在RowCommand

Question

我的网格视图包含rowcommand和linkbutton。当我按下链接按钮时，行被编辑但是DDL应该使用我的数据库表中的值绑定数据但是这不起作用

我不知道这是否是正确的方法，但是按下linkbutton时出现错误 “对象引用未设置为对象的实例。”但我认为这不是主要问题。

我应该在从Rowcommand编辑时绑定我的DDL行，还是任何人都可以看到我做错了什么？

DDL列的ASPX标记：

<asp:TemplateField HeaderText="Status">
                 <EditItemTemplate>
                     <asp:DropDownList ID="ddlStatusRow" AppendDataBoundItems="True" runat="server" > 
                       <asp:ListItem>Status</asp:ListItem>  

                     </asp:DropDownList>
                     <asp:RequiredFieldValidator ID="rfEditStatus" runat="server" ErrorMessage ="Status is a required field"
                         ControlToValidate="ddlStatusRow" Text="*" ForColor="Red" InitialValue="Status">
                     </asp:RequiredFieldValidator>
                 </EditItemTemplate>
                 <ItemTemplate>
                     <asp:Label ID="Label1" runat="server" Text='<%# Bind("Status") %>'></asp:Label>
                 </ItemTemplate>
                 <HeaderStyle BackColor="#E6E6E6" Font-Bold="False" Font-Names="Arial" Font-Size="14px" ForeColor="Black" />
                 <ItemStyle Font-Size="12px" HorizontalAlign="Center" Width="4%" />
             </asp:TemplateField>

代码隐藏：

protected void gwUnplannedActivities_RowCommand(object sender, GridViewCommandEventArgs e)
{

    if (e.CommandName == "EditRow")
    {
        int rowIndex = ((GridViewRow)((LinkButton)e.CommandSource).NamingContainer).RowIndex;
        gwUnplannedActivities.EditIndex = rowIndex;
        BindGridViewUnplannedActivities();

        GridViewRow row = ((e.CommandSource as Control).NamingContainer as GridViewRow);
        DropDownList ddlStatusRow = (DropDownList)row.Cells[3].FindControl("ddlStatusRow");  


        string CS = ConfigurationManager.ConnectionStrings["DBCS"].ConnectionString;


        using (SqlConnection con = new SqlConnection(CS))
        {
            SqlCommand cmd = new SqlCommand("SELECT * FROM ....", con);
            con.Open();
            ddlStatusRow.DataSource = cmd.ExecuteReader();
            ddlStatusRow.DataTextField = "Status";
            ddlStatusRow.DataBind();
        }

    }
    else if (e.CommandName == "CancelUpdate")
    {
       //somecode....
    }
    else if (e.CommandName == "UpdateRow")
    {
        //somecode....
    }


}