FileUpload to FileStream

Question

I am in process of sending the file along with HttpWebRequest. My file will be from FileUpload UI. Here I need to convert the File Upload to filestream to send the stream along with HttpWebRequest. How do I convert the FileUpload to a filestream?

I need to transfer file from one domain to another. so get the uploaded file and send it using HttpWebRequest — Gopi, Jun 21 '10 at 10:31

score 28 · Accepted Answer · answered Jun 21 '10 at 06:25

Since FileUpload.PostedFile.InputStream gives me Stream, I used the following code to convert it to byte array

public static byte[] ReadFully(Stream input)
{
    byte[] buffer = new byte[input.Length];
    //byte[] buffer = new byte[16 * 1024];
    using (MemoryStream ms = new MemoryStream())
    {
        int read;
        while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
        {
            ms.Write(buffer, 0, read);
        }
        return ms.ToArray();
    }
}

score 13 · Answer 2 · answered Jul 09 '10 at 17:57

Might be better to pipe the input stream directly to the output stream:

inputStream.CopyTo(outputStream);

This way, you are not caching the entire file in memory before re-transmission. For example, here is how you would write it to a FileStream:

FileUpload fu;  // Get the FileUpload object.
using (FileStream fs = File.OpenWrite("file.dat"))
{
    fu.PostedFile.InputStream.CopyTo(fs);
    fs.Flush();
}

If you wanted to write it directly to another web request, you could do the following:

FileUpload fu; // Get the FileUpload object for the current connection here.
HttpWebRequest hr;  // Set up your outgoing connection here.
using (Stream s = hr.GetRequestStream())
{
    fu.PostedFile.InputStream.CopyTo(s);
    s.Flush();
}

That will be more efficient, as you will be directly streaming the input file to the destination host, without first caching in memory or on disk.

Once you access PostedFile, the file has already completely been buffered by ASP.NET. This can only be circumvented by using `HttpRequest.GetBufferlessInputStream()` (.NET 4 or higher), but that in turn requires you to parse the entire request body yourself. — ErikHeemskerk, Mar 28 '12 at 20:23

score 3 · Answer 3 · answered Jun 18 '10 at 08:57

3

You can't convert a FileUpload into a FileStream. You can, however, get a MemoryStream from that FileUpload's PostedFile property. You can then use that MemoryStream to fill your HttpWebRequest.

answered Jun 18 '10 at 08:57

ErikHeemskerk

1,623
14
30

2

Could you please elaborate - possibly with a code example or link? – PeterX Sep 20 '13 at 06:41
@PeterX: See Extremeswank's answer for an example. – ErikHeemskerk Sep 23 '13 at 09:18

score 3 · Answer 4 · answered Mar 31 '17 at 12:35

You can put a FileUpload file directly into a MemoryStream by using FileBytes (simplified answer from Tech Jerk)

using (MemoryStream ms = new MemoryStream(FileUpload1.FileBytes))
{
    //do stuff 
}

Or if you do not need a memoryStream

byte[] bin = FileUpload1.FileBytes;

FileUpload to FileStream

4 Answers4

Linked