如何使用C＃将gridview导出到ASP.net中的Excel？

Question

Does someone know how I can export a gridview in ASP.net to Excel??

I use this code but I can't access my gridview because it's null

protected void BtnExport_Click(object sender, EventArgs e)
{
    DataTable dtOriginal = new DataTable();
    dtOriginal = (DataTable)gvRapporten.DataSource; //Return Table consisting data

    //Create Tempory Table
    DataTable dtTemp = new DataTable();

    //Creating Header Row
    dtTemp.Columns.Add("<b>Melder</b>");
    dtTemp.Columns.Add("<b>Onderwerp</b>");
    dtTemp.Columns.Add("<b>Oplosser</b>");
    dtTemp.Columns.Add("<b>Niveau 2</b>");
    DataRow drAddItem;
    for (int i = 0; i < dtOriginal.Rows.Count; i++)
    {
        drAddItem = dtTemp.NewRow();
        drAddItem[0] = dtOriginal.Rows[i][0].ToString();//Melder
        drAddItem[1] = dtOriginal.Rows[i][1].ToString();//Onderwerp
        drAddItem[2] = dtOriginal.Rows[i][2].ToString();//Oplosser
        drAddItem[3] = dtOriginal.Rows[i][3].ToString();//Niveau 2

        dtTemp.Rows.Add(drAddItem);
    }

    //Temp Grid
    DataGrid dg = new DataGrid();
    dg.DataSource = dtTemp;
    dg.DataBind();
    ExportToExcel("Report.xls", dg);
    dg = null;
    dg.Dispose();
}

private void ExportToExcel(string strFileName, DataGrid dg)
{
    Response.ClearContent();
    Response.AddHeader("content-disposition", "attachment; filename=" + strFileName);
    Response.ContentType = "application/excel";
    System.IO.StringWriter sw = new System.IO.StringWriter();
    HtmlTextWriter htw = new HtmlTextWriter(sw);
    dg.RenderControl(htw);
    Response.Write(sw.ToString());
    Response.End();
}

Answer 1

can you try this ?

System.IO.StringWriter sw = new System.IO.StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
Response.AddHeader("content-disposition", "attachment; filename=" + strFileName);
Response.ClearContent();

Response.AddHeader("content-disposition", attachment);

dg.RenderControl(htw);
Response.Write(sw.ToString());
Response.Flush();
Response.End();

Answer 2

You code simply generates a Html-Table(that is what ASP.Net renders a GridView/DataGrid to) and nothing else. Excel can handle this and display it like a Table but it is not really a xls - or csv -file.

The DataSource-property of a GridView is always null/nothing after postback. You should generate the DataSource again before you export it to excel.

This code converts any datatable to a csv-String:

C#

public static string tableToCsv(DataTable DT)
{
    System.Text.StringBuilder csv = new System.Text.StringBuilder();
    System.Text.StringBuilder rowData = new System.Text.StringBuilder();
    DataRow DR = null;
    DataColumn DC = null;

    foreach (DataColumn DC_loopVariable in DT.Columns) {
        DC = DC_loopVariable;
        rowData.Length = 0;
        rowData.Append((rowData.Length > 0 ? ";" : "").ToString());
        rowData.Append(DC.ColumnName);
    }
    csv.Append(rowData.ToString()).Append(Strings.Chr(13));

    foreach (DataRow DR_loopVariable in DT.Rows) {
        DR = DR_loopVariable;
        rowData.Length = 0;

        foreach (DataColumn DC_loopVariable in DT.Columns) {
            DC = DC_loopVariable;
            rowData.Append((rowData.Length > 0 ? ";" : "").ToString());
            rowData.Append(DR[DC.ColumnName].ToString());
        }
        csv.Append(rowData.ToString()).Append(Strings.Chr(13));
    }
    return csv.ToString();
}

VB

Public Shared Function tableToCsv(ByVal DT As DataTable) As String
    Dim csv As New System.Text.StringBuilder
    Dim rowData As New System.Text.StringBuilder
    Dim DR As DataRow
    Dim DC As DataColumn

    For Each DC In DT.Columns
        rowData.Length = 0
        rowData.Append(IIf(rowData.Length > 0, ";", "").ToString)
        rowData.Append(DC.ColumnName)
    Next
    csv.Append(rowData.ToString).Append(Chr(13))

    For Each DR In DT.Rows
        rowData.Length = 0

        For Each DC In DT.Columns
            rowData.Append(IIf(rowData.Length > 0, ";", "").ToString)
            rowData.Append(DR.Item(DC.ColumnName).ToString)
        Next
        csv.Append(rowData.ToString).Append(Chr(13))
    Next
    Return csv.ToString
End Function

Answer 3

Dim dt As DataTable = ViewState("FinalState")
Dim GV As New GridView
GV.DataSource = dt ' UpdateDataTable(ViewState("FinalTable"))
GV.DataBind()
Response.Clear()
Response.Buffer = True
Response.AddHeader("content-disposition", "attachment;filename=ProspectsBank.xls")
Response.Charset = ""
Response.ContentType = "application/vnd.ms-excel"
Dim sw As New StringWriter()
Dim hw As New HtmlTextWriter(sw)
For i As Integer = 0 To GV.Rows.Count - 1
    'Apply text style to each Row 
    GV.Rows(i).Attributes.Add("class", "textmode")
Next
GV.RenderControl(hw)
Dim style As String = "<style> .textmode { mso-number-format:\@; } </style>"
Response.Write(style)
Response.Output.Write(sw.ToString())
clsLog.SaveLogValue(Request.ServerVariables("REMOTE_ADDR"), "SearchAudienceForMagazine.aspx", "User Export Data From Our Databank in EXCEL format. Current they Exported " & dt.Rows.Count & " Data.", Session("User_TypeId"), Session("User_Name"))
Response.Flush()
Response.End()