Add support for custom values with [EnumMember]

Author: mythz

src/ServiceStack.Text/Common/ITypeSerializer.cs

@@ -54,6 +54,7 @@ public interface ITypeSerializer
         void WriteDecimal(TextWriter writer, object decimalValue);
         void WriteEnum(TextWriter writer, object enumValue);
         void WriteEnumFlags(TextWriter writer, object enumFlagValue);
+        void WriteEnumMember(TextWriter writer, object enumFlagValue);
 
         //object EncodeMapKey(object value);
 

src/ServiceStack.Text/Common/JsWriter.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Runtime.CompilerServices;
+using System.Runtime.Serialization;
 using ServiceStack.Text.Json;
 using ServiceStack.Text.Jsv;
 
@@ -282,9 +283,13 @@ public WriteObjectDelegate GetValueTypeToStringMethod(Type type)
             else
             {
                 if (underlyingType.IsEnum)
-                    return type.FirstAttribute<FlagsAttribute>() != null
-                        ? (WriteObjectDelegate)Serializer.WriteEnumFlags
-                        : Serializer.WriteEnum;
+                {
+                    if (type.HasAttribute<DataContractAttribute>())
+                        return Serializer.WriteEnumMember;
+                    if (type.HasAttribute<FlagsAttribute>())
+                        return Serializer.WriteEnumFlags;
+                    return Serializer.WriteEnum;
+                }
             }
 
             if (type.HasInterface(typeof(IFormattable)))

src/ServiceStack.Text/Common/ParseUtils.cs

@@ -11,6 +11,8 @@
 //
 
 using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.Serialization;
 
 namespace ServiceStack.Text.Common
 {
@@ -69,6 +71,21 @@ public static object TryParseEnum(Type enumType, string str)
                     str = str.Replace("_", "");
             }
 
+            if (enumType.HasAttribute<DataContractAttribute>())
+            {
+                var enumNames = Enum.GetNames(enumType);
+                var enumValues = Enum.GetValues(enumType);
+                var i = 0;                
+                foreach (var enumValue in enumValues)
+                {
+                    var enumName = enumNames[i++];
+                    var mi = enumType.GetMember(enumName)[0];
+                    var useValue = mi.FirstAttribute<EnumMemberAttribute>()?.Value ?? enumValue;
+                    if (string.Equals(str, useValue.ToString(), StringComparison.OrdinalIgnoreCase))
+                        return enumValue;
+                }
+            }
+            
             return Enum.Parse(enumType, str, ignoreCase: true);
         }
     }

src/ServiceStack.Text/Json/JsonTypeSerializer.cs

@@ -5,6 +5,7 @@
 using System.Globalization;
 using System.IO;
 using System.Runtime.CompilerServices;
+using System.Runtime.Serialization;
 using System.Text;
 using ServiceStack.Text.Common;
 using ServiceStack.Text.Pools;
@@ -298,6 +299,17 @@ public void WriteEnumFlags(TextWriter writer, object enumFlagValue)
             JsWriter.WriteEnumFlags(writer, enumFlagValue);
         }
 
+        public void WriteEnumMember(TextWriter writer, object enumValue)
+        {
+            if (enumValue == null) return;
+
+            var enumType = enumValue.GetType();
+            var mi = enumType.GetMember(enumValue.ToString());
+            var enumMemberAttr = mi[0].FirstAttribute<EnumMemberAttribute>();
+            var useValue = enumMemberAttr?.Value ?? enumValue;
+            WriteRawString(writer, useValue.ToString());
+        }
+
         public ParseStringDelegate GetParseFn<T>()
         {
             return JsonReader.Instance.GetParseFn<T>();

src/ServiceStack.Text/Jsv/JsvTypeSerializer.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Globalization;
 using System.IO;
+using System.Runtime.Serialization;
 using ServiceStack.Text.Common;
 using ServiceStack.Text.Json;
 #if NETSTANDARD2_0
@@ -255,6 +256,17 @@ public void WriteEnumFlags(TextWriter writer, object enumFlagValue)
             JsWriter.WriteEnumFlags(writer, enumFlagValue);
         }
 
+        public void WriteEnumMember(TextWriter writer, object enumValue)
+        {
+            if (enumValue == null) return;
+
+            var enumType = enumValue.GetType();
+            var mi = enumType.GetMember(enumValue.ToString());
+            var enumMemberAttr = mi[0].FirstAttribute<EnumMemberAttribute>();
+            var useValue = enumMemberAttr?.Value ?? enumValue;
+            writer.Write(enumValue.ToString());
+        }
+
         public object EncodeMapKey(object value)
         {
             return value;

tests/ServiceStack.Text.Tests/EnumTests.cs

@@ -206,6 +206,42 @@ public void Does_write_EnumValues_when_ExcludeDefaultValues()
                 }.ToJson(), Is.EqualTo("{}"));
             }
         }
+        
+        [DataContract]
+        public enum Day
+        {
+            [EnumMember(Value = "MON")]
+            Monday,
+            [EnumMember(Value = "TUE")]
+            Tuesday,
+            [EnumMember(Value = "WED")]
+            Wednesday,
+            [EnumMember(Value = "THU")]
+            Thursday,
+            [EnumMember(Value = "FRI")]
+            Friday,
+            [EnumMember(Value = "SAT")]
+            Saturday,
+            [EnumMember(Value = "SUN")]
+            Sunday,            
+        }
+
+        class EnumMemberDto
+        {
+            public Day Day { get; set; }
+        }
+
+        [Test]
+        public void Does_serialize_EnumMember_Value()
+        {
+            var dto = new EnumMemberDto {Day = Day.Sunday};
+            var json = dto.ToJson();
+            
+            Assert.That(json, Is.EqualTo("{\"Day\":\"SUN\"}"));
+
+            var fromDto = json.FromJson<EnumMemberDto>();
+            Assert.That(fromDto.Day, Is.EqualTo(Day.Sunday));
+        }
 
     }
 }