[asp.net-mvc] MVC: How to Return a String as JSON

All answers here provide good and working code. But someone would be dissatisfied that they all use ContentType as return type and not JsonResult.

Unfortunately JsonResult is using JavaScriptSerializer without option to disable it. The best way to get around this is to inherit JsonResult.

I copied most of the code from original JsonResult and created JsonStringResult class that returns passed string as application/json. Code for this class is below

public class JsonStringResult : JsonResult
    {
        public JsonStringResult(string data)
        {
            JsonRequestBehavior = JsonRequestBehavior.DenyGet;
            Data = data;
        }

        public override void ExecuteResult(ControllerContext context)
        {
            if (context == null)
            {
                throw new ArgumentNullException("context");
            }
            if (JsonRequestBehavior == JsonRequestBehavior.DenyGet &&
                String.Equals(context.HttpContext.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase))
            {
                throw new InvalidOperationException("Get request is not allowed!");
            }

            HttpResponseBase response = context.HttpContext.Response;

            if (!String.IsNullOrEmpty(ContentType))
            {
                response.ContentType = ContentType;
            }
            else
            {
                response.ContentType = "application/json";
            }
            if (ContentEncoding != null)
            {
                response.ContentEncoding = ContentEncoding;
            }
            if (Data != null)
            {
                response.Write(Data);
            }
        }
    }

Example usage:

var json = JsonConvert.SerializeObject(data);
return new JsonStringResult(json);