Newtonsoft Json 反序列化 1 json 属性为十进制或整数 c# 属性

Question

How to achieve below deserialization. value in JSON sometime int and sometime it's decimal . I am working under multiple restrictions so -

1. can't change value as int property. It may break existing contract and this is use all around system.
2. have to use MyType as this is use all around system

I noticed decimal in JSON to int deserialization will throw exception.

public class MyType
{
    [JsonProperty("type")]
    [Required]
    public string Type { get; set; }

    [JsonProperty("value")] // existing field 
    public int Value { get; set; }

    [JsonProperty("value")] // new field planning to add for new data
    public decimal Value2 { get; set; }
}

Answer 1

You could leverage a custom JsonConverter . Decorate your class:

[JsonConverter(typeof(CustomConverter))]
public class MyType
{
    [JsonProperty("type")]
    [Required]
    public string Type { get; set; }

    [JsonProperty("value")] // existing field 
    public int Value { get; set; }

    // new field planning to add for new data
    public decimal Value2 { get; set; }
}

Where CustomConverter is defined (roughly):

public class CustomConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        throw new NotImplementedException();
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        JObject jObject = JToken.Load(reader) as JObject;

        MyType myType = new MyType();
        myType.Type = jObject.GetValue("type").ToString();

        JToken tokenValue = jObject["value"];
        if (tokenValue.Type == JTokenType.Integer)
        {
            myType.Value = int.Parse(tokenValue.ToString());
        }
        else if (tokenValue.Type == JTokenType.Float) {
            myType.Value2 = decimal.Parse(tokenValue.ToString());
        }

        return myType;
    }

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

Note that one of Value and Value2 is implicitly set to 0 whereas the other property contains deserialized value.

To test the solution execute:

string json = @"{type:""Type1"",value: 27.99}";
MyType temp = JsonConvert.DeserializeObject<MyType>(json);