Add TypeConverterJsonAdapter. (#19)

Authored-by: Konstantin Sharon <[email protected]>

Author: NN---

ClassLibraries/Macross.Json.Extensions/Code/System.Text.Json.Serialization/TypeConverterJsonAdapter.cs

@@ -0,0 +1,39 @@
+using System.ComponentModel;
+using System.Linq;
+using System.Reflection;
+
+namespace System.Text.Json.Serialization
+{
+	/// <summary>
+	/// Adapter between <see cref="TypeConverter"/> and <see cref="JsonConverter"/>.
+	/// </summary>
+	/// <typeparam name="T">The type being converted.</typeparam>
+	public class TypeConverterJsonAdapter<T> : JsonConverter<T>
+	{
+		/// <inheritdoc/>
+		public override T Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+		{
+			TypeConverter converter = TypeDescriptor.GetConverter(typeToConvert);
+			string text = reader.GetString();
+			return (T)converter.ConvertFromString(text);
+		}
+
+		/// <inheritdoc/>
+		public override void Write(Utf8JsonWriter writer, T objectToWrite, JsonSerializerOptions options)
+		{
+			if (writer is null)
+				throw new ArgumentNullException(nameof(writer));
+
+			TypeConverter converter = TypeDescriptor.GetConverter(objectToWrite);
+			string text = converter.ConvertToString(objectToWrite);
+			writer.WriteStringValue(text);
+		}
+
+		/// <inheritdoc/>
+		public override bool CanConvert(Type typeToConvert)
+		{
+			bool hasConverter = typeToConvert.GetCustomAttributes<TypeConverterAttribute>(inherit: true).Any();
+			return hasConverter;
+		}
+	}
+}

ClassLibraries/Macross.Json.Extensions/Code/System.Text.Json.Serialization/TypeConverterJsonAdapterFactory.cs

@@ -0,0 +1,26 @@
+using System.ComponentModel;
+using System.Linq;
+using System.Reflection;
+
+namespace System.Text.Json.Serialization
+{
+	/// <summary>
+	/// A factory used to create various <see cref="TypeConverterJsonAdapter{T}"/> instances.
+	/// </summary>
+	public class TypeConverterJsonAdapterFactory : JsonConverterFactory
+	{
+		/// <inheritdoc />
+		public override bool CanConvert(Type typeToConvert)
+		{
+			bool hasConverter = typeToConvert.GetCustomAttributes<TypeConverterAttribute>(inherit: true).Any();
+			return hasConverter;
+		}
+
+		/// <inheritdoc />
+		public override JsonConverter CreateConverter(Type typeToConvert, JsonSerializerOptions options)
+		{
+			Type converterType = typeof(TypeConverterJsonAdapter<>).MakeGenericType(typeToConvert);
+			return (JsonConverter)Activator.CreateInstance(converterType);
+		}
+	}
+}

ClassLibraries/Macross.Json.Extensions/Test/TypeConverterJsonAdapterFactoryTests.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Globalization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Text.RegularExpressions;
+
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace Macross.Json.Extensions.Tests
+{
+	[TestClass]
+	public class TypeConverterJsonAdapterFactoryTests
+	{
+		[TestMethod]
+		public void TypeConverterTest()
+		{
+			JsonSerializerOptions options = new JsonSerializerOptions
+			{
+				PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+			};
+			options.Converters.Add(new JsonStringEnumConverter());
+			options.Converters.Add(new TypeConverterJsonAdapterFactory());
+			options.IgnoreNullValues = true;
+			TestClass testObj = new TestClass()
+			{
+				One = new Coordinates { X = 10, Y = "str" },
+				Many = new List<Coordinates>
+				{
+					new Coordinates { X = 20, Y = "abc" }, new Coordinates { X = 30, Y = "zyx" },
+				}
+			};
+
+			string jsonExpected = "{\"one\":\"10,str\",\"many\":[\"20,abc\",\"30,zyx\"]}";
+			string json = JsonSerializer.Serialize(testObj, options);
+			Assert.AreEqual(jsonExpected, json);
+			TestClass? output = JsonSerializer.Deserialize<TestClass>(json, options);
+			Assert.IsNotNull(output);
+
+			Assert.AreEqual(testObj.One, output.One);
+			CollectionAssert.AreEqual(testObj.Many, output.Many);
+		}
+
+		private class TestClass
+		{
+			public Coordinates? One { get; set; }
+
+			public List<Coordinates>? Many { get; set; }
+		}
+
+		[TypeConverter(typeof(CoordinatesTypeConverter))]
+		private record Coordinates
+		{
+			public int X { get; set; }
+
+			public string? Y { get; set; }
+
+			public override string ToString() => $"{X},{Y}";
+		}
+
+#pragma warning disable CA1812 // Remove class never instantiated
+		private class CoordinatesTypeConverter : TypeConverter
+#pragma warning restore CA1812 // Remove class never instantiated
+		{
+			public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType) =>
+				sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
+
+			public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
+			{
+				if (value is string str)
+				{
+					Match match = Regex.Match(str, @"(\d+),(\w+)");
+					return new Coordinates { X = int.Parse(match.Groups[1].Value, CultureInfo.InvariantCulture), Y = match.Groups[2].Value };
+				}
+
+				return base.ConvertFrom(context, culture, value);
+			}
+		}
+	}
+}