ResultAsJsonAttribute.cs

ResultAsJsonAttribute.cs

using System.Web.Mvc;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;

namespace Whatever
{
    public class ResultAsJsonAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext context)
        {
            var result = context.ActionDescriptor.Execute(context, context.ActionParameters);

            context.Result = result is ActionResult actionResult
                ? actionResult
                : new JsonNetResult(result);
        }
    }

    public class JsonNetResult : ActionResult
    {
        private static readonly JsonSerializerSettings Settings = new JsonSerializerSettings
        {
            ContractResolver = new CamelCasePropertyNamesContractResolver(),
            DateTimeZoneHandling = DateTimeZoneHandling.Utc
        };

        private readonly object _data;

        public JsonNetResult(object data)
        {
            _data = data;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            var json = JsonConvert.SerializeObject(_data, Settings);
            var response = context.HttpContext.Response;
            response.ContentType = "application/json; charset=utf-8";
            response.Write(json);
        }
    }
}