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`JsonConvert.DeserializeObject <Model> (" {float: NaN} ")` fail

Newtonsoft Json.Net is obviously capable of deserializing NaN, but I cannot get it to do this in a floating point field. I get an exception Unexpected character "N".

In the following code:

using Newtonsoft.Json;

namespace TestNanDeserialize
{
    public class Number
    {
        public float Float;
    }

    public class Empty
    {
    }

    internal class Program
    {
        private const string testJson = "{float: NaN}";

        private static void Main(string[] args)
        {
            Succeeds();
            Fails();
        }

        private static void Succeeds()
        {
            var result = JsonConvert.DeserializeObject<Empty>(testJson);
        }

        private static void Fails()
        {
            var result = JsonConvert.DeserializeObject<Number>(testJson);
        }
    }
}

Succeeds()and Fails()create two very different call stacks:

Succeeds()

Newtonsoft.Json.dll!Newtonsoft.Json.JsonTextReader.ParseNumberNaN() Line 2299   C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonTextReader.ParseValue() Line 1572   C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonTextReader.Read() Line 381  C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(object newObject, Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, string id) Line 2331   C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, object existingValue) Line 485    C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, object existingValue) Line 291 C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(Newtonsoft.Json.JsonReader reader, System.Type objectType, bool checkAdditionalContent) Line 167 C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonSerializer.DeserializeInternal(Newtonsoft.Json.JsonReader reader, System.Type objectType) Line 823  C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonSerializer.Deserialize(Newtonsoft.Json.JsonReader reader, System.Type objectType) Line 802  C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonConvert.DeserializeObject(string value, System.Type type, Newtonsoft.Json.JsonSerializerSettings settings) Line 863 C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonConvert.DeserializeObject<TestNanDeserialize.Empty>(string value, Newtonsoft.Json.JsonSerializerSettings settings) Line 820 C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonConvert.DeserializeObject<TestNanDeserialize.Empty>(string value) Line 757  C#
TestNanDeserialize.exe!TestNanDeserialize.Program.Succeeds() Line 26    C#
TestNanDeserialize.exe!TestNanDeserialize.Program.Main(string[] args) Line 20   C#

Fails()

Newtonsoft.Json.dll!Newtonsoft.Json.JsonTextReader.ReadAsDouble() Line 948  C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadForType(Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonContract contract, bool hasConverter) Line 2214 C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.PopulateObject(object newObject, Newtonsoft.Json.JsonReader reader, Newtonsoft.Json.Serialization.JsonObjectContract contract, Newtonsoft.Json.Serialization.JsonProperty member, string id) Line 2359   C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, object existingValue) Line 485    C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(Newtonsoft.Json.JsonReader reader, System.Type objectType, Newtonsoft.Json.Serialization.JsonContract contract, Newtonsoft.Json.Serialization.JsonProperty member, Newtonsoft.Json.Serialization.JsonContainerContract containerContract, Newtonsoft.Json.Serialization.JsonProperty containerMember, object existingValue) Line 291 C#
Newtonsoft.Json.dll!Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(Newtonsoft.Json.JsonReader reader, System.Type objectType, bool checkAdditionalContent) Line 167 C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonSerializer.DeserializeInternal(Newtonsoft.Json.JsonReader reader, System.Type objectType) Line 823  C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonSerializer.Deserialize(Newtonsoft.Json.JsonReader reader, System.Type objectType) Line 802  C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonConvert.DeserializeObject(string value, System.Type type, Newtonsoft.Json.JsonSerializerSettings settings) Line 863 C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonConvert.DeserializeObject<TestNanDeserialize.Number>(string value, Newtonsoft.Json.JsonSerializerSettings settings) Line 820    C#
Newtonsoft.Json.dll!Newtonsoft.Json.JsonConvert.DeserializeObject<TestNanDeserialize.Number>(string value) Line 757 C#
TestNanDeserialize.exe!TestNanDeserialize.Program.Fails() Line 31   C#
TestNanDeserialize.exe!TestNanDeserialize.Program.Main(string[] args) Line 21   C#

You might think that this is enough to debug this, and maybe it should happen, but it really doesn't seem obvious to me which forks had to happen differently in all these layers to make it work.

EDIT: Yes, I know that unquoted NaN is not valid JSON. The declared Json.Net function is NaN support. Obviously, he is able to deserialize it, as the above code shows. However, I'm not sure if it can be deserialized in the float field.

. : https://github.com/JamesNK/Newtonsoft.Json/issues/908

+4
1

, JSON - , NaN. JSON Number:

{"float": "NaN"}

:

{float: NaN}

, FloatFormatHandling.Symbol, NaN , Json.NET NaN float double. , , . . NaN , JSON, Json.NET 5.0 1: NaN .

2

JSON {float: NaN} Json.NET:

  • 8.0.2 (): .
  • 7.0.1: .
  • 3.5: .

, . .

@shannon, Json.NET JSON. JToken.Parse("NaN") JValue float, JsonConvert.DeserializeObject<double>("NaN") . , NaN:

public class FloatNanConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return objectType == typeof(float) || objectType == typeof(float?);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        if (reader.TokenType == JsonToken.Null)
            return null;
        var value = JValue.Load(reader);
        if (objectType == typeof(float?))
            return (float?)value;
        else
            return (float)value;
    }

    public override bool CanWrite { get { false; } }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}
+3

Source: https://habr.com/ru/post/1626394/

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