Ask for location for saving downloaded file

Question

I am writting a code for downloading an excel file in the local system.

Microsoft.Office.Interop.Excel.Application excelApp = new Microsoft.Office.Interop.Excel.Application();
Microsoft.Office.Interop.Excel.Workbooks workBooks = excelApp.Workbooks;
Microsoft.Office.Interop.Excel.Workbook workBook = workBooks.Open(@"D:\Myfile.xlsx");
// Microsoft.Office.Interop.Excel.Worksheet workSheet = workBook.Worksheets.get_Item(1);

workBook.SaveCopyAs(@"D:\Copy_Myfile.xlsx");
workBook.Close();

Now the requirement is instead of saving the file to D drive, it should ask for the user to save the file to desied location.

Any idea?

Answer 1

public static void TransmitFile(Page CurrentPage, string FilePath)
// CurrentPage = this when called from CodeBehind
{
    if (File.Exists(FilePath))
    {
        string FileName = Path.GetFileName(FilePath);
        string Extension = Path.GetExtension(FilePath).ToLowerInvariant();
        string ContentType;

        switch (Extension)
        {
            case "xlsx":
                ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                break;
            case "xls":
                ContentType = "application/vnd.ms-excel";
                break;
            case "csv":
                ContentType = "text/csv";
                break;
            default:
                ContentType = "application/octet-stream";
                break;
        }

        if (CurrentPage != null)
        {
            CurrentPage.Response.ContentType = ContentType;
            CurrentPage.Response.AppendHeader("Content-Disposition", "attachment; filename=" + FileName);
            CurrentPage.Response.TransmitFile(FilePath);
            CurrentPage.Response.End();
        }
        else
            throw new Exception("File transmission failed: cannot access current page");
    }
    else
        throw new Exception("File transmission failed: file not found");
}