Paging in child grid view not working - asp.net

Question

Hi all I am doing a program with a nested gridview my design is as follows
<asp:Panel CssClass="grid" ID="pnlCust" runat="server">
<asp:UpdatePanel ID="pnlUpdate" runat="server">
<ContentTemplate>
<asp:GridView AllowPaging="True" ID="gvCustomers" AutoGenerateColumns="False" DataKeyNames="EmpID"
runat="server" ShowHeader="true" BackColor="White" BorderColor="#DEDFDE" BorderStyle="None"
BorderWidth="1px" CellPadding="4" ForeColor="Black" GridLines="Vertical" >
<AlternatingRowStyle BackColor="White" />
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:Panel CssClass="group" ID="pnlCustomer" runat="server">
<%--<asp:Image ID="imgCollapsible" CssClass="first" ImageUrl="~/Assets/img/plus.png"
Style="margin-right: 5px;" runat="server" /><span class="header">
<%#Eval("EmpID")%>
:
<%#Eval("empname")%>--%>
<asp:RadioButton ID="rdbtn" runat="server" onclick="RadioCheck(this);" OnCheckedChanged="radio_changed" Text='<%# Bind("EmpID") %>'
AutoPostBack="true"></asp:RadioButton>
</asp:Panel>
<asp:Panel Style="margin-left: 20px; margin-right: 20px" ID="pnlOrders" runat="server">
<asp:GridView AutoGenerateColumns="false" CssClass="grid" ID="gvOrders" runat="server"
PageSize="1" ShowHeader="true" EnableViewState="false" DataKeyNames="EmpID" AllowPaging="true"
OnPageIndexChanging="gvOrders_PageIndexChanging">
<RowStyle CssClass="row" />
<AlternatingRowStyle CssClass="altrow" />
<Columns>
<asp:BoundField HeaderText="Employee Id" DataField="EmpID">
<ItemStyle HorizontalAlign="Center" Width="100px" />
</asp:BoundField>
<asp:TemplateField ItemStyle-CssClass="rownum">
<ItemTemplate>
<%# Container.DataItemIndex + 1 %>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderStyle-BackColor="#EFF1F1" ItemStyle-HorizontalAlign="Center"
ItemStyle-Height="25" HeaderStyle-Width="50" ItemStyle-Width="50">
<HeaderTemplate>
<input id="chkBoxAll" type="checkbox" onclick="checkAllBoxes()" />
</HeaderTemplate>
<ItemTemplate>
<asp:CheckBox ID="chkBoxChild" runat="server" />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="PayPeriodNumber" HeaderText="PayPeriod" HeaderStyle-BackColor="#EFF1F1"
ItemStyle-HorizontalAlign="Center" HeaderStyle-Width="80" ItemStyle-Width="80">
</asp:BoundField>
<asp:BoundField DataField="PayRollYear" HeaderText="Payroll Year" HeaderStyle-BackColor="#EFF1F1"
ItemStyle-HorizontalAlign="Center" HeaderStyle-Width="100" ItemStyle-Width="100">
</asp:BoundField>
<asp:BoundField DataField="PaymentDate" HeaderText="Payment Date" HeaderStyle-BackColor="#EFF1F1"
ItemStyle-HorizontalAlign="Center" HeaderStyle-Width="110" ItemStyle-Width="110">
</asp:BoundField>
</Columns>
</asp:GridView>
</asp:Panel>
</ItemTemplate>
</asp:TemplateField>
</Columns>
<FooterStyle BackColor="#CCCC99" />
<HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
<RowStyle BackColor="#F7F7DE" />
<SelectedRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
<SortedAscendingCellStyle BackColor="#FBFBF2" />
<SortedAscendingHeaderStyle BackColor="#848384" />
<SortedDescendingCellStyle BackColor="#EAEAD3" />
<SortedDescendingHeaderStyle BackColor="#575357" />
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>
</asp:Panel>
Image of that on Page load
On selecting one of the radio buttons I will show the corresponding Employee details which is as follows
I have written paging for gridview as follows
if (!Page.IsPostBack)
{
GridViewChildPageIndex();
}
private void GridViewChildPageIndex()
{
DataTable dtPageIndex = new DataTable();
dtPageIndex.Columns.Add("PageIndex", typeof(int));
for (int i = 0; i < gvCustomers.Rows.Count; i++)
{
dtPageIndex.Rows.Add("0");
}
Session["ChildPageIndex"] = dtPageIndex;
}
Paging code of child gridview is as follows
protected void gvOrders_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
GridView gvwChild = (GridView)sender;
//GridViewRow gvRowParent = ((System.Web.UI.WebControls.GridView)sender).Parent as GridViewRow;
GridViewRow gvRowParent = gvwChild.Parent as GridViewRow;
gvwChild.PageIndex = e.NewPageIndex;
if (Session["ChildPageIndex"] != null)
{
DataTable dtPageIndex = (DataTable)Session["ChildPageIndex"];
dtPageIndex.Rows[gvRowParent.RowIndex][1] = e.NewPageIndex; // *I am getting error here as Object reference not set to an Object can any one tell where I went wrong*
}
BindChildGrdView(gvCustomers.DataKeys[gvRowParent.RowIndex].Value.ToString(), gvwChild);
}
Stack Trace
at _Default.gvOrders_PageIndexChanging(Object sender, GridViewPageEventArgs e) in d:\Projects\GridView-Collapsible\GridView-Collapsible\Default.aspx.cs:line 54
at System.Web.UI.WebControls.GridView.OnPageIndexChanging(GridViewPageEventArgs e)
at System.Web.UI.WebControls.GridView.HandlePage(Int32 newPage)
at System.Web.UI.WebControls.GridView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup)
at System.Web.UI.WebControls.GridView.RaisePostBackEvent(String eventArgument)
at System.Web.UI.WebControls.GridView.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

Answer 1

This may help you out:
In the gvOrders_PageIndexChanging function, use
GridViewRow gvRowParent = gvwChild.Parent.Parent as GridViewRow;
And inside the if condition
if (Session["ChildPageIndex"] != null)
{
DataTable dtPageIndex = (DataTable)Session["ChildPageIndex"];
dtPageIndex.Rows[gvRowParent.RowIndex][0] = e.NewPageIndex; // *I am getting error here as Object reference not set to an Object can any one tell where I went wrong*
}
And also could you debug and check if gvRowParent is an instantiated object in the second line of this function.