Responding with a csv file in asp.net

Question

I am trying to make a csv file from a textbox and then send it to the user. This is my code so far:

Response.Clear();
            Response.ContentType = "text/csv";
            Response.AppendHeader("Content-Disposition",
                string.Format("attachment; filename={0}", DateTime.Now));

            Response.Write(TextBox_Data.Text);
            Context.Response.End();

What is sent is an empty xml file, I have never tried responding with a file before and I'm wondering why it does this?

I have also tried the following which did not work:

var writer = File.CreateText("C:\\file.csv");
            writer.WriteLine(TextBox_Data.Text);

            Context.Response.Clear();
            Context.Response.AppendHeader("content-disposition", "attachment; filename=" + DateTime.Now + ".csv");
            Context.Response.ContentType = "text/csv";
            Context.Response.Write("C:\\file.csv");
            Context.Response.Flush();
            Context.Response.End();

Let me know if you have the answer :)

You are trying to create a CSV file from what a user puts in a text box, and then email it to the user, or have the user automatically download it? Can you give us a little more context for the how and why beyond this code? — Jennifer S
– Jennifer S, Commented Sep 14, 2011 at 14:00
Try writing to a different path. Perhaps to your profile path. Writing to your root is dangerous. — C0L.PAN1C
– C0L.PAN1C, Commented Sep 14, 2011 at 14:09
Indeed, I am trying to make a downloadable CSV file from a multiline textbox :) Actually I don't care about putting the file on my drive, I just want a downloadable CSV file, with the text from the textbox. — Peter Rasmussen
– Peter Rasmussen, Commented Sep 14, 2011 at 14:30
Writing to the root is not only dangerous, but unless you have explicitly given permission to your app pool identity to do so, it will fail for security reasons — ChrisLively
– ChrisLively, Commented Sep 14, 2011 at 15:12
Another sidenote is that the tostring() of datetime creates a string with a space. The space makes the file lose it's type (also loses the hours and minutes of the datetime. — Peter Rasmussen
– Peter Rasmussen, Commented Sep 17, 2011 at 8:44

joshb · Accepted Answer · 2011-09-14 14:43:06Z

7

The following code worked for me. You may just be missing a file extension.

Response.Clear();
Response.ContentType = "text/csv";
Response.AppendHeader("Content-Disposition",
                string.Format("attachment; filename={0}.csv", DateTime.Now));
Response.Write(TextBox_Data.Text);
Context.Response.End();

answered Sep 14, 2011 at 14:43

joshb

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2 Comments

joshb Over a year ago

Keep in mind this code will not take care of things like escape characters but I assume that's what you're expecting.

Peter Rasmussen Over a year ago

ahh... I wrote the extension like this ("attachment; filename={0}", DateTime.Now+".csv")); This works perfectly from my home pc, Thanks a lot!

Community · Accepted Answer · 2017-05-23 12:17:02Z

Just a complement on joshb's answer regarding the use of Response.End():

MSDN does not recommend the use of Response.End() for non-error cases, and in some cases it can actually cause the client to lose some data .

In my case sometimes the downloaded csv would loose the last bytes of the last line, so I removed the Response.End() and used

    HttpContext.Current.ApplicationInstance.CompleteRequest()

instead, and I had to override the page's Render(HtmlTextWriter writer) method to not write anything on the request, since the csv was already writen.

public class PageBase : Page
{
    private bool performRegularPageRender = true;

    protected override void Render(HtmlTextWriter writer)
    {
        if (performRegularPageRender)
            base.Render(writer);
    }

    public void SkipRegularPageRendering()
    {
        performRegularPageRender = false;
    }
}

More info / credits: msdn blog; Is Response.End() considered harmful?; PostBack and Render Solutions? Overrides

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