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

Answer 1

In the WebApiConfig.cs, add to the end of the Register function:

// Remove the XML formatter
config.Formatters.Remove(config.Formatters.XmlFormatter);

Source.

Answer 2

As the question is Chrome-specific, you can get the Postman extension which allows you to set the request content type.

Answer 3

One quick option is to use the MediaTypeMapping specialization. Here is an example of using QueryStringMapping in the Application_Start event:

GlobalConfiguration.Configuration.Formatters.JsonFormatter.MediaTypeMappings.Add(new QueryStringMapping("a", "b", "application/json"));

Now whenever the url contains the querystring ?a=b in this case, Json response will be shown in the browser.

Answer 4

Here is a solution similar to jayson.centeno's and other answers, but using the built-in extension from System.Net.Http.Formatting.

public static void Register(HttpConfiguration config)
{
    // add support for the 'format' query param
    // cref: http://blogs.msdn.com/b/hongyes/archive/2012/09/02/support-format-in-asp-net-web-api.aspx
    config.Formatters.JsonFormatter.AddQueryStringMapping("$format", "json", "application/json");
    config.Formatters.XmlFormatter.AddQueryStringMapping("$format", "xml", "application/xml");

    // ... additional configuration
 }

The solution was primarily geared toward supporting $format for OData in the early releases of WebApi, but it also applies to the non-OData implementation, and returns the Content-Type: application/json; charset=utf-8 header in the response.

It allows you to tack &$format=json or &$format=xml to the end of your uri when testing with a browser. It does not interfere with other expected behavior when using a non-browser client where you can set your own headers.

Answer 5

In the Global.asax I am using the code below. My URI to get JSON is http://www.digantakumar.com/api/values?json=true

protected void Application_Start()
{
    AreaRegistration.RegisterAllAreas();

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

    GlobalConfiguration.Configuration.Formatters.JsonFormatter.MediaTypeMappings.Add(new  QueryStringMapping("json", "true", "application/json"));
}

Answer 6

Some time has passed since this question was asked (and answered) but another option is to override the Accept header on the server during request processing using a MessageHandler as below:

public class ForceableContentTypeDelegationHandler : DelegatingHandler
{
    protected async override Task<HttpResponseMessage> SendAsync(
                HttpRequestMessage request,
                CancellationToken cancellationToken)
    {
        var someOtherCondition = false;
        var accHeader = request.Headers.GetValues("Accept").FirstOrDefault();
        if (someOtherCondition && accHeader.Contains("application/xml"))
        {
            request.Headers.Remove("Accept");
            request.Headers.Add("Accept", "application/json");
        }
        return await base.SendAsync(request, cancellationToken);
    }
}

Where someOtherCondition can be anything including browser type, etc. This would be for conditional cases where only sometimes do we want to override the default content negotiation. Otherwise as per other answers, you would simply remove an unnecessary formatter from the configuration.

You'll need to register it of course. You can either do this globally:

  public static void Register(HttpConfiguration config) {
      config.MessageHandlers.Add(new ForceableContentTypeDelegationHandler());
  }

or on a route by route basis:

config.Routes.MapHttpRoute(
   name: "SpecialContentRoute",
   routeTemplate: "api/someUrlThatNeedsSpecialTreatment/{id}",
   defaults: new { controller = "SpecialTreatment" id = RouteParameter.Optional },
   constraints: null,
   handler: new ForceableContentTypeDelegationHandler()
);

And since this is a message handler it will run on both the request and response ends of the pipeline much like an HttpModule. So you could easily acknowledge the override with a custom header:

public class ForceableContentTypeDelegationHandler : DelegatingHandler
{
    protected async override Task<HttpResponseMessage> SendAsync(
                HttpRequestMessage request,
                CancellationToken cancellationToken)
    {
        var wasForced = false;
        var someOtherCondition = false;
        var accHeader = request.Headers.GetValues("Accept").FirstOrDefault();
        if (someOtherCondition && accHeader.Contains("application/xml"))
        {
            request.Headers.Remove("Accept");
            request.Headers.Add("Accept", "application/json");
            wasForced = true;
        }

        var response =  await base.SendAsync(request, cancellationToken);
        if (wasForced){
          response.Headers.Add("X-ForcedContent", "We overrode your content prefs, sorry");
        }
        return response;
    }
}