Unable to upload file using HTTP POST

Question

I'm trying to upload a file using HTTP Post but somehow there is no file to be found when I process the request on the server side. I was able to create a similar request and successfully upload file using Chrome's Postman extension, but somehow can't do the same programmatically.

Client code:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(fullUrl); 
request.Method = "POST"; 

using (Stream requestStream = request.GetRequestStream()) 
{
   string boundary = "----------" + DateTime.Now.Ticks.ToString("x");
   byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("--" + boundary + "\r\n");
   byte[] trailer = System.Text.Encoding.UTF8.GetBytes("\r\n--" + boundary + "\r\n");
   string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type:{2}\r\n\r\n";
   string header = string.Format(headerTemplate, "Files", "myFile.xml", "text/xml");
   byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
   requestStream.Write(boundarybytes, 0, boundarybytes.Length);
   requestStream.Write(headerbytes, 0, headerbytes.Length);                    
   requestStream.Write(uploadedFile, 0, uploadedFile.Length);
   requestStream.Write(trailer, 0, trailer.Length);

}

The request looks like this (in Fiddler) :

POST https://host/myUrl
Content-Length: 1067
Expect: 100-continue
Connection: Keep-Alive

------------8d2942f79ab208e
Content-Disposition: form-data; name="Files"; filename="myFile.xml"
Content-Type:text/xml

<myFile>
  Something
</myFile>

------------8d2942f79ab208e

Server side:

        var httpRequest = HttpContext.Current.Request;
        if (httpRequest.Files.Count != 1)
            return BadRequest("Didn't get the file.");

But I always get httpRequest.Files.Count to be zero. Why?

The following request (created using Postman) gives me httpRequest.Files.Count to be one, as expected.

POST myUrl HTTP/1.1
Host: host
Cache-Control: no-cache

----WebKitFormBoundaryE19zNvXGzXaLvS5C
Content-Disposition: form-data; name="Files"; filename="myFile.xml"
Content-Type: text/xml


----WebKitFormBoundaryE19zNvXGzXaLvS5C

What am I doing wrong?

NGambit · Accepted Answer · 2015-07-26 05:01:10Z

3

Figured it out. Thanks to this blog

Made two changes:

1) Added ContentType :

   request.ContentType = "multipart/form-data; boundary=" + boundary;

2) Modified how the boundary ends

byte[] trailer = System.Text.Encoding.UTF8.GetBytes("\r\n--" + boundary + "--");

And it works now. Hope this helps someone.

edited Jul 26, 2015 at 5:01

answered Jul 24, 2015 at 21:58

NGambit

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Comments

John Grabanski · Accepted Answer · 2015-07-24 20:30:56Z

0

Perhaps you need to set the request's content type to "multipart/form-data"

request.ContentType = "multipart/form-data";

answered Jul 24, 2015 at 20:30

John Grabanski

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2 Comments

NGambit Over a year ago

Tried that but it did not help.

John Grabanski Over a year ago

perhaps look into using WebClient.UploadFile and see if it'll work with your requirement

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