using System;

using System.Reflection;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

public class Program

{

    public static void Main()

    {

        Model model = new Model

        {

            id = 3,

            name = "john",

            userId = 101,

            color = "blue",

            alwaysExcluded = "shouldn't see this in JSON"

        };

​

        Console.WriteLine(SerializeForApiMethod(model, "method1"));

        Console.WriteLine(SerializeForApiMethod(model, "method2"));

        Console.WriteLine(SerializeForApiMethod(model, "method3"));

    }

    public static string SerializeForApiMethod(object model, string methodName)

    {

        Console.WriteLine($"--- {methodName} ---");

        var settings = new JsonSerializerSettings

        {

            ContractResolver = new SelectivePropertyResolver(methodName),

            Formatting = Formatting.Indented

        };

        return JsonConvert.SerializeObject(model, settings);

    }

}

​

public class Model

{

    [UseWithApiMethods("method1", "method3")]

    public int id { get; set; }

    [UseWithApiMethods("method1")]

    public string name { get; set; }

    [UseWithApiMethods("method2")]

    public int userId { get; set; }

    [UseWithApiMethods("method2")]

    public string color { get; set; }

    // This will be excluded because it has no [UseWithApiMethods] attribute

    public string alwaysExcluded { get; set; }

}

​

[AttributeUsage(AttributeTargets.Property)]

public class UseWithApiMethodsAttribute : Attribute

{

    public UseWithApiMethodsAttribute(params string[] methodNames)

    {

        MethodNames = methodNames;

    }

​

    public string[] MethodNames { get; private set; }

}

​

public class SelectivePropertyResolver : DefaultContractResolver

{

    public string ApiMethodName { get; private set; }

​

    public SelectivePropertyResolver(string apiMethodName)

    {

        ApiMethodName = apiMethodName;

    }

​

    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

    {

        JsonProperty prop = base.CreateProperty(member, memberSerialization);

        if (member.MemberType == MemberTypes.Property)

        {

            var att = ((PropertyInfo)member).GetCustomAttribute<UseWithApiMethodsAttribute>(true);

            if (att == null || !att.MethodNames.Contains(ApiMethodName))

            {

                prop.Ignored = true;

            }

        }

        return prop;

    }

}

​