How to force ASP.NET Web API to always return JSON?

Question

ASP.NET Web API does content negotiation by default - will return XML or JSON or other type based on the Accept header. I don't need / want this, is there a way (like an attribute or something) to tell Web API to always return JSON?

You may be able to do this removing all formatters except json from GlobalConfiguration.Configuration.Formatters — Claudio Redi
– Claudio Redi, Commented Sep 27, 2012 at 20:05

christo8989 · Accepted Answer · 2016-03-15 22:19:45Z

174

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().

edited Mar 15, 2016 at 22:19

christo8989

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answered Sep 27, 2012 at 20:13

Filip W

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5 Comments

shashwat Over a year ago

and in which file..?? global.ascx..??

Jafin Over a year ago

In your Application_Start() method

Tien Do Over a year ago

Filip W just got better way now :), see it here strathweb.com/2013/06/…

Phill Over a year ago

@TienDo - linking to Filip's own blog?

Will Huang Over a year ago

The settings could be better put in App_Start\WebApiConfig.cs file.

Dmitry Pavlov · Accepted Answer · 2013-08-09 11:23:47Z

77

Supporting only JSON in ASP.NET Web API – THE RIGHT WAY

Replace IContentNegotiator with JsonContentNegotiator:

var jsonFormatter = new JsonMediaTypeFormatter();
//optional: set serializer settings here
config.Services.Replace(typeof(IContentNegotiator), new JsonContentNegotiator(jsonFormatter));

JsonContentNegotiator implementation:

public class JsonContentNegotiator : IContentNegotiator
{
    private readonly JsonMediaTypeFormatter _jsonFormatter;

    public JsonContentNegotiator(JsonMediaTypeFormatter formatter) 
    {
        _jsonFormatter = formatter;    
    }

    public ContentNegotiationResult Negotiate(
            Type type, 
            HttpRequestMessage request, 
            IEnumerable<MediaTypeFormatter> formatters)
    {
        return new ContentNegotiationResult(
            _jsonFormatter, 
            new MediaTypeHeaderValue("application/json"));
    }
}

answered Aug 9, 2013 at 11:23

Dmitry Pavlov

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5 Comments

BuddyJoe Over a year ago

where does the first part of the code get cut and pasted too? I don't see a "config" object in my Global.asax. Where is that variable coming from? the article doesn't explain either.

Dmitry Pavlov Over a year ago

Check public static void Register(HttpConfiguration config) { ... } method in WebApiConfig.cs file which has been gererated by VS2012 on project creation

Luke Puplett Over a year ago

Will this force JSON in the sense that a client Accepting XML will get JSON, and will not get a 406?

Luke Puplett Over a year ago

I can answer my own comment/question: it returns XML whatever the Accept header.

seangwright Over a year ago

This breaks my swashbuckle integration and it seems it is related to this issue on github ( github.com/domaindrivendev/Swashbuckle/issues/219 ). I'd like to use this method but the one below using GlobalConfiguration...Clear() actually works.

JJ_Coder4Hire · Accepted Answer · 2014-05-01 18:45:07Z

Philip W had the right answer but for clarity and a complete working solution, edit your Global.asax.cs file to look like this: (Notice I had to add the reference System.Net.Http.Formatting to the stock generated file)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http.Formatting;
using System.Web;
using System.Web.Http;
using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;

namespace BoomInteractive.TrainerCentral.Server {
    // Note: For instructions on enabling IIS6 or IIS7 classic mode, 
    // visit http://go.microsoft.com/?LinkId=9394801

    public class WebApiApplication : System.Web.HttpApplication {
        protected void Application_Start() {
            AreaRegistration.RegisterAllAreas();

            WebApiConfig.Register(GlobalConfiguration.Configuration);
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);

            //Force JSON responses on all requests
            GlobalConfiguration.Configuration.Formatters.Clear();
            GlobalConfiguration.Configuration.Formatters.Add(new JsonMediaTypeFormatter());
        }
    }
}

Bat_Programmer · Accepted Answer · 2016-01-17 00:00:51Z

11

GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();

This clears the XML formatter and thus defaulting to JSON format.

answered Jan 17, 2016 at 0:00

Bat_Programmer

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1 Comment

tfa Over a year ago

Perfect all that is needed

Luke Puplett · Accepted Answer · 2014-03-26 18:23:55Z

Inspired by Dmitry Pavlov's excellent answer, I altered it slightly so I could plug-in whatever formatter I wanted to enforce.

Credit to Dmitry.

/// <summary>
/// A ContentNegotiator implementation that does not negotiate. Inspired by the film Taken.
/// </summary>
internal sealed class LiamNeesonContentNegotiator : IContentNegotiator
{
    private readonly MediaTypeFormatter _formatter;
    private readonly string _mimeTypeId;

    public LiamNeesonContentNegotiator(MediaTypeFormatter formatter, string mimeTypeId)
    {
        if (formatter == null)
            throw new ArgumentNullException("formatter");

        if (String.IsNullOrWhiteSpace(mimeTypeId))
            throw new ArgumentException("Mime type identifier string is null or whitespace.");

        _formatter = formatter;
        _mimeTypeId = mimeTypeId.Trim();
    }

    public ContentNegotiationResult Negotiate(Type type, HttpRequestMessage request, IEnumerable<MediaTypeFormatter> formatters)
    {
        return new ContentNegotiationResult(_formatter, new MediaTypeHeaderValue(_mimeTypeId));
    }
}

Netferret · Accepted Answer · 2017-07-24 08:40:29Z

3

This has correct headers set. Seems a bit more elegant.

public JsonResult<string> TestMethod() 
{
return Json("your string or object");
}

answered Jul 24, 2017 at 8:40

Netferret

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2 Comments

Josh Withee Over a year ago

What are the fully qualified names for the JsonResult and Json classes?

Netferret Over a year ago

learn.microsoft.com/en-us/dotnet/api/…

durilka · Accepted Answer · 2013-10-30 14:11:24Z

If you want to do that for one method only, then declare your method as returning HttpResponseMessage instead of IEnumerable<Whatever> and do:

    public HttpResponseMessage GetAllWhatever()
    {
        return Request.CreateResponse(HttpStatusCode.OK, new List<Whatever>(), Configuration.Formatters.JsonFormatter);
    }

this code is pain for unit testing but that's also possible like this:

    sut = new WhateverController() { Configuration = new HttpConfiguration() };
    sut.Configuration.Formatters.Add(new Mock<JsonMediaTypeFormatter>().Object);
    sut.Request = new HttpRequestMessage();

If you want something for a method only create an msdn.microsoft.com/en-us/library/…

Carlo Saccone · Accepted Answer · 2018-09-26 11:10:41Z

for those using OWIN

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

becomes (in Startup.cs):

   public void Configuration(IAppBuilder app)
        {
            OwinConfiguration = new HttpConfiguration();
            ConfigureOAuth(app);

            OwinConfiguration.Formatters.Clear();
            OwinConfiguration.Formatters.Add(new DynamicJsonMediaTypeFormatter());

            [...]
        }

Antonio · Accepted Answer · 2017-04-12 08:26:41Z

0

Yo can use in WebApiConfig.cs:

config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));

answered Apr 12, 2017 at 8:26

Antonio

1

Comments

Ed_ · Accepted Answer · 2021-04-07 20:58:26Z

0

 public System.Web.Http.Results.JsonResult<MeineObjekt> Get()
    {
        return Json(new MeineObjekt()
        {
            Cod = "C4666",               
            Payment = 10.0m,
            isEnough = false
        });
    }

answered Apr 7, 2021 at 20:58

Ed_

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