在单击按钮时显示gridview

Question

First i try to displaly gridview on pageload so girdveiw succesffully displayed now i try to display when click on button i try below code but grid not visible

Code

   DataTable dt = new DataTable();
    public DataTable info(string id)
      try
        {
            Entities2 wr = new Entities2();
            List<spv_Result> sv = wr.spvec(id).ToList();
            dt.Columns.Add("RowNumber", typeof(int));
            foreach (var c in sv)
            {
                dt.Rows.Add(c.RowNumber);
            }     
            return dt;
        }
        catch (Exception ex)
        {
            throw new Exception();
        }

    }

protected void Button1_Click(object sender, EventArgs e)
    {
        info(id);
        GridView1.DataSource = dt;
        GridView1.DataBind();

    }

there is data in dt but gridview not display

<asp:GridView ID="GridView1" runat="server" class="display nowrap"
    Width="100%" CellPadding="0"
    Font-Names="Verdana" BackColor ="White" BorderColor="#CCCCCC" BorderStyle="None" 
    BorderWidth="1px" Font-Size="9pt">
<FooterStyle BackColor="White" ForeColor="#000066" />
<HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
<RowStyle ForeColor="#000066" />
<SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#F1F1F1" />
<SortedAscendingHeaderStyle BackColor="#007DBB" />
<SortedDescendingCellStyle BackColor="#CAC9C9" />
<SortedDescendingHeaderStyle BackColor="#00547E" />

any solution?

Answer 1

I think "dt" has no value in below line for button click event.

GridView1.DataSource = dt;

Try this:

protected void Button1_Click(object sender, EventArgs e)
{
    GridView1.DataSource = info(id);
    GridView1.DataBind();
}

or 

protected void Button1_Click(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    dt = info(id);
    GridView1.DataSource = dt;
    GridView1.DataBind();
}

Here, "info" method directly returns datatable, then values are assigned to Gridview.