c# - 在反序列化期间解析 JSON 属性

Question

使用 JSON 的以下部分:

"tags": 
{
  "tiger:maxspeed": "65 mph"
}

我有相应的 C# 类用于反序列化:

public class Tags
{

    [JsonProperty("tiger:maxspeed")]
    public string Maxspeed { get; set; }

}

我想将它反序列化为一个整数属性:

public class Tags
{

    [JsonProperty("tiger:maxspeed")]
    public int Maxspeed { get; set; }

}

是否可以在反序列化过程中将字符串的数字部分从 JSON 解析为 int？

我想我想要这样的东西:

public class Tags
{
    [JsonProperty("tiger:maxspeed")]
    public int Maxspeed 
    {
        get
        {
            return _maxspeed;
        }
        set
        {
            _maxspeed = Maxspeed.Parse(<incoming string>.split(" ")[0]);
        }
    }
}

Answer 1

我会建议@djv 想法的变体。将字符串属性设为私有(private)并将转换逻辑放在那里。由于 [JsonProperty] 属性，序列化程序将拾取它，但它不会混淆类的公共(public)接口(interface)。

public class Tags
{
    [JsonIgnore]
    public int MaxSpeed { get; set; }

    [JsonProperty("tiger:maxspeed")]
    private string MaxSpeedString
    {
        get { return MaxSpeed + " mph"; }
        set 
        {
            if (value != null && int.TryParse(value.Split(' ')[0], out int speed))
                MaxSpeed = speed;
            else
                MaxSpeed = 0;
        }
    }
}

fiddle :https://dotnetfiddle.net/SR9xJ9

或者，您可以使用自定义 JsonConverter 将转换逻辑与模型类分开:

public class Tags
{
    [JsonProperty("tiger:maxspeed")]
    [JsonConverter(typeof(MaxSpeedConverter))]
    public int MaxSpeed { get; set; }
}

class MaxSpeedConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        // CanConvert is not called when the converter is used with a [JsonConverter] attribute
        return false;   
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        string val = (string)reader.Value;

        int speed;
        if (val != null && int.TryParse(val.Split(' ')[0], out speed))
            return speed;

        return 0;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        writer.WriteValue((int)value + " mph");
    }
}

fiddle :https://dotnetfiddle.net/giCDZW