Generating an Excel file in ASP.NET [closed]

Question

I am about to add a section to an ASP.NET app (VB.NET codebehind) that will allow a user to get data returned to them as an Excel file, which I will generate based on database data. While there are several ways of doing this, each has its own drawbacks. How would you return the data? I'm looking for something that's as clean and straightforward as possible.

Answer 1

I either go the CSV route (as described above), or more often these days, I use Infragistics NetAdvantage to generate the file. (The very vast majority of the time where Infragistics is in play, we're just exporting an existing UltraWebGrid, which is essentially a one-LOC solution unless extra formatting tweaks are needed. We could manually generate an Excel/BIFF file as well, but there's rarely a need to.)

Answer 2

If coming from a DataTable:

public static void DataTabletoXLS(DataTable DT, string fileName)
{
    HttpContext.Current.Response.Clear();
    HttpContext.Current.Response.Charset = "utf-16";
    HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("windows-1250");
    HttpContext.Current.Response.AddHeader("content-disposition", string.Format("attachment; filename={0}.xls", fileName));
    HttpContext.Current.Response.ContentType = "application/ms-excel";

    string tab = "";
    foreach (DataColumn dc in DT.Columns)
    {
        HttpContext.Current.Response.Write(tab + dc.ColumnName.Replace("\n", "").Replace("\t", ""));
        tab = "\t";
    }
    HttpContext.Current.Response.Write("\n");

    int i;
    foreach (DataRow dr in DT.Rows)
    {
        tab = "";
        for (i = 0; i < DT.Columns.Count; i++)
        {
            HttpContext.Current.Response.Write(tab + dr[i].ToString().Replace("\n", "").Replace("\t", ""));
            tab = "\t";
        }
        HttpContext.Current.Response.Write("\n");
    }
    HttpContext.Current.Response.End();
}

From a Gridview:

public static void GridviewtoXLS(GridView gv, string fileName)
{
    int DirtyBit = 0;
    int PageSize = 0;
    if (gv.AllowPaging == true)
    {
        DirtyBit = 1;
        PageSize = gv.PageSize;
        gv.AllowPaging = false;
        gv.DataBind();
    }

    HttpContext.Current.Response.Clear();
    HttpContext.Current.Response.Charset = "utf-8";
    HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("windows-1250");
    HttpContext.Current.Response.AddHeader(
        "content-disposition", string.Format("attachment; filename={0}.xls", fileName));
    HttpContext.Current.Response.ContentType = "application/ms-excel";

    using (StringWriter sw = new StringWriter())
    using (HtmlTextWriter htw = new HtmlTextWriter(sw))
    {
        //  Create a table to contain the grid
        Table table = new Table();

        //  include the gridline settings
        table.GridLines = gv.GridLines;

        //  add the header row to the table
        if (gv.HeaderRow != null)
        {
            Utilities.Export.PrepareControlForExport(gv.HeaderRow);
            table.Rows.Add(gv.HeaderRow);
        }

        //  add each of the data rows to the table
        foreach (GridViewRow row in gv.Rows)
        {
            Utilities.Export.PrepareControlForExport(row);
            table.Rows.Add(row);
        }

        //  add the footer row to the table
        if (gv.FooterRow != null)
        {
            Utilities.Export.PrepareControlForExport(gv.FooterRow);
            table.Rows.Add(gv.FooterRow);
        }

        //  render the table into the htmlwriter
        table.RenderControl(htw);

        //  render the htmlwriter into the response
        HttpContext.Current.Response.Write(sw.ToString().Replace("£", ""));
        HttpContext.Current.Response.End();
    }

    if (DirtyBit == 1)
    {
        gv.PageSize = PageSize;
        gv.AllowPaging = true;
        gv.DataBind();
    }
}

private static void PrepareControlForExport(Control control)
{
    for (int i = 0; i < control.Controls.Count; i++)
    {
        Control current = control.Controls[i];
        if (current is LinkButton)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as LinkButton).Text));
        }
        else if (current is ImageButton)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as ImageButton).AlternateText));
        }
        else if (current is HyperLink)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as HyperLink).Text));
        }
        else if (current is DropDownList)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as DropDownList).SelectedItem.Text));
        }
        else if (current is CheckBox)
        {
            control.Controls.Remove(current);
            control.Controls.AddAt(i, new LiteralControl((current as CheckBox).Checked ? "True" : "False"));
        }

        if (current.HasControls())
        {
            Utilities.Export.PrepareControlForExport(current);
        }
    }
}

Answer 3

just created a function to export from a web form C# to excel hope it helps others

    public void ExportFileFromSPData(string filename, DataTable dt)
    {
        HttpResponse response = HttpContext.Current.Response;

        //clean up the response.object
        response.Clear();
        response.Buffer = true;
        response.Charset = "";

        // set the response mime type for html so you can see what are you printing 
        //response.ContentType = "text/html";
        //response.AddHeader("Content-Disposition", "attachment;filename=test.html");

        // set the response mime type for excel
        response.ContentType = "application/vnd.ms-excel";
        response.AddHeader("Content-Disposition", "attachment;filename=\"" + filename + "\"");
        response.ContentEncoding = System.Text.Encoding.UTF8;
        response.BinaryWrite(System.Text.Encoding.UTF8.GetPreamble());

        //style to format numbers to string
        string style = @"<style> .text { mso-number-format:\@; } </style>";
        response.Write(style);

        // create a string writer
        using (StringWriter sw = new StringWriter())
        {
            using (HtmlTextWriter htw = new HtmlTextWriter(sw))
            {
                // instantiate a datagrid
                GridView dg = new GridView();
                dg.DataSource = dt;
                dg.DataBind();

                foreach (GridViewRow datarow in dg.Rows)
                {
                    //format specific cell to be text 
                    //to avoid 1.232323+E29 to get 1232312312312312124124
                    datarow.Cells[0].Attributes.Add("class", "text");
                }

                dg.RenderControl(htw);
                response.Write(sw.ToString());
                response.End();
            }
        }
     }

Answer 4

Here's a report that pulls from a stored procedure. The results are exported to Excel. It uses ADO instead of ADO.NET and the reason why is this line

oSheet.Cells(2, 1).copyfromrecordset(rst1)

It does most of the work and isn't available in ado.net.

‘Calls stored proc in SQL Server 2000 and puts data in Excel and ‘formats it

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim cnn As ADODB.Connection
        cnn = New ADODB.Connection
        cnn.Open("Provider=SQLOLEDB;data source=xxxxxxx;" & _
          "database=xxxxxxxx;Trusted_Connection=yes;")

        Dim cmd As New ADODB.Command


        cmd.ActiveConnection = cnn


        cmd.CommandText = "[sp_TomTepley]"
        cmd.CommandType = ADODB.CommandTypeEnum.adCmdStoredProc
        cmd.CommandTimeout = 0
        cmd.Parameters.Refresh()


        Dim rst1 As ADODB.Recordset
        rst1 = New ADODB.Recordset
        rst1.Open(cmd)

        Dim oXL As New Excel.Application
        Dim oWB As Excel.Workbook
        Dim oSheet As Excel.Worksheet

        'oXL = CreateObject("excel.application")
        oXL.Visible = True
        oWB = oXL.Workbooks.Add
        oSheet = oWB.ActiveSheet

        Dim Column As Integer
        Column = 1

        Dim fld As ADODB.Field
        For Each fld In rst1.Fields

            oXL.Workbooks(1).Worksheets(1).Cells(1, Column).Value = fld.Name
            oXL.Workbooks(1).Worksheets(1).cells(1, Column).Interior.ColorIndex = 15
            Column = Column + 1

        Next fld

        oXL.Workbooks(1).Worksheets(1).name = "Tom Tepley Report"
        oSheet.Cells(2, 1).copyfromrecordset(rst1)
        oXL.Workbooks(1).Worksheets(1).Cells.EntireColumn.AutoFit()


        oXL.Visible = True
        oXL.UserControl = True

        rst1 = Nothing

        cnn.Close()
        Beep()

    End Sub

Answer 5

You can create nicely formatted Excel files using this library, quite easily: http://officehelper.codeplex.com/documentation.

Microsoft Office does not need to be installed on the webserver!

Answer 6

This is a free wrapper around SpreadML--it works great.

http://www.carlosag.net/Tools/ExcelXmlWriter/