将 JSON 反序列化为子类

Question

我有 3 个课程：

class Person {
    public bool IsFemale { get; set; }
}

class Female : Person {
    public string FemaleSpecificProperty { get; set; }
}

class Male: Person { 
    public string MaleSpecificProperty { get; set; }
}

如何根据 Person.IsFemale 属性的值将给定的 JSON 字符串反序列化为特定实例（Female 或 Male）？ （预先我不知道使用了哪种确切类型，并且该属性是唯一的指示）

我曾考虑聘用 CustomCreationConverter<T>，但不知道如何在这里工作。

Answer 1

这是您的 person 类的转换器。它获取IsFemale 字段值，并基于它创建Female 或Male 人，由序列化程序填充：

public class PersonConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return typeof(Person).IsAssignableFrom(objectType);
    }

    public override object ReadJson(JsonReader reader, Type objectType,
        object existingValue, JsonSerializer serializer)
    {
        JObject jObject = JObject.Load(reader);
        var isFemale = (bool)jObject["IsFemale"];
        Person target = isFemale ? (Person)new Female() : new Male();
        serializer.Populate(jObject.CreateReader(), target);
        return target;
    }

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

用法：

List<Person> people = new List<Person>
{
    new Male { IsFemale = false, MaleSpecificProperty = "Y" },
    new Male { IsFemale = false, MaleSpecificProperty = "Y" },
    new Female { IsFemale = true, FemaleSpecificProperty = "X" }
};

string json = JsonConvert.SerializeObject(people);
var result = 
     JsonConvert.DeserializeObject<List<Person>>(json, new PersonConverter());

还可以看看 alex 提出的问题：How to implement custom JsonConverter