how to apply pagging to data list control - asp.net

Question

i just want to make data list with pagging. here is my code :
public partial class Template_Management : System.Web.UI.Page
{
PagedDataSource adsource = null;
int pos;
protected void Page_Init(object sender, EventArgs e)
{
if (!IsPostBack)
{
adsource = new PagedDataSource();
}
}
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
.....
Session["StartAlpha"] = "All";
Session["GroupByCategory"] = -1;
Session["ColumnName"] = null;
Session["SearchText"] = null;
this.FillGrid((String)Session["StartAlpha"] ?? null, (int)Session["GroupByCategory"], (String)Session["ColumnName"] ?? null, (String)Session["SearchText"] ?? null);
this.ViewState["vs"] = 0;
}
pos = (int)this.ViewState["vs"];
}
}
public void FillGrid(string StartAlpha, int GroupByCategory, string ColumnName, string SearchText)
{
if (myDataSet.Tables[0].Rows.Count > 0)
{
adsource.DataSource = myDataSet.Tables[0].DefaultView;
adsource.AllowPaging = true;
adsource.PageSize = 20;
DL_ViewTemplate.DataSource = adsource;
}
if (DL_ViewTemplate.Items.Count != 0)
{
SetPageNumbers();
}
UpdatePanel8.Update();
DL_ViewTemplate.DataBind();
}
private void SetPageNumbers()
{
foreach (DataListItem item in DL_ViewTemplate.Items)
{
if (item.ItemType == ListItemType.Footer)
{
if (pos == 0)
{
ImageButton img = (ImageButton)item.FindControl("ImageButton1");
img.Enabled = false;
}
if (pos == adsource.PageCount - 1)
{
ImageButton img = (ImageButton)item.FindControl("ImageButton4");
img.Enabled = false;
}
}
}
}
protected void DL_ViewTemplate_ItemCommand(object source, DataListCommandEventArgs e)
{
int intCurIndex = adsource.CurrentPageIndex;
switch (e.CommandArgument.ToString())
{
case "first":
adsource.CurrentPageIndex = 0;
break;
case "prev":
CurrentPage -= 1;
break;
case "next":
CurrentPage += 1;
break;
case "last":
adsource.CurrentPageIndex = adsource.PageCount;
break;
}
this.FillGrid((String)Session["StartAlpha"] ?? null, (int)Session["GroupByCategory"], (String)Session["ColumnName"] ?? null, (String)Session["SearchText"] ?? null);
}
protected void DL_ViewTemplate_ItemDataBound(object sender, DataListItemEventArgs e)
{
foreach (DataListItem item in DL_ViewTemplate.Items)
{
if (item.ItemType == ListItemType.Footer && item.ItemType == ListItemType.Item)
{
// get your controls from the gridview
DropDownList ddlPages = (DropDownList)item.FindControl("ddlPages");
Label lblPageCount = (Label)item.FindControl("lblPageCount");
if (ddlPages != null)
{
// populate pager
for (int i = 0; i < adsource.PageCount; i++)
{
int intPageNumber = i + 1;
ListItem lstItem = new ListItem(intPageNumber.ToString());
if (i == adsource.CurrentPageIndex)
lstItem.Selected = true;
ddlPages.Items.Add(lstItem);
}
}
// populate page count
if (lblPageCount != null)
lblPageCount.Text = adsource.PageCount.ToString();
}
}
}
protected void ddlPages_SelectedIndexChanged(object sender, EventArgs e)
{
foreach (DataListItem item in DL_ViewTemplate.Items)
{
if (item.ItemType == ListItemType.Footer)
{
DropDownList ddlPages = (DropDownList)item.FindControl("ddlPages");
adsource.CurrentPageIndex = ddlPages.SelectedIndex;
//a method to populate your grid
this.FillGrid((String)Session["StartAlpha"] ?? null, (int)Session["GroupByCategory"], (String)Session["ColumnName"] ?? null, (String)Session["SearchText"] ?? null);
}
}
}
}
how ever footer control with ddl doesn't filled.
for more info i place html markup :
<asp:DataList ID="DL_ViewTemplate" runat="server" RepeatColumns="6"
ShowFooter="True" HorizontalAlign="Left" RepeatDirection="Horizontal"
DataKeyField="Id" onitemcommand="DL_ViewTemplate_ItemCommand"
ShowHeader="False" onitemcreated="DL_ViewTemplate_ItemCreated"
onitemdatabound="DL_ViewTemplate_ItemDataBound" CellPadding="1"
CellSpacing="3">
<ItemStyle HorizontalAlign="Left" Wrap="True" Width="40%" />
<ItemTemplate>
<div class="thumb" align="center" style="height:150px;width:130px">
<table width="40%" align="center">
<tr>
<td>
<asp:Literal ID="Literal4" runat="server"></asp:Literal><!-- Text=<'#Eval("TemplateBody")%>'-->
<ajaxToolkit:HoverMenuExtender ID="hme1" runat="Server"
TargetControlID="Literal4"
PopupControlID="Panel2"
DynamicContextKey='<%# Eval("Id") %>'
DynamicControlID="Panel2"
DynamicServiceMethod="GetDynamicContent"
PopupPosition="Right"
OffsetX="-25"
OffsetY="15"/>
</td>
</tr>
</table>
</div>
<table width="145px" align="left" style="border-color:Black;border-style:solid;border-width:1px;height:50px">
<tr>
<td align="center">
<table>
<tr>
<td><asp:CheckBox ID="ChkSelect" runat="server" onclick = "Check_Click(this)"/></td>
<td> </td>
<td><asp:LinkButton ID="LinkButton2" runat="server" CssClass="quicklink"
Text='<%# Eval("TemplateName").ToString().Length > 12 ? Eval("TemplateName").ToString().Substring(0,12)+"..." :Eval("TemplateName") %>' CommandName="ViewTemplate"
ToolTip ='<%# Eval("TemplateName")%>' CommandArgument='<%# Eval("Id") %>'></asp:LinkButton>
<br/>
<asp:Label ID="Label2" runat="server" CssClass="normaltext"
Text='<%# DataBinder.Eval(Container.DataItem, "CreatedDate", "{0:dd/MM/yyyy}") %>'
ToolTip='<%# Bind("CreatedDate","{0:F}") %>'></asp:Label></td>
</tr>
</table>
</td>
</tr>
</table>
</ItemTemplate>
<SeparatorTemplate> </SeparatorTemplate>
<FooterTemplate>
<table>
<tr>
<td>
<asp:ImageButton ID="ImageButton1" runat="server"
AlternateText="Go to First Page" CommandArgument="First" CommandName="Page"
ImageUrl="images/1330128819_resultset_first.png" />
</td>
<td>
<asp:ImageButton ID="ImageButton2" runat="server" AlternateText="Previous Page"
CommandArgument="Prev" CommandName="Page"
ImageUrl="images/1330128981_resultset_previous.png" />
</td>
<td>
Page <asp:DropDownList ID="ddlPages" runat="server" AutoPostBack="True"
onselectedindexchanged="ddlPages_SelectedIndexChanged" Width="50px">
</asp:DropDownList>
of
<asp:Label ID="lblPageCount" runat="server"></asp:Label>
</td>
<td>
<asp:ImageButton ID="ImageButton3" runat="server" AlternateText="Next Page"
CommandArgument="Next" CommandName="Page"
ImageUrl="images/Farm-Fresh_resultset_next.png" />
</td>
<td>
<asp:ImageButton ID="ImageButton4" runat="server"
AlternateText="Go to Last Page" CommandArgument="Last" CommandName="Page"
ImageUrl="images/1330128876_resultset_last.png" />
</td>
</tr>
</table>
</FooterTemplate>
<FooterStyle CssClass="pager" VerticalAlign="Bottom"
HorizontalAlign="Center" />
</asp:DataList>
here i set adsource which was paged data source declared first and assigned in Page_Init() is it valid ?? because when ever other event want to access adsource then Object reference not found error thrown.
what am i going wrong please help me....

Answer 1

you can refer these links for more information on paging on datalist control in ASP.net
http://www.c-sharpcorner.com/UploadFile/718fc8/paging-in-datalist-control/
http://www.codeproject.com/Articles/14080/Implementing-Efficient-Data-Paging-with-the-Datali