c# - 从 JsonConverter 运行默认序列化逻辑

Question

我有一个 JsonConverter，根据实例特定的标志，它需要要么

• 运行自定义序列化逻辑
• 运行默认的 Json.NET 序列化逻辑

如何从 JsonConverter 运行默认的 Json.NET 序列化逻辑？

谢谢

Answer 1

这是一个例子。假设您要序列化的类看起来像这样:

class Foo
{
    public bool IsSpecial { get; set; }
    public string A { get; set; }
    public string B { get; set; }
    public string C { get; set; }
}

IsSpecial 标志用于控制我们是在转换器中做一些特殊的事情还是让事情自然序列化。你可以这样写你的转换器:

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

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        Foo foo = (Foo)value;
        JObject jo;
        if (foo.IsSpecial)
        {
            // special serialization logic based on instance-specific flag
            jo = new JObject();
            jo.Add("names", string.Join(", ", new string[] { foo.A, foo.B, foo.C }));
        }
        else
        {
            // normal serialization
            jo = JObject.FromObject(foo);
        }
        jo.WriteTo(writer);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

然后，要使用转换器，将其实例传递给 SerializeObject 方法(例如在设置中)。 (不要用 JsonConverter 属性修饰目标类，否则序列化时会导致无限递归循环。)

class Program
{
    static void Main(string[] args)
    {
        List<Foo> foos = new List<Foo>
        {
            new Foo
            {
                A = "Moe",
                B = "Larry",
                C = "Curly",
                IsSpecial = false
            },
            new Foo
            {
                A = "Huey",
                B = "Dewey",
                C = "Louie",
                IsSpecial = true
            },
        };

        JsonSerializerSettings settings = new JsonSerializerSettings();
        settings.Converters.Add(new FooConverter());
        settings.Formatting = Formatting.Indented;

        string json = JsonConvert.SerializeObject(foos, settings);
        Console.WriteLine(json);
    }
}

输出:

[
  {
    "IsSpecial": false,
    "A": "Moe",
    "B": "Larry",
    "C": "Curly"
  },
  {
    "names": "Huey, Dewey, Louie"
  }
]