How to add global ASP.Net Web Api Filters

After asking this question, I finally found what I needed, so I am answering it.

I ran across this JsonpMediaTypeFormatter. Add it into the Application_Start of your global.asax by doing this:

var config = GlobalConfiguration.Configuration;
config.Formatters.Insert(0, new JsonpMediaTypeFormatter());

and you are good to go with an JQuery AJAX call that looks like this:

$.ajax({
    url: 'http://myurl.com',
    type: 'GET',
    dataType: 'jsonp',
    success: function (data) {
        alert(data.MyProperty);
    }
})

It seems to work very well.

This is the best way I have found to support extra GET methods and support the normal REST methods as well. Add the following routes to your WebApiConfig:

routes.MapHttpRoute("DefaultApiWithId", "Api/{controller}/{id}", new { id = RouteParameter.Optional }, new { id = @"\d+" });
routes.MapHttpRoute("DefaultApiWithAction", "Api/{controller}/{action}");
routes.MapHttpRoute("DefaultApiGet", "Api/{controller}", new { action = "Get" }, new { httpMethod = new HttpMethodConstraint(HttpMethod.Get) });
routes.MapHttpRoute("DefaultApiPost", "Api/{controller}", new {action = "Post"}, new {httpMethod = new HttpMethodConstraint(HttpMethod.Post)});

I verified this solution with the test class below. I was able to successfully hit each method in my controller below:

public class TestController : ApiController
{
    public string Get()
    {
        return string.Empty;
    }

    public string Get(int id)
    {
        return string.Empty;
    }

    public string GetAll()
    {
        return string.Empty;
    }

    public void Post([FromBody]string value)
    {
    }

    public void Put(int id, [FromBody]string value)
    {
    }

    public void Delete(int id)
    {
    }
}

I verified that it supports the following requests:

GET /Test
GET /Test/1
GET /Test/GetAll
POST /Test
PUT /Test/1
DELETE /Test/1

Note That if your extra GET actions do not begin with 'Get' you may want to add an HttpGet attribute to the method.