How to change default Web API 2 to JSON formatter?

Question

I have a Web API project that returns some product data. It negotiates the return type correctly depending on the Accept header (JSON/XML) of the request. The problem is, if no Accept header is specified it returns XML, but I want it to return JSON by default

http://website.com/MyPage?type=json // returns json
http://website.com/MyPage?type=xml // returns xml
http://website.com/MyPage // returns xml by default

Here is my current code looks like:

GlobalConfiguration.Configuration.Formatters.XmlFormatter.MediaTypeMappings.Add(
new QueryStringMapping("type", "xml", new MediaTypeHeaderValue("application/xml")));

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

Answer 1

Add this in your App_Start/WebApiConfig.cs:

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

Answer 2

I think Web API just uses the first formatter it can find in the Formatters collection. You can change the ordering with something like

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

But it seems the JSON formatter should be the first one by default so you might want to check if you're already modifying this collection somewhere.