PushStreamContent Attachment Controller

        [HttpGet]
        public HttpResponseMessage Export(int id)
        {

            var response = Request.CreateResponse();

            response.Content = new PushStreamContent(
                async (outputStream, httpContent, transportContext) =>
                {
                    try
                    {
                        for (int page = 0; page < 10; page++)
                        {
                            string data = await GetData(id, page);
                            var buffer = Encoding.UTF8.GetBytes(data);
                            await outputStream.WriteAsync(buffer, 0, buffer.Length);

                        }
                    }
                    catch (HttpException ex)
                    {
                        if (ex.ErrorCode == -2147023667) // The remote host closed the connection. 
                        {
                            return;
                        }
                    }
                    finally
                    {
                        outputStream.Close();
                    }
                }, new MediaTypeHeaderValue("application/octet-stream"));
            response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
            {
                FileName = "myfile.csv"
            };
            return response;
        }