How do I get ASP.NET Web API to return JSON instead of XML using Chrome?

Answer 1

It's unclear to me why there is all of this complexity in the answer. Sure there are lots of ways you can do this, with QueryStrings, headers and options... but what I believe to be the best practice is simple. You request a plain URL (ex: http://yourstartup.com/api/cars) and in return you get JSON. You get JSON with the proper response header:

Content-Type: application/json

In looking for an answer to this very same question, I found this thread, and had to keep going because this accepted answer doesn't work exactly. I did find an answer which I feel is just too simple not to be the best one:

Set the default WebAPI formatter

I'll add my tip here as well.

WebApiConfig.cs

namespace com.yourstartup
{
  using ...;
  using System.Net.Http.Formatting;
  ...
  config.Formatters.Clear(); //because there are defaults of XML..
  config.Formatters.Add(new JsonMediaTypeFormatter());
}

I do have a question of where the defaults (at least the ones I am seeing) come from. Are they .NET defaults, or perhaps created somewhere else (by someone else on my project). Anways, hope this helps.

Answer 2

Just add those two line of code on your WebApiConfig class

public static class WebApiConfig
{
     public static void Register(HttpConfiguration config)
     {
          //add this two line 
          config.Formatters.Clear();
          config.Formatters.Add(new JsonMediaTypeFormatter());


          ............................
      }
}

Answer 3

I like Felipe Leusin's approach best - make sure browsers get JSON without compromising content negotiation from clients that actually want XML. The only missing piece for me was that the response headers still contained content-type: text/html. Why was that a problem? Because I use the JSON Formatter Chrome extension, which inspects content-type, and I don't get the pretty formatting I'm used to. I fixed that with a simple custom formatter that accepts text/html requests and returns application/json responses:

public class BrowserJsonFormatter : JsonMediaTypeFormatter
{
    public BrowserJsonFormatter() {
        this.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
        this.SerializerSettings.Formatting = Formatting.Indented;
    }

    public override void SetDefaultContentHeaders(Type type, HttpContentHeaders headers, MediaTypeHeaderValue mediaType) {
        base.SetDefaultContentHeaders(type, headers, mediaType);
        headers.ContentType = new MediaTypeHeaderValue("application/json");
    }
}

Register like so:

config.Formatters.Add(new BrowserJsonFormatter());

Answer 4

Most of the above answers makes perfect sense. Since you are seeing data being formatted in XML format ,that means XML formatter is applied,SO you can see JSON format just by removing the XMLFormatter from the HttpConfiguration parameter like

public static void Register(HttpConfiguration config)
        {
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );                
            config.Formatters.Remove(config.Formatters.XmlFormatter);                
            config.EnableSystemDiagnosticsTracing();
        }

since JSON is the default format

Answer 5

as per latest version of ASP.net WebApi 2,

under WebApiConfig.cs , this will work

config.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.XmlFormatter);
config.Formatters.Add(GlobalConfiguration.Configuration.Formatters.JsonFormatter);

Answer 6

Using Felipe Leusin's answer for years, after a recent update of core libraries and of Json.Net, I ran into a System.MissingMethodException:SupportedMediaTypes. The solution in my case, hopefully helpful to others experiencing the same unexpected exception, is to install System.Net.Http. NuGet apparently removes it in some circumstances. After a manual installation, the issue was resolved.