Generating an excel file with EPPlus is failing

15
votes

When I try to generate an Excel file using EPPlus, Excel give me the following error message:

Excel cannot open the file 'myfilename.xlsx' because the file format or file extension is not valid. Verify the the file has not been corrupted and that the file extension matches the format of the file.

Here's my code:

public ActionResult Index()
{
    using (ExcelPackage package = new ExcelPackage())
    {
        // I populate the worksheet here.  I'm 90% sure this is fine
        // because the stream file size changes based on what I pass to it.

        var stream = new MemoryStream();
        package.SaveAs(stream);

        string fileName = "myfilename.xlsx";
        string contentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

        var cd = new System.Net.Mime.ContentDisposition
        {
            Inline = false,
            FileName = fileName
        };
        Response.AppendHeader("Content-Disposition", cd.ToString());
        return File(stream, contentType, fileName);
    }
}

Any idea what I'm doing wrong?

3
c#asp.net-mvcexcelepplus
The error says myfilename.xslx while your code shows myfilename.xlsx. Which one are you really using? – M.Babcock
Answered yesterday. I assume that this is the same issue. – Tim Schmelter
@M.Babcock - xlsx, it was a typo. I'll edit the question. – Matt Grande
I found this code worked when I set the stream position to 0 and I found it cleaner than the accepted solution. – stimms

3 Answers

30
votes

All you need to do is reset the stream position. stream.Position = 0;

You shouldn't write directly to the Response, it's not the MVC way. It doesn't follow the correct MVC pipeline and it tightly couples your controller action code to the Response object.

When you add a file name as the 3rd parameter in File(), MVC automatically adds the correct Content-Disposition header... so you shouldn't need to add it manually.

The short of it is, this is what you want:

public ActionResult Index()
{
    using (ExcelPackage package = new ExcelPackage())
    {
        // I populate the worksheet here.  I'm 90% sure this is fine
        // because the stream file size changes based on what I pass to it.

        var stream = new MemoryStream();
        package.SaveAs(stream);

        string fileName = "myfilename.xlsx";
        string contentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

        stream.Position = 0;
        return File(stream, contentType, fileName);
    }
}
10
votes

Your code doesn't show stream being written to the HttpResponse - presumably being done in the File method which you haven't posted.

One way that does work is the following:

Response.Clear();
Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
Response.AddHeader(
            "content-disposition", String.Format(CultureInfo.InvariantCulture, "attachment; filename={0}", fileName));
Response.BinaryWrite(package.GetAsByteArray());
Response.End();
2
votes

Similar to Joe's answer, I still had to call Response.ClearHeaders():

   protected void btnDownload_Click(object sender, EventArgs e)
   {

       ExcelPackage pck = new ExcelPackage();
       var ws = pck.Workbook.Worksheets.Add("Sample2");

       ws.Cells["A1"].Value = "Sample 2";
       ws.Cells["A1"].Style.Font.Bold = true;
       var shape = ws.Drawings.AddShape("Shape1", eShapeStyle.Rect);
       shape.SetPosition(50, 200);
       shape.SetSize(200, 100);
       shape.Text = "Sample 2 outputs the sheet using the Response.BinaryWrite method";
       Response.Clear();    
       Response.ClearHeaders();
       Response.BinaryWrite(pck.GetAsByteArray());
       Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
       Response.AddHeader("content-disposition", "attachment;  filename=Sample2.xlsx");
       Response.End();
  }