Gridview: Export to csv issue

Question

I have the following scenario. I have two methods of populating a GridView with data. These are as follows:

protected void btSearch_Click(object sender, EventArgs e)
{

    lqPackWeights.WhereParameters.Clear();
    ControlParameter cp = new ControlParameter();
    cp.Type = TypeCode.String;


    if (radBuyer.Checked)
    {
        cp.ControlID = "ddlProd";
        cp.PropertyName = "SelectedValue";
        lbRadMiss.Text = "";
    }

    else if (radProd.Checked)
    {
        cp.ControlID = "tbxProdAC";
        cp.PropertyName = "Text";
        lbRadMiss.Text = "";
    }

    else
    {
        cp.ControlID = "lbRadMiss";
        cp.PropertyName = "Text";
        lbRadMiss.Text = "Please check appropriate radio button before you attempt a search";
    }

    cp.Name = "IDDesc";
    lqPackWeights.WhereParameters.Add(cp);
    GridView1.DataSourceID = "lqPackWeights";
    GridView1.DataBind();

}

And

protected void btnShowPaper_Click(object sender, EventArgs e)
{
    ORWeightsDataClassesDataContext dbPa = new ORWeightsDataClassesDataContext();
    int max = 0;
    if (int.TryParse(txtbxHowMany.Text, out max))
    {
        var queryPa = dbPa.tblOnlineReportingCOMPLETEWeights
                    .Where(x => x.MaterialLevel == "Primary" && x.MaterialText == "Paper" && x.MemberId == "FM00012")
                    .OrderByDescending(x => x.ProductPercentage).Take(max);

        GridView1.DataSource = queryPa;
        GridView1.DataBind();

These both work fine in populating the gridview with their approrpiate data set.

I also have the following code that exports the gridview content to csv:

protected void btnExportCSV_Click(object sender, EventArgs e)
{
    Response.Clear();
    Response.Buffer = true;
    Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.csv");
    Response.Charset = "";
    Response.ContentType = "application/text";

    GridView1.AllowPaging = false;
    GridView1.DataBind();

    StringBuilder sb = new StringBuilder();
    for (int k = 0; k < GridView1.Columns.Count; k++)
    {
        sb.Append(GridView1.Columns[k].HeaderText + ',');
    }

    sb.Append("\r\n");
    for (int i = 0; i < GridView1.Rows.Count; i++)
    {
        for (int k = 0; k < GridView1.Columns.Count; k++)
        {
            sb.Append(GridView1.Rows[i].Cells[k].Text + ',');
        }
        sb.Append("\r\n");
    }
    Response.Output.Write(sb.ToString());
    Response.Flush();
    Response.End();

}

The export to csv works perfectly well in the first situation (i.e. the if/else if scenario) but when it comes to the second scenario, only the headings are extracted.

What's going on here then?! I have added in a few breaks and it looks like the export to csv code is being executed, however the actual GridView content is not placed onto the same csv file.

Any ideas?

Answer 1

Make sure you are rebinding your data BEFORE you do your export. I ran into this same issue a while back on a project, as we had VIEWSTATE turned off on the GridView, so on the postback we were trying to export the data, prior to the grid being populated with data.