Current = ExceptionPrinter.Print((Exception)value);
+                        //if (value is Exception exceptionValue)
+                        //{
+                            convertedProperty.Value.Current = ExceptionPrinter.Print((Exception)value);
+                        //}
                         break;
                     case EntryValueType.Stream:
                         var stream = value as Stream;

src/Moryx/Serialization/EntryConvert/EntryConvertGenerator.cs

@@ -55,7 +55,11 @@ public static EntryValueType TransformType(Type propertyType)
             else if (propertyType == typeof(Double))
             {
                 valueType = EntryValueType.Double;
-            }
+            }
+            //else if (propertyType == typeof(String) || propertyType == typeof(string))
+            //{
+            //    valueType = EntryValueType.String;
+            //}
             else if (propertyType.IsEnum)
             {
                 valueType = EntryValueType.Enum;

src/Tests/Moryx.Tests/Serialization/DummyClass.cs

@@ -53,4 +53,9 @@ public enum DummyEnum
         ValueA,
         ValueB
     }
+
+    public class NullablePropertiesClass
+    {
+        public int? Value { get; set; } = 0;
+    }
 }

src/Tests/Moryx.Tests/Serialization/SerializationTests.cs

@@ -855,6 +855,14 @@ public void MemoryStreamDecodeReuseCurrentStreamInitSizeIsGreaterThanNewData()
             Assert.AreSame(streamInstanceToCheck, targetStreamDummy.MemoryStream);
         }
 
+        [Test(Description = "Testing nullable properties")]
+        public void NullableProperty()
+        {
+            var nullablePropertiesObject = new NullablePropertiesClass();
+
+            Assert.DoesNotThrow(() => EntryConvert.EncodeObject(nullablePropertiesObject));
+        }
+
         [Test(Description = "Encodes a FileStream")]
         public void FileStreamEncode()
         {