Merge pull request #69 from dgg/feature/json-serialization

JSON serialization (plus EFCore)

NMoneys.sln

@@ -15,6 +15,10 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "archive", "archive", "{DB66
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NMoneys.Exchange", "archive\NMoneys.Exchange\NMoneys.Exchange.csproj", "{97C58515-92D8-4ECF-86B6-CFAABD66279D}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NMoneys.Serialization", "src\NMoneys.Serialization\NMoneys.Serialization.csproj", "{F61AA4C5-EAF0-425F-BF23-8B04DB85A1FF}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NMoneys.Serialization.Tests", "tests\NMoneys.Serialization.Tests\NMoneys.Serialization.Tests.csproj", "{A28BEBB8-EC70-4FC5-AFE7-9989F816347B}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -36,10 +40,20 @@ Global
 		{97C58515-92D8-4ECF-86B6-CFAABD66279D}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{97C58515-92D8-4ECF-86B6-CFAABD66279D}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{97C58515-92D8-4ECF-86B6-CFAABD66279D}.Release|Any CPU.Build.0 = Release|Any CPU
+		{F61AA4C5-EAF0-425F-BF23-8B04DB85A1FF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{F61AA4C5-EAF0-425F-BF23-8B04DB85A1FF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{F61AA4C5-EAF0-425F-BF23-8B04DB85A1FF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{F61AA4C5-EAF0-425F-BF23-8B04DB85A1FF}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A28BEBB8-EC70-4FC5-AFE7-9989F816347B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A28BEBB8-EC70-4FC5-AFE7-9989F816347B}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A28BEBB8-EC70-4FC5-AFE7-9989F816347B}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A28BEBB8-EC70-4FC5-AFE7-9989F816347B}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{0484566C-1D24-433E-90F2-B8B44BEF2FB2} = {558BFE88-EB25-4BFA-91B8-4CFF8696CED4}
 		{891B60F6-888D-488A-89D0-6E25FE1A7883} = {6454722E-5710-44B0-8EDE-1DE92929E641}
 		{97C58515-92D8-4ECF-86B6-CFAABD66279D} = {DB66F4E1-075E-4E1C-931E-5DD8F956E484}
+		{F61AA4C5-EAF0-425F-BF23-8B04DB85A1FF} = {6454722E-5710-44B0-8EDE-1DE92929E641}
+		{A28BEBB8-EC70-4FC5-AFE7-9989F816347B} = {558BFE88-EB25-4BFA-91B8-4CFF8696CED4}
 	EndGlobalSection
 EndGlobal

src/NMoneys.Serialization/BSON/MoneySerializer.cs

@@ -0,0 +1,101 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using MongoDB.Bson;
+using MongoDB.Bson.IO;
+using MongoDB.Bson.Serialization;
+using MongoDB.Bson.Serialization.Serializers;
+
+namespace NMoneys.Serialization.BSON;
+
+/// <summary>
+/// Allows customizing the serialization of monetary quantities
+/// </summary>
+public class MoneySerializer : StructSerializerBase<Money>
+{
+	// maps cannot be changed so the looked-up instance is cached
+	private readonly Lazy<BsonClassMap<Money>> _map = new(() =>
+		(BsonClassMap<Money>)BsonClassMap.LookupClassMap(typeof(Money)));
+
+	/// <inheritdoc />
+	public override void Serialize([NotNull]BsonSerializationContext context, BsonSerializationArgs args, Money value)
+	{
+		context.Writer.WriteStartDocument();
+
+		writeAmount(context.Writer, value);
+
+		writeCurrency(context, args, value);
+
+		context.Writer.WriteEndDocument();
+	}
+
+	/// <inheritdoc />
+	public override Money Deserialize([NotNull]BsonDeserializationContext context, BsonDeserializationArgs args)
+	{
+		context.Reader.ReadStartDocument();
+
+		decimal amount = readAmount(context.Reader);
+		CurrencyIsoCode currency = readCurrency(context, args);
+
+		context.Reader.ReadEndDocument();
+
+		var deserialized = new Money(amount, currency);
+		return deserialized;
+	}
+
+	#region write
+
+	private void writeAmount(IBsonWriter writer, Money value)
+	{
+		string amountName = _map.Value.GetMemberMap(m => m.Amount).ElementName;
+		writer.WriteName(amountName);
+		writer.WriteDecimal128(value.Amount);
+	}
+
+	private void writeCurrency(BsonSerializationContext context, BsonSerializationArgs args, Money value)
+	{
+		var currencyMap = _map.Value.GetMemberMap(c => c.CurrencyCode);
+		string currencyName = char.IsLower(currencyMap.ElementName, 0) ? "currency" : "Currency";
+		context.Writer.WriteName(currencyName);
+		currencyMap.GetSerializer().Serialize(context, args, value.CurrencyCode);
+	}
+
+	#endregion
+
+	#region read
+
+	private decimal readAmount(IBsonReader reader)
+	{
+		var amountMap = _map.Value.GetMemberMap(m => m.Amount);
+		reader.ReadName(amountMap.ElementName);
+		BsonType type = reader.GetCurrentBsonType();
+		decimal amount;
+		switch (type)
+		{
+			// does not support floating point conversion
+			case BsonType.String:
+				string str = reader.ReadString();
+				amount = decimal.Parse(str, CultureInfo.InvariantCulture);
+				break;
+			case BsonType.Decimal128:
+				Decimal128 dec  = reader.ReadDecimal128();
+				amount = Decimal128.ToDecimal(dec);
+				break;
+			default:
+				throw new NotSupportedException($"Cannot extract a monetary amount out of '{type.ToString()}'.");
+		}
+
+		return amount;
+	}
+
+	private CurrencyIsoCode readCurrency(BsonDeserializationContext context, BsonDeserializationArgs args)
+	{
+		var currencyMap = _map.Value.GetMemberMap(m => m.CurrencyCode);
+		string currencyName = char.IsLower(currencyMap.ElementName, 0) ? "currency" : "Currency";
+		context.Reader.ReadName(currencyName);
+		var currency = (CurrencyIsoCode)currencyMap.GetSerializer()
+			.Deserialize(context, args);
+		return currency;
+	}
+
+	#endregion
+}

src/NMoneys.Serialization/BSON/QuantitySerializer.cs

@@ -0,0 +1,23 @@
+using System.Diagnostics.CodeAnalysis;
+using MongoDB.Bson.Serialization;
+using MongoDB.Bson.Serialization.Serializers;
+
+namespace NMoneys.Serialization.BSON;
+
+public class QuantitySerializer : StructSerializerBase<Money>
+{
+	/// <inheritdoc />
+	public override void Serialize([NotNull]BsonSerializationContext context, BsonSerializationArgs args, Money value)
+	{
+		context.Writer.WriteString(value.AsQuantity());
+	}
+
+	/// <inheritdoc />
+	public override Money Deserialize([NotNull]BsonDeserializationContext context, BsonDeserializationArgs args)
+	{
+		string quantity = context.Reader.ReadString();
+
+		Money deserialized = Money.Parse(quantity);
+		return deserialized;
+	}
+}

src/NMoneys.Serialization/EFCore/JsonConverter.cs

@@ -0,0 +1,17 @@
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using System.Text.Json;
+
+namespace NMoneys.Serialization.EFCore;
+
+/// <summary>
+/// Defines conversions from an instance of <see cref="Money"/> in a model to a <see cref="string"/> in the store.
+/// </summary>
+public class JsonConverter : ValueConverter<Money, string>
+{
+	/// <summary>
+	/// Initializes a new instance of the <see cref="JsonConverter"/> class.
+	/// </summary>
+	public JsonConverter(JsonSerializerOptions options) : base(
+		m => JsonSerializer.Serialize(m, options),
+		str => JsonSerializer.Deserialize<Money>(str, options)) { }
+}

src/NMoneys.Serialization/EFCore/MoneyComparer.cs

@@ -0,0 +1,14 @@
+using Microsoft.EntityFrameworkCore.ChangeTracking;
+
+namespace NMoneys.Serialization.EFCore;
+
+/// <summary>
+/// Specifies custom value snapshotting and comparison for <see cref="Money"/>.
+/// </summary>
+public class MoneyComparer : ValueComparer<Money>
+{
+	/// <summary>
+	/// Creates a new <see cref="MoneyComparer"/>. A shallow copy will be used for the snapshot.
+	/// </summary>
+	public MoneyComparer() : base((x, y) => x.Equals(y), m => m.GetHashCode()) { }
+}

src/NMoneys.Serialization/EFCore/QuantityConverter.cs

@@ -0,0 +1,16 @@
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+namespace NMoneys.Serialization.EFCore;
+
+/// <summary>
+/// Defines conversions from an instance of <see cref="Money"/> in a model to a <see cref="string"/> in the store.
+/// </summary>
+public class QuantityConverter : ValueConverter<Money, string>
+{
+	/// <summary>
+	/// Initializes a new instance of the <see cref="QuantityConverter"/> class.
+	/// </summary>
+	public QuantityConverter() : base(
+		m => m.AsQuantity(),
+		str => Money.Parse(str)) { }
+}

src/NMoneys.Serialization/Json_NET/DescriptiveMoneyConverter.cs

@@ -0,0 +1,190 @@
+using System.Diagnostics.CodeAnalysis;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+
+namespace NMoneys.Serialization.Json_NET;
+
+/// <summary>
+/// Converts an monetary quantity <see cref="NMoneys.Money"/> to and from JSON.
+/// </summary>
+/// <remarks>
+/// <para>The serialized quantity would look something like: <c>{"Amount": 0, "Currency": "XXX"}</c>.</para>
+/// <para>Provides better JSON pointers for deserialization errors: better suited when not in control of serialization.</para>
+/// </remarks>
+public class DescriptiveMoneyConverter : JsonConverter<Money>
+{
+	private readonly bool _forceStringEnum;
+
+	/// <param name="forceStringEnum">Ignore enum value configuration and force string representation of the
+	/// <see cref="Money.CurrencyCode"/> when serializing.</param>
+	public DescriptiveMoneyConverter(bool forceStringEnum = false)
+	{
+		_forceStringEnum = forceStringEnum;
+	}
+
+	#region write
+
+	/// <inheritdoc />
+	public override void WriteJson([NotNull] JsonWriter writer, Money value, [NotNull] JsonSerializer serializer)
+	{
+		DefaultContractResolver? resolver = serializer.ContractResolver as DefaultContractResolver;
+
+		writer.WriteStartObject();
+
+		writeAmount(value.Amount, writer, resolver);
+		writeCurrency(value.CurrencyCode, writer, serializer, resolver);
+
+		writer.WriteEndObject();
+	}
+
+	private static void writeAmount(decimal amount, JsonWriter writer, DefaultContractResolver? resolver)
+	{
+		// non-pascal if "weird" resolver
+		string amountName = resolver?.GetResolvedPropertyName("Amount") ?? "amount";
+		writer.WritePropertyName(amountName);
+		writer.WriteValue(amount);
+	}
+
+	private void writeCurrency(CurrencyIsoCode currency,
+		JsonWriter writer, JsonSerializer serializer, DefaultContractResolver? resolver)
+	{
+		// non-pascal if "weird" resolver
+		string currencyName = resolver?.GetResolvedPropertyName("Currency") ?? "currency";
+		writer.WritePropertyName(currencyName);
+		if (_forceStringEnum)
+		{
+			// ignore configured enum value convention, string it is
+			writer.WriteValue(currency.ToString());
+		}
+		else
+		{
+			// follow configured enum value convention
+			serializer.Serialize(writer, currency, typeof(CurrencyIsoCode));
+		}
+	}
+
+	#endregion
+
+	#region read
+
+	/// <inheritdoc />
+	public override Money ReadJson([NotNull] JsonReader reader,
+		Type objectType, Money existingValue,
+		bool hasExistingValue, [NotNull] JsonSerializer serializer)
+	{
+		DefaultContractResolver? resolver = serializer.ContractResolver as DefaultContractResolver;
+
+		// no need to read StartObject token (already read)
+
+		decimal amount = readAmount(reader, resolver);
+		CurrencyIsoCode currency = readCurrency(reader, serializer, resolver);
+
+		// but EndObject needs to be read
+		readEndObject(reader);
+
+		return new Money(amount, currency);
+	}
+
+	private static decimal readAmount(JsonReader reader, DefaultContractResolver? resolver)
+	{
+		readProperty(reader);
+		ensurePropertyName("Amount", reader, resolver);
+		decimal amount = readAmountValue(reader);
+		return amount;
+	}
+
+	private static CurrencyIsoCode readCurrency(JsonReader reader, JsonSerializer serializer, DefaultContractResolver? resolver)
+	{
+		readProperty(reader);
+		ensurePropertyName("Currency", reader, resolver);
+		CurrencyIsoCode currency = readCurrencyValue(reader, serializer);
+		return currency;
+	}
+
+	private static void readEndObject(JsonReader reader)
+	{
+		bool read = reader.Read();
+		if (!read || reader.TokenType != JsonToken.EndObject)
+		{
+			throw buildException($"Expected token type '{JsonToken.EndObject}', but got '{reader.TokenType}'.", reader);
+		}
+	}
+
+	private static JsonSerializationException buildException(string message, JsonReader reader, Exception? inner = null)
+	{
+		IJsonLineInfo? info = reader as IJsonLineInfo;
+		JsonSerializationException exception = (info == null || info.HasLineInfo()) ?
+			new JsonSerializationException(message) :
+			new JsonSerializationException(message, reader.Path, info.LineNumber, info.LinePosition, inner);
+		return exception;
+	}
+
+
+	private static void readProperty(JsonReader reader)
+	{
+		bool isRead = reader.Read();
+		if (!isRead || reader.TokenType != JsonToken.PropertyName)
+		{
+			throw buildException($"Expected token type '{JsonToken.PropertyName}', but got '{reader.TokenType}'.", reader);
+		}
+	}
+
+	private static void ensurePropertyName(string pascalSingleName, JsonReader reader, DefaultContractResolver? resolver)
+	{
+#pragma warning disable CA1308
+		string propName = resolver?.GetResolvedPropertyName(pascalSingleName) ?? pascalSingleName.ToLowerInvariant();
+#pragma warning restore CA1308
+		bool matchAmount = StringComparer.Ordinal.Equals(reader.Value, propName);
+		if (!matchAmount)
+		{
+			throw buildException($"Expected property '{propName}', but got '{reader.Value}'.", reader);
+		}
+	}
+
+	private static decimal readAmountValue(JsonReader reader)
+	{
+		try
+		{
+			var amount = reader.ReadAsDecimal();
+			if (!amount.HasValue)
+			{
+				throw buildException("Amount should not be nullable.", reader);
+			}
+
+			return amount.Value;
+		}
+		catch (Exception ex)
+		{
+			throw buildException("Could not read amount value.", reader, ex);
+		}
+	}
+
+	private static CurrencyIsoCode readCurrencyValue(JsonReader reader, JsonSerializer serializer)
+	{
+		bool read = reader.Read();
+		if (!read)
+		{
+			throw buildException("Expected value token type.", reader);
+		}
+
+		CurrencyIsoCode currency = serializer.Deserialize<CurrencyIsoCode>(reader);
+		ensureDefined(currency, reader);
+
+		return currency;
+	}
+
+	private static void ensureDefined(CurrencyIsoCode maybeCurrency, JsonReader reader)
+	{
+		try
+		{
+			maybeCurrency.AssertDefined();
+		}
+		catch (Exception ex)
+		{
+			throw buildException($"Currency '{maybeCurrency}' not defined.", reader, ex);
+		}
+	}
+
+
+	#endregion
+}