Change WCF WebApi HttpContent response

Using the WCF Web API how would I go about changing a response's content body after the application logic has been run but before it's returned to the user. The goal is if suppressstatuscontent is true we:

Add a statuscode field to the content body
Change the statuscode on the response to 200

I have overridden a DelegatingChannel and in the SendAsnyc have some code that looks like this:

protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
   return base.SendAsync(request, cancellationToken).ContinueWith<HttpResponseMessage>(task =>
   {
      var response = task.Result;

      if (CheckIfRequestHadSuppressStatusCode(request) == true)
      {
         string newResponse = (response.Content == null) ? "" : response.Content.ReadAsString();
         newResponse = "<body>" +newResponse + "</body><statuscode>" + response.StatusCode + "</statuscode>";
         response.StatusCode = HttpStatusCode.OK;                                 
      }
      return response;
   });

A major problem is this doesn't handle BOTH, xml and Json. I feel like there must be a much better way to go about the problem as this feels very hacky.

Solution

I'm not sure of the right approach but I would try something like this:

protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
   return base.SendAsync(request, cancellationToken)
      .ContinueWith<HttpResponseMessage>(task =>
      {
         var response = task.Result;
         if (CheckIfRequestHadSuppressStatusCode(request) == true)
         {
            switch(response.Content.Headers.ContentType.MediaType)
            {
               case "application/xml":
                  response.Content = new XmlWithStatusContent(response.Content)
                  break;
               case "application/json":
                  response.Content = new JsonWithStatusContent(response.Content)
                  break;
            }

            response.StatusCode = HttpStatusCode.OK;                                 
         }
         
         return response;
      });
}

You can encapsulate the code that adds the extra status code markup in specialized versions of HttpContent (e.g. XmlWithStatusContent and JsonWithStatusContent).