将字符串字段反序列化为属性对象

问题描述

假设我有一个MyClass类型的对象，该对象按如下方式序列化为Json：

{"DurationField":"3 Months",*OtherProperties*}

我想将此Json反序列化为以下类：

public class MyClass{
  *OTHER PROPERTIES*

  public Duration DurationField{ get; set;}
}

public class Duration{
  public Duration()

  // Constructor that takes a string,parses it and sets Units and N
  public Duration(string strValue){
  Duration duration = Duration.Parse(strValue)
  N = duration.N;
  Units = duration.Units;
}

  // private method that takes a string and returns a Duration
  private Duration Parse(string str){
   ...
}

  // Enum field to represent units of time,like day/month/year
  public TimeUnits Units{ get; set;}

  // Number of units of time
  public int N{ get; set;}

}

我试图实现一个自定义的JsonConverter（如下），只是意识到它只能在“ DurationField”的子节点上工作，这意味着我必须使其序列化为“ DurationField”：{“ Value “：” 3个月“}或类似的内容。

public sealed class DurationConverter : JsonConverter<Duration>
  {
    public override bool CanConvert(Type objectType)
    {
      return (objectType == typeof(Duration));
    }

    public override Duration Read(ref Utf8JsonReader reader,Type typeToConvert,JsonSerializerOptions options)
    {
      // Load the JSON for the Result into a JObject
      JObject jo = JObject.Parse(reader.GetString());

      // Read the properties which will be used as constructor parameters
      string durationString = (string)jo["DurationField"];

      // Construct the Result object using the non-default constructor
      Duration result = new Duration(tenorString);

      // (If anything else needs to be populated on the result object,do that here)

      // Return the result
      return result;
    }


    public override void Write(Utf8JsonWriter writer,Duration value,JsonSerializerOptions options)
    {
      JsonSerializer.Serialize(writer,value,options);
    }
  }

有什么办法解决吗？即，使Custom转换器将字符串作为输入，并在解析字符串后将其转换为对象？我能想到的最接近的东西是JsonStringEnumConverter，它接受一个字符串并将其转换为Enum。

解决方法

我知道这不是您要的，但是解决这个问题的一种方法可能是：

public class MyClass{
  *OTHER PROPERTIES*

  public string DurationField { get; set;}
  private Duration _duration = null;

  [JsonIgnore]
  public Duration Duration {
    get {
      if (_duration == null) {
        _duration = new Duration(this.DurationField);
      }

      return _duration;
    }
  }
}

在无法正确解析等情况下，您可以保留原始的字符串值，但还可以访问Duration。