c# - 如何使用 Json.NET 以与对象相同的方式序列化 JObject？

Question

如何控制 JObject 到字符串的序列化？

我有一些返回 JObject 的 API，我通常会应用一些更改并保留或返回它们。我想避免保留空属性并应用一些额外的格式，但 JsonConvert 似乎完全忽略了我的设置。

这是问题的示例:

// startup.cs has the following
services.AddMvc().AddJsonOptions(o =>
{
    o.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;
});

public class SampleController : Controller
{
    JsonSerializerSettings _settings = new JsonSerializerSettings
    {
        NullValueHandling = NullValueHandling.Ignore
    };

    [HttpPost]
    [Route("object")]
    public object PostObject([FromBody] SomeObject data)
    {
        return JsonConvert.SerializeObject(data, _settings);
    }

    [HttpPost]
    [Route("jobject")]
    public object PostJObject([FromBody] JObject data)
    {
        return JsonConvert.SerializeObject(data, _settings);
    }

    public class SomeObject
    {
        public string Foo { get; set; }
        public string Bar { get; set; }
    }
}

发布 { "Foo": "Foo", "Bar": null }:

• /object 返回 {"Foo":"Foo"}
• /jobject 返回 {"Foo":"Foo","Bar":null}

我希望 JObject 方法返回与我使用对象相同的输出 json。如何在不创建助手的情况下实现这一目标？有没有办法使用相同的设置序列化 JObject？

Answer 1

与 NewtonSoft 框架良好集成的解决方案是提供一个遵循 NamingStrategy 的自定义 JObject 转换器。

JObject 自定义转换器

public class JObjectNamingStrategyConverter : JsonConverter<JObject> {

private NamingStrategy NamingStrategy { get; }

public JObjectNamingStrategyConverter (NamingStrategy strategy) {
    if (strategy == null) {
        throw new ArgumentNullException (nameof (strategy));
    }
    NamingStrategy = strategy;
}

public override void WriteJson (JsonWriter writer, JObject value, JsonSerializer serializer) {
    writer.WriteStartObject ();
    foreach (JProperty property in value.Properties ()) {
        var name = NamingStrategy.GetPropertyName (property.Name, false);
        writer.WritePropertyName (name);
        serializer.Serialize (writer, property.Value);
    }
    writer.WriteEndObject ();
}

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

用法

var snakeNameStrategy = new SnakeCaseNamingStrategy ();
var jsonSnakeSettings = new JsonSerializerSettings {
Formatting = Formatting.Indented,
Converters = new [] { new JObjectNamingStrategyConverter (snakeNameStrategy) },
   ContractResolver = new DefaultContractResolver {
       NamingStrategy = snakeNameStrategy
   },
};

var json = JsonConvert.SerializeObject (obj, jsonSnakeSettings);

您可以在 GitHub 上找到有效的 PoC .