从JSONCONVERTER运行默认序列化逻辑

Question

我有一个JsonConverter，它取决于特定标志，需要

• 运行自定义序列化逻辑
• 运行默认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

这是一个示例。说出您的班级以这样的序列化：

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

IsSpecial标志用于控制我们在转换器中做的事情还是让事情自然序列化。您可以像这样编写转换器：

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，请将其实例传递到SerializeObject方法（例如在设置中）。（请勿使用JsonConverter属性装饰目标类，否则将在序列化时导致无限的递归环。）

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"
  }
]

Answer 2

您可以更改CANWRITE属性以禁用自定义序列化器。如果物体可以包含相同类型的孩子或您在多个线程中序列化，则这将无法正常工作。

class FooConverter : JsonConverter
{
    bool _canWrite = true;
    public override bool CanWrite
    {
        get { return _canWrite;}
    }
    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
            _canWrite = false;
            jo = JObject.FromObject(foo);
            _canWrite = true;
        }
        jo.WriteTo(writer);
    }
}