Capturing HTML output with a controller action filter

Question

I\'ve got the following filter in place on an action to capture the HTML output, convert it to a string, do some operations to modify the string, and return a ContentResult

Answer 1

I solved this by hijacking the HttpWriter, and having it write into a StringBuilder rather than the response, and then doing whatever needs to be done to/with the response before writing it to the output.

 private class UpdateFilter : ActionFilterAttribute
    {
        private HtmlTextWriter tw;
        private StringWriter sw;
        private StringBuilder sb;
        private HttpWriter output;

        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            sb = new StringBuilder();
            sw = new StringWriter(sb);
            tw = new HtmlTextWriter(sw);
            output = (HttpWriter)filterContext.RequestContext.HttpContext.Response.Output;
            filterContext.RequestContext.HttpContext.Response.Output = tw;
        }

        public override void OnResultExecuted(ResultExecutedContext filterContext)
        {
            string response = sb.ToString();
            //response processing
            output.Write(response);
        }
    }