Here's another way to be compatible with an IHttpActionResult return type. In this case I am asking it to use the XML Serializer(optional) instead of Data Contract serializer, I'm using return ResponseMessage(
so that I get a return compatible with IHttpActionResult:
return ResponseMessage(new HttpResponseMessage(HttpStatusCode.OK)
{
Content = new ObjectContent<SomeType>(objectToSerialize,
new System.Net.Http.Formatting.XmlMediaTypeFormatter {
UseXmlSerializer = true
})
});