Problems with downloading pdf file from web api service - asp.net

Question

I'm trying to set up a web api service that searches for a .pdf file in a directory and returns the file if it's found.
The controller
public class ProductsController : ApiController
{
[HttpPost]
public HttpResponseMessage Post([FromBody]string certificateId)
{
string fileName = certificateId + ".pdf";
var path = #"C:\Certificates\20487A" + fileName;
//check the directory for pdf matching the certid
if (File.Exists(path))
{
//if there is a match then return the file
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
var stream = new FileStream(path, FileMode.Open);
stream.Position = 0;
result.Content = new StreamContent(stream);
result.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment") { FileName = fileName };
result.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
result.Content.Headers.ContentDisposition.FileName = fileName;
return result;
}
else
{
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.Gone);
return result;
}
}
}
I'm calling the service with the following code
private void GetCertQueryResponse(string url, string serial)
{
string encodedParameters = "certificateId=" + serial.Replace(" ", "");
HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(url);
httpRequest.Method = "POST";
httpRequest.ContentType = "application/x-www-form-urlencoded";
httpRequest.AllowAutoRedirect = false;
byte[] bytedata = Encoding.UTF8.GetBytes(encodedParameters);
httpRequest.ContentLength = bytedata.Length;
Stream requestStream = httpRequest.GetRequestStream();
requestStream.Write(bytedata, 0, bytedata.Length);
requestStream.Close();
HttpWebResponse response = (HttpWebResponse)httpRequest.GetResponse();
if (response.StatusCode == HttpStatusCode.OK)
{
byte[] bytes = null;
using (Stream stream = response.GetResponseStream())
using (MemoryStream ms = new MemoryStream())
{
int count = 0;
do
{
byte[] buf = new byte[1024];
count = stream.Read(buf, 0, 1024);
ms.Write(buf, 0, count);
} while (stream.CanRead && count > 0);
ms.Position = 0;
bytes = ms.ToArray();
}
var filename = serial + ".pdf";
Response.ContentType = "application/pdf";
Response.Headers.Add("Content-Disposition", "attachment; filename=\"" + filename + "\"");
Response.BinaryWrite(bytes);
}
}
This appears to be working in the sense that the download file dialogue is shown with the correct file name and size etc, but the download takes only a couple of seconds (when the file sizes are >30mb) and the files are corrupt when I try to open them.
Any ideas what I'm doing wrong?

Answer 1

Your code looks similar to what Ive used in the past, but below is what I typically use:
Response.AddHeader("content-length", myfile.Length.ToString())
Response.AddHeader("content-disposition", "inline; filename=MyFilename")
Response.AddHeader("Expires", "0")
Response.AddHeader("Pragma", "Cache")
Response.AddHeader("Cache-Control", "private")
Response.ContentType = "application/pdf"
Response.BinaryWrite(finalForm)
I post this for 2 reasons. One, add the content-length header, you may have to indicate how large the file is so the application waits for the whole response.
If that doesn't fix it. Set a breakpoint, does the byte array content the appropriate length (aka, 30 million bytes for a 30 MB file)? Have you used fiddler to see how much content is coming back over the HTTP call?