Return JavaScript object literal, not JSON string, from ASP.NET MVC endpoint

Question

For various reasons, I have switched from ASP.NET MVC's built in JSON serializer (the one that returns a System.Web.Mvc.JsonResult object (see edit below)) to Newtonsoft. I didn't realize until after I began testing that the former returns a JavaScript object literal, while Newtonsoft returns a JSON formatted string.

I like not having to parse JSON strings on the client side — having it already as an object literal is very convenient — but I want to stick with Newtonsoft for other technical reasons.

For example, instead of seeing this result on my client...

"{"Errors":["Please enter a valid email address."],"HasErrors":true}"

...I'd like to see this result:

{"Errors":["Please enter a valid email address."],"HasErrors":true} // no quotes

Is there a way to make Newtonsoft return JS object literals instead of strings?

EDIT

The way my question was framed wasn't the best. There's nothing wrong with the JsonResult type. In fact, the solution still uses it. The only problem was the default Controller.Json methods, which can be overridden to use Newtonsoft (Json.NET) instead of the built-in serializer.

Answer 1

Just write a custom JsonResult that uses Newtonsoft serializer:

Something along the lines:

public abstract class BaseController : Controller
{
    protected override JsonResult Json(object data, string contentType, System.Text.Encoding contentEncoding)
    {
        return new JsonNetResult
        {
            ContentType = contentType,
            ContentEncoding = contentEncoding,
            Data = data
        };
    }

    protected override JsonResult Json(object data, string contentType, System.Text.Encoding contentEncoding, JsonRequestBehavior behavior)
    {
        return new JsonNetResult
                    {
                        ContentType = contentType,
                        ContentEncoding = contentEncoding,
                        Data = data,
                        JsonRequestBehavior = behavior
                    };
    }
}

JsonNetResult.cs:

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

public class JsonNetResult : JsonResult
{   
    public JsonSerializerSettings SerializerSettings { get; set; }
    public Formatting Formatting { get; set; }

    public JsonNetResult()
    {
        Formatting = Formatting.None;
        SerializerSettings = new JsonSerializerSettings();
        JsonRequestBehavior = JsonRequestBehavior.DenyGet;
    }

    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("This request has been blocked because sensitive information could be disclosed to third party web sites when this is used in a GET request. To allow GET requests, set JsonRequestBehavior to AllowGet.");
        }

        HttpResponseBase response = context.HttpContext.Response;

        response.ContentType = !string.IsNullOrEmpty(ContentType)
                                    ? ContentType
                                    : "application/json";

        if (ContentEncoding != null)
            response.ContentEncoding = ContentEncoding;

        if (Data != null)
        {
            var writer = new JsonTextWriter(response.Output) { Formatting = Formatting };

            var serializer = JsonSerializer.Create(SerializerSettings);
            serializer.Serialize(writer, Data);

            writer.Flush();
        }
    }
}

Credit: https://gist.github.com/jpoehls/1424538

Answer 2

Answer is here: How to force ASP.NET Web API to always return JSON?

Excerpt:

Clear all formatters and add Json formatter back.

GlobalConfiguration.Configuration.Formatters.Clear(); GlobalConfiguration.Configuration.Formatters.Add(new JsonMediaTypeFormatter()); EDIT

I added it to Global.asax inside Application_Start().