Amount used decimal precision to serialize to JSON

specs/Qowaiv.Specs/Financial/Amount_specs.cs

@@ -120,16 +120,24 @@ public void System_Text_JSON_deserialization_min_value()
             amount.Should().Be(Amount.MinValue);
         }
 
-        [Test]
-        public void System_Text_JSON_deserialization_max_value()
+        [TestCase("7.922816251426434E+28")]
+        [TestCase("79228162514264337593543950335")]
+        public void System_Text_JSON_deserialization_max_value(string json)
         {
-            var amount = System.Text.Json.JsonSerializer.Deserialize<Amount>("7.922816251426434E+28");
+            var amount = System.Text.Json.JsonSerializer.Deserialize<Amount>(json);
             amount.Should().Be(Amount.MaxValue);
         }
 
         [TestCase(1234.56, 1234.56)]
         public void System_Text_JSON_serialization(Amount svo, object json)
             => JsonTester.Write_System_Text_JSON(svo).Should().Be(json);
+
+        [Test]
+        public void System_Text_JSON_serialization_Max_value()
+        {
+           var json = System.Text.Json.JsonSerializer.Serialize(Amount.MaxValue);
+            json.Should().Be("79228162514264337593543950335");
+        }
 #endif
         [TestCase("1234.56", 1234.56)]
         [TestCase(1234.56, 1234.56)]
@@ -141,6 +149,10 @@ public void convention_based_deserialization(object json, Amount svo)
         public void convention_based_serialization(Amount svo, object json)
             => JsonTester.Write(svo).Should().Be(json);
 
+        [Test]
+        public void convention_based_serialization_max_value()
+            => JsonTester.Write(Amount.MaxValue).Should().Be(79228162514264337593543950335M);
+
         [TestCase("Invalid input", typeof(FormatException))]
         [TestCase("2017-06-11", typeof(FormatException))]
         public void throws_for_invalid_json(object json, Type exceptionType)

src/Qowaiv/Financial/Amount.cs

@@ -130,7 +130,7 @@ namespace Qowaiv.Financial;
     /// enough to have a <see cref="string"/> representation of -0.
     /// </remarks>
     [Pure]
-    public double ToJson() => (double)m_Value;
+    public decimal ToJson() => m_Value;
 
     /// <summary>Returns a <see cref="string"/> that represents the current Amount for debug purposes.</summary>
     [DebuggerBrowsable(DebuggerBrowsableState.Never)]
@@ -147,6 +147,16 @@ public string ToString(string? format, IFormatProvider? formatProvider)
     [Pure]
     private string ToXmlString() => ToString(CultureInfo.InvariantCulture);
 
+    /// <summary>Deserializes the amount from a JSON number.</summary>
+    /// <param name="json">
+    /// The JSON number to deserialize.
+    /// </param>
+    /// <returns>
+    /// The deserialized amount.
+    /// </returns>
+    [Pure]
+    public static Amount FromJson(decimal json) => new(json);
+
     /// <summary>Deserializes the amount from a JSON number.</summary>
     /// <param name="json">
     /// The JSON number to deserialize.

src/Qowaiv/Json/Financial/AmountJsonConverter.cs

@@ -16,6 +16,10 @@ public class AmountJsonConverter : SvoJsonConverter<Amount>
     [Pure]
     protected override Amount FromJson(long json) => Amount.FromJson(json);
 
+    /// <inheritdoc />
+    [Pure]
+    protected override Amount FromJson(decimal json) => Amount.FromJson(json);
+
     /// <inheritdoc />
     [Pure]
     protected override Amount FromJson(double json) => Amount.FromJson(json);

src/Qowaiv/Json/Mathematics/FractionJsonConverter.cs

@@ -16,6 +16,10 @@ public class FractionJsonConverter : SvoJsonConverter<Fraction>
     [Pure]
     protected override Fraction FromJson(long json) => Fraction.FromJson(json);
 
+    /// <inheritdoc />
+    [Pure]
+    protected override Fraction FromJson(decimal json) => Fraction.FromJson(json);
+
     /// <inheritdoc />
     [Pure]
     protected override Fraction FromJson(double json) => Fraction.FromJson(json);

src/Qowaiv/Json/SvoJsonConverter.cs

@@ -109,6 +109,10 @@ public override void WriteAsPropertyName(Utf8JsonWriter writer, TSvo value, Json
     [Pure]
     protected virtual TSvo FromJson(long json) => FromJson(json.ToString(CultureInfo.InvariantCulture));
 
+    /// <summary>Creates the SVO based on its JSON (decimal) number representation.</summary>
+    [Pure]
+    protected virtual TSvo FromJson(decimal json) => FromJson((double)json);
+
     /// <summary>Creates the SVO based on its JSON (double) number representation.</summary>
     [Pure]
     protected virtual TSvo FromJson(double json) => FromJson(json.ToString(CultureInfo.InvariantCulture));
@@ -123,10 +127,14 @@ private TSvo ReadNumber(ref Utf8JsonReader reader)
         {
             return FromJson(num);
         }
-        else if (reader.TryGetDouble(out double dec))
+        else if (reader.TryGetDecimal(out decimal dec))
         {
             return FromJson(dec);
         }
+        else if (reader.TryGetDouble(out double dbl))
+        {
+            return FromJson(dbl);
+        }
         else throw new JsonException($"QowaivJsonConverter does not support writing from {reader.GetString()}.");
     }
 }

src/Qowaiv/Mathematics/Fraction.cs

@@ -325,6 +325,16 @@ void ISerializable.GetObjectData(SerializationInfo info, StreamingContext contex
     [Pure]
     public string ToJson() => ToString(CultureInfo.InvariantCulture);
 
+    /// <summary>Deserializes the fraction from a JSON number.</summary>
+    /// <param name = "json">
+    /// The JSON number to deserialize.
+    /// </param>
+    /// <returns>
+    /// The deserialized fraction.
+    /// </returns>
+    [Pure]
+    public static Fraction FromJson(decimal json) => Cast(json);
+
     /// <summary>Deserializes the fraction from a JSON number.</summary>
     /// <param name = "json">
     /// The JSON number to deserialize.