I often see questions on the net about how to render a view to a string so it can be used somewhere.

My approach allows doing it without thinking about all the boilerplate code. Additionally not only the ViewResult can be rendered into a string but just about any type of the result. Here is example on how to return a JSON including the result of the view as additional information:

// Controller Action:
public JsonResult DoSomething() {
    var viewString = View("TheViewToRender").Capture(ControllerContext);
    return new JsonResult {
        JsonRequestBehavior = JsonRequestBehavior.AllowGet,
        Data = new {
            time = DateTime.Now,
            html = viewString
        }
    };
}

This can be done with 2 simple utility classes below. Just include them somewhere into your project.

    public class ResponseCapture : IDisposable {
        private readonly HttpResponseBase response;
        private readonly TextWriter originalWriter;
        private StringWriter localWriter;
        public ResponseCapture(HttpResponseBase response) {
            this.response = response;
            originalWriter = response.Output;
            localWriter = new StringWriter();
            response.Output = localWriter;
        }
        public override string ToString() {
            localWriter.Flush();
            return localWriter.ToString();
        }
        public void Dispose() {
            if (localWriter != null) {
                localWriter.Dispose();
                localWriter = null;
                response.Output = originalWriter;
            }
        }
    }
    public static class ActionResultExtensions {
        public static string Capture(this ActionResult result, ControllerContext controllerContext) {
            using (var it = new ResponseCapture(controllerContext.RequestContext.HttpContext.Response)) {
                result.ExecuteResult(controllerContext);
                return it.ToString();
            }
        }
    }

Enjoy and let me know if it works for you.