im refering http://www.aspsnippets.com/Articles/Nested-GridView-Example-in-ASPNet-using-C-and-VBNet.aspx and i have one dropdown list in child grid view
<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" CssClass="Grid"
onrowdatabound="gvCustomers_RowDataBound" Width="100%"
onrowcommand="gvCustomers_RowCommand" >
<RowStyle HorizontalAlign="Center" />
<AlternatingRowStyle HorizontalAlign="Center" />
<Columns>
<asp:TemplateField>
<ItemTemplate>
<img alt = "" style="cursor: pointer" src="images1/plus.png" />
<asp:Panel ID="pnlOrders" runat="server" Style="display: none">
<asp:GridView ID="gvOrders" runat="server" AutoGenerateColumns="false" CssClass = "ChildGrid" ShowHeaderWhenEmpty="true">
<RowStyle HorizontalAlign="Center" />
<AlternatingRowStyle HorizontalAlign="Center" />
<Columns>
<asp:BoundField DataField="OrderDate" HeaderText="Order Date" />
<asp:TemplateField>
<ItemTemplate>
<asp:DropDownList ID="drp1" runat="server" OnSelectedIndexChanged=" DropDownList1_SelectedIndexChanged" AutoPostBack="false" Width="100%" >
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</asp:Panel>
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="custname" HeaderText="Customer Name" />
<asp:BoundField DataField="id" HeaderText="Master OrderId" Visible="false" />
<asp:BoundField DataField="NoOfOrders" HeaderText="No. Of Orders" />
</Columns>
</asp:GridView>
protected void gvCustomers_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
DataSet ds=new Dataset();
Int64 id = Convert.ToInt64(DataBinder.Eval(e.Row.DataItem, "id"));
ds= service.Myservice(id);
DropDownList drplist = e.Row.FindControl("drp1") as DropDownList; // instead of this how can i access
drplist.DataSource=ds.Tables[0].Rows[0][1];
//Object reference not set to an instance of an object.
}
}
and also i tried GridView gvchild = e.Row.FindControl("gvOrders") as GridView; drplist = gvchild.FindControl("drp1") as DropDownList; // den also same error object reference not set to an instance of an obj