Read an Excel file uploaded using FileUpload Control without saving it on the server

Question

Need to be able to read an Excel file uploaded using FileUploadControl in ASP.NET. The solution will be hosted on a server. I do not want to store the Excel file on the serv

Answer 1

You can use the InputStream property of the HttpPostedFile to read the file into memory.

Here's an example which shows how to create a DataTable from the IO.Stream of a HttpPostedFile using EPPlus:

protected void UploadButton_Click(Object sender, EventArgs e)
{
    if (FileUpload1.HasFile && Path.GetExtension(FileUpload1.FileName) == ".xlsx")
    {
        using (var excel = new ExcelPackage(FileUpload1.PostedFile.InputStream))
        {
            var tbl = new DataTable();
            var ws = excel.Workbook.Worksheets.First();
            var hasHeader = true;  // adjust accordingly
            // add DataColumns to DataTable
            foreach (var firstRowCell in ws.Cells[1, 1, 1, ws.Dimension.End.Column])
                tbl.Columns.Add(hasHeader ? firstRowCell.Text
                    : String.Format("Column {0}", firstRowCell.Start.Column));

            // add DataRows to DataTable
            int startRow = hasHeader ? 2 : 1;
            for (int rowNum = startRow; rowNum <= ws.Dimension.End.Row; rowNum++)
            {
                var wsRow = ws.Cells[rowNum, 1, rowNum, ws.Dimension.End.Column];
                DataRow row = tbl.NewRow();
                foreach (var cell in wsRow)
                    row[cell.Start.Column - 1] = cell.Text;
                tbl.Rows.Add(row);
            }
            var msg = String.Format("DataTable successfully created from excel-file. Colum-count:{0} Row-count:{1}",
                                    tbl.Columns.Count, tbl.Rows.Count);
            UploadStatusLabel.Text = msg;
        }
    }
    else 
    {
        UploadStatusLabel.Text = "You did not specify a file to upload.";
    }
}

Here's the VB.NET version:

Sub UploadButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    If (FileUpload1.HasFile AndAlso IO.Path.GetExtension(FileUpload1.FileName) = ".xlsx") Then
        Using excel = New ExcelPackage(FileUpload1.PostedFile.InputStream)
            Dim tbl = New DataTable()
            Dim ws = excel.Workbook.Worksheets.First()
            Dim hasHeader = True ' change it if required '
            ' create DataColumns '
            For Each firstRowCell In ws.Cells(1, 1, 1, ws.Dimension.End.Column)
                tbl.Columns.Add(If(hasHeader,
                                   firstRowCell.Text,
                                   String.Format("Column {0}", firstRowCell.Start.Column)))
            Next
            ' add rows to DataTable '
            Dim startRow = If(hasHeader, 2, 1)
            For rowNum = startRow To ws.Dimension.End.Row
                Dim wsRow = ws.Cells(rowNum, 1, rowNum, ws.Dimension.End.Column)
                Dim row = tbl.NewRow()
                For Each cell In wsRow
                    row(cell.Start.Column - 1) = cell.Text
                Next
                tbl.Rows.Add(row)
            Next
            Dim msg = String.Format("DataTable successfully created from excel-file Colum-count:{0} Row-count:{1}",
                                    tbl.Columns.Count, tbl.Rows.Count)
            UploadStatusLabel.Text = msg
        End Using
    Else
        UploadStatusLabel.Text = "You did not specify an excel-file to upload."
    End If
End Sub

For the sake of completeness, here's the aspx:

   
Select a file to upload: