Add support for DateOnly

Support is introduced via custom extensibility across all supported serializers.
For readability, when the value can be read by a human, we serialize to ISO 8601 format ("O" or roundtrip), and as the DayNumber integrer otherwise.

Fixes #78

Author: kzu

readme.md

@@ -19,13 +19,14 @@ public record Product(string Category, string Id)
 {
   public string? Title { get; init; }
   public double Price { get; init; }
+  public DateOnly Created { get; init; }
 }
 ```
 
 > NOTE: entity can have custom constructor, key properties can be read-only, 
 > and it doesn't need to inherit from anything, implement any interfaces or use 
 > any custom attributes (unless you want to). As shown above, it can even be 
-> a simple record type!
+> a simple record type, with support for .NET 6 DateOnly type to boot!
 
 The entity can be stored and retrieved with:
 

src/TableStorage.Bson/BsonDocumentSerializer.cs

@@ -1,5 +1,7 @@
 //<auto-generated/>
 #nullable enable
+using System;
+using System.Globalization;
 using System.IO;
 using Newtonsoft.Json;
 
@@ -11,7 +13,18 @@ namespace Devlooped
     /// </summary>
     partial class BsonDocumentSerializer : IBinaryDocumentSerializer
     {
-        static readonly JsonSerializer serializer = new JsonSerializer();
+        static readonly JsonSerializer serializer =
+#if NET6_0_OR_GREATER
+            JsonSerializer.Create(new JsonSerializerSettings
+            {
+                Converters =
+                {
+                    new DateOnlyJsonConverter(),
+                }
+            });
+#else
+            new JsonSerializer();
+#endif
 
         /// <summary>
         /// Default instance of the serializer.
@@ -40,5 +53,16 @@ public byte[] Serialize<T>(T value)
             serializer.Serialize(writer, value);
             return mem.ToArray();
         }
+
+#if NET6_0_OR_GREATER
+        class DateOnlyJsonConverter : JsonConverter<DateOnly>
+        {
+            public override DateOnly ReadJson(JsonReader reader, Type objectType, DateOnly existingValue, bool hasExistingValue, JsonSerializer serializer)
+                => DateOnly.Parse((string)reader.Value, CultureInfo.InvariantCulture);
+
+            public override void WriteJson(JsonWriter writer, DateOnly value, JsonSerializer serializer)
+                => writer.WriteValue(value.ToString("O", CultureInfo.InvariantCulture));
+        }
+#endif
     }
 }

src/TableStorage.Bson/TableStorage.Bson.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <AssemblyName>Devlooped.TableStorage.Bson</AssemblyName>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
     <IsPackable>true</IsPackable>
     <Description>A BSON binary serializer for use with document-based repositories.
 

src/TableStorage.MessagePack/MessagePackDocumentSerializer.cs

@@ -1,6 +1,10 @@
 //<auto-generated/>
 #nullable enable
+using System;
+using System.Collections.Generic;
 using MessagePack;
+using MessagePack.Formatters;
+using MessagePack.Resolvers;
 
 namespace Devlooped
 {
@@ -20,12 +24,47 @@ partial class MessagePackDocumentSerializer : IBinaryDocumentSerializer
         /// <summary>
         /// Initializes the document serializer with the given optional serializer options.
         /// </summary>
-        public MessagePackDocumentSerializer(MessagePackSerializerOptions? options = default) => this.options = options;
+        public MessagePackDocumentSerializer(MessagePackSerializerOptions? options = default)
+        {
+            this.options = options;
+#if NET6_0_OR_GREATER
+            this.options = (options ?? MessagePackSerializerOptions.Standard)
+                .WithResolver(CompositeResolver.Create(
+                    StandardResolver.Instance,
+                    DateOnlyFormatterResolver.Instance));
+#endif
+        }
 
         /// <inheritdoc />
         public T? Deserialize<T>(byte[] data) => data.Length == 0 ? default : MessagePackSerializer.Deserialize<T>(data, options);
 
         /// <inheritdoc />
         public byte[] Serialize<T>(T value) => value == null ? new byte[0] : MessagePackSerializer.Serialize(value.GetType(), value, options);
+
+#if NET6_0_OR_GREATER
+        class DateOnlyFormatterResolver : IFormatterResolver
+        {
+            public static IFormatterResolver Instance = new DateOnlyFormatterResolver();
+
+            public IMessagePackFormatter<T> GetFormatter<T>()
+            {
+                if (typeof(T) == typeof(DateOnly))
+                    return (IMessagePackFormatter<T>)DateOnlyFormatter.Instance;
+
+                return null!;
+            }
+
+            class DateOnlyFormatter : IMessagePackFormatter<DateOnly>
+            {
+                public static readonly IMessagePackFormatter<DateOnly> Instance = new DateOnlyFormatter();
+
+                public void Serialize(ref MessagePackWriter writer, DateOnly value, MessagePackSerializerOptions options)
+                    => writer.Write(value.DayNumber);
+
+                public DateOnly Deserialize(ref MessagePackReader reader, MessagePackSerializerOptions options)
+                    => DateOnly.FromDayNumber(reader.ReadInt32());
+            }
+        }
+#endif
     }
 }

src/TableStorage.MessagePack/TableStorage.MessagePack.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <AssemblyName>Devlooped.TableStorage.MessagePack</AssemblyName>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
     <IsPackable>true</IsPackable>
     <Description>A MessagePack binary serializer for use with document-based repositories.
 

src/TableStorage.Newtonsoft/JsonDocumentSerializer.cs

@@ -1,5 +1,6 @@
 //<auto-generated/>
 #nullable enable
+using System;
 using System.Globalization;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
@@ -38,6 +39,9 @@ partial class JsonDocumentSerializer : IStringDocumentSerializer
                     DateTimeFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffK",
                     DateTimeStyles = DateTimeStyles.AdjustToUniversal
                 },
+#if NET6_0_OR_GREATER
+                new DateOnlyJsonConverter(),
+#endif
             },
             DateFormatHandling = DateFormatHandling.IsoDateFormat,
             DateFormatString = "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffK",
@@ -68,5 +72,16 @@ public JsonDocumentSerializer()
 
         /// <inheritdoc />
         public string Serialize<T>(T value) => JsonConvert.SerializeObject(value, settings);
+
+#if NET6_0_OR_GREATER
+        class DateOnlyJsonConverter : JsonConverter<DateOnly>
+        {
+            public override DateOnly ReadJson(JsonReader reader, Type objectType, DateOnly existingValue, bool hasExistingValue, JsonSerializer serializer)
+                => DateOnly.Parse((string)reader.Value, CultureInfo.InvariantCulture);
+
+            public override void WriteJson(JsonWriter writer, DateOnly value, JsonSerializer serializer)
+                => writer.WriteValue(value.ToString("O", CultureInfo.InvariantCulture));
+        }
+#endif
     }
 }

src/TableStorage.Newtonsoft/TableStorage.Newtonsoft.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <AssemblyName>Devlooped.TableStorage.Newtonsoft</AssemblyName>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
     <IsPackable>true</IsPackable>
     <Description>A Newtonsoft.Json-based serializer for use with document-based repositories.
 

src/TableStorage.Protobuf/ProtobufDocumentSerializer.cs

@@ -1,7 +1,9 @@
 //<auto-generated/>
 #nullable enable
+using System;
 using System.IO;
 using ProtoBuf;
+using ProtoBuf.Meta;
 
 namespace Devlooped
 {
@@ -16,6 +18,18 @@ partial class ProtobufDocumentSerializer : IBinaryDocumentSerializer
         /// </summary>
         public static IDocumentSerializer Default { get; } = new ProtobufDocumentSerializer();
 
+#if NET6_0_OR_GREATER
+        static ProtobufDocumentSerializer()
+        {
+            RuntimeTypeModel.Default.SetSurrogate<DateOnly, int>(
+                UnderlyingToSurrogate, 
+                SurrogateToUnderlying);
+        }
+
+        static int UnderlyingToSurrogate(DateOnly value) => value.DayNumber;
+        static DateOnly SurrogateToUnderlying(int value) => DateOnly.FromDayNumber(value);
+#endif
+
         /// <inheritdoc />
         public T? Deserialize<T>(byte[] data)
         {

src/TableStorage.Protobuf/TableStorage.Protobuf.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <AssemblyName>Devlooped.TableStorage.Protobuf</AssemblyName>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFrameworks>netstandard2.0;net6.0</TargetFrameworks>
     <IsPackable>true</IsPackable>
     <Description>A Protocol Buffers binary serializer for use with document-based repositories.
 

src/TableStorage/DocumentSerializer.cs

@@ -1,5 +1,7 @@
 //<auto-generated/>
 #nullable enable
+using System;
+using System.Globalization;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 
@@ -27,10 +29,24 @@ partial class DocumentSerializer : IStringDocumentSerializer
             Converters =
             {
                 // Enums should persist/parse with their string values instead
-                new JsonStringEnumConverter(allowIntegerValues: false)
+                new JsonStringEnumConverter(allowIntegerValues: false),
+#if NET6_0_OR_GREATER
+                new DateOnlyJsonConverter()
+#endif
             }
         };
 
+#if NET6_0_OR_GREATER
+        public class DateOnlyJsonConverter : JsonConverter<DateOnly>
+        {
+            public override DateOnly Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) 
+                => DateOnly.Parse(reader.GetString()?.Substring(0, 10) ?? "", CultureInfo.InvariantCulture);
+            
+            public override void Write(Utf8JsonWriter writer, DateOnly value, JsonSerializerOptions options) 
+                => writer.WriteStringValue(value.ToString("O", CultureInfo.InvariantCulture));
+        }
+#endif
+
         /// <summary>
         /// Default instance of the serializer.
         /// </summary>