Returning a downloadable file using a stream in asp.net web forms

Question

In asp.net MVC I can do something like the following which will open a stream:

 Stream strm1 = GenerateReport(Id);

return File(strm1, 
            "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
            "Report_" + reportId.ToString() + ".xlsx");

Notice how I am passing strm1 which is a stream. I can then name it Report_+ ...xlsx like the example above shows.

Is there a similar way to do this with asp.net web forms using c#.

Your problem isn't opening the stream, it's returning it as a downloadable file. — John Saunders, Jan 15 '15 at 23:08

Win · Accepted Answer · 2015-01-16T00:49:07.407

23

You can use TransmitFile or WriteFile if the file is in your website folder.

string fileName = string.Format("Report_{0}.xlsx", reportId);
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AddHeader("Content-Disposition", 
   string.Format("attachment; filename={0}", fileName));
Response.TransmitFile(fileName);
Response.End();

Stream

If your data is already in Memory, you want this method which writes the response in chunks.

Stream stm1 = GenerateReport(Id);
Int16 bufferSize = 1024;
byte[] buffer = new byte[bufferSize + 1];

Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AddHeader("Content-Disposition", 
    string.Format("attachment; filename=\"Report_{0}.xlsx\";", reportId));
Response.BufferOutput = false;
int count = stm1.Read(buffer, 0, bufferSize);

while (count > 0)
{
    Response.OutputStream.Write(buffer, 0, count);
    count = stm1.Read(buffer, 0, bufferSize);
}

edited Jan 16 '15 at 00:49

answered Jan 15 '15 at 23:15

Win

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Thank you. Where do I put the value of the stream at - strm1 as in my example – Nate Pet Jan 15 '15 at 23:26
What is the data type of strm1? Could you post the rest of your code? – Win Jan 15 '15 at 23:41
I uploaded the code. it is Stream stm1 = GenerateReport(Id); Thanks for your help – Nate Pet Jan 15 '15 at 23:42
I updated the code which let you write the response in chunks. – Win Jan 16 '15 at 00:05
Thanks. How do I specify the name of the file though. – Nate Pet Jan 16 '15 at 00:08
Make sure to add Response.End to the last example (lest the page's response will be added to the stream) – MC9000 Mar 14 '19 at 10:27

score 12 · Answer 2 · answered Nov 20 '15 at 01:31

I use this extension to send a stream as a downloadable file:

public static class ToDownloadExtention
{
   public static void ToDownload(this Stream stream, string fileName, HttpResponse response)
    {
        response.Clear();
        response.ContentType = "application/octet-stream";
        response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}", fileName));
        stream.CopyTo(response.OutputStream);
        response.End();
    }
}

And the usage is:

var stream = new MemoryStream();

stream.ToDownload("someFileName.ext",Response);

score 2 · Answer 3 · answered Jan 15 '15 at 23:22

Or if you have a stream ready to be written, simply copy it to response stream:

Response.Clear();
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AddHeader("Content-Disposition", "attachment; filename={your file name}");
Response.OutputStream.Write(stream, 0, stream.length);
Response.End();

Added same code just for visibility

Returning a downloadable file using a stream in asp.net web forms

3 Answers3

Stream

Linked

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