Download text as file in ASP.NET

Question

I am trying to download some text output from the screen as a text file. Following is the code. It's working on some pages and not working at all on other pages. Can anyone please suggest what's wrong here?

protected void Button18_Click(object sender, EventArgs e){
    Response.Clear();
    Response.Buffer = true;
    Response.ContentType = "text/plain";
    Response.AppendHeader("content-disposition", "attachment;filename=output.txt");

    StringBuilder sb = new StringBuilder();
    string output = "Output";
    sb.Append(output);
    sb.Append("\r\n");
    Response.Write(sb.ToString());
}

Could you solve someones problem if he would tell you that _"it's working on some pages and not working at all on other pages"_ without telling you what's not working? — Tim Schmelter, Feb 07 '13 at 15:57

score 31 · Accepted Answer · edited Mar 26 '18 at 13:39

31

As already mentioned by Joshua, you need to write the text to the output stream (Response). Also, don’t forget to invoke Response.End() after that.

protected void Button18_Click(object sender, EventArgs e)
{
    StringBuilder sb = new StringBuilder();
    string output = "Output";
    sb.Append(output);
    sb.Append("\r\n");

    string text = sb.ToString();

    Response.Clear();
    Response.ClearHeaders();

    Response.AppendHeader("Content-Length", text.Length.ToString());
    Response.ContentType = "text/plain";
    Response.AppendHeader("Content-Disposition", "attachment;filename=\"output.txt\"");

    Response.Write(text);
    Response.End();
}

Edit 1: added more details

Edit 2: I was reading other SO posts where users were recommending to put quotes around the filename:

Response.AppendHeader("content-disposition", "attachment;filename=\"output.txt\"");

Source: https://stackoverflow.com/a/12001019/558486

edited Mar 26 '18 at 13:39

Dennis T --Reinstate Monica--

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answered Feb 07 '13 at 16:03

Rui Jarimba

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Thanks for your response, it's still not working with the above code. The file download dialog is not being invoked. – Vijay Feb 07 '13 at 16:06
1

I would consider writing the data as binary as well. – Justin Feb 07 '13 at 16:06
2

@RuiJarimba The button is in an UpdatePanel, when I removed the updatepanel, it worked. – Vijay Feb 07 '13 at 16:24
this code works when used with `` but doesn't work with Button. Actually I am sending parameters with a URL so I have to use http get or post with button. Any idea? – Vishal_Kotecha Jul 24 '16 at 08:00
It's Write don't forget to use Response.End(); – Akshay Dattatray Nangare May 24 '17 at 09:21
if it doesn't work, you might need to handle your ScriptManager: https://stackoverflow.com/a/11221536/375422 – alansiqueira27 Oct 17 '18 at 18:25

Joshua · Answer 2 · 2013-02-07T16:08:38.780

4

If that's your actual code, you never write the text to the response stream, so the browser never receives any data.

At the very least, you should need

Response.Write(sb.ToString());

to write your text data to the response. Also, as an added bonus, if you know the length beforehand you should provide it using the Content-Length header so the browser can show the download progress.

You're also setting Response.Buffer = true; as part of your method but never explicitly flush the response to send it to the browser. Try adding a Response.Flush() after your write statement.

edited Feb 07 '13 at 16:08

answered Feb 07 '13 at 15:56

Joshua

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Sorry, forgot to include that line in the code above. It's still not working. Thanks. – Vijay Feb 07 '13 at 16:03
@Vj87 See my update, you're buffering so it might not be sending the content to the browser when you expect. Also, if this is a large amount of text, the entire file won't get sent to the browser until the server has buffered everything. You can also try setting `Response.Buffer` to false. – Joshua Feb 07 '13 at 16:09

Download text as file in ASP.NET

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