Paging with a Data Source Control

PagerDataSource using a Data Source and custom paging

This sample shows how to use the PagerDataSource to obtain data from a custom data source in order to populate a DataList. In this sample we'll get the data directly from our data mapper, using a method that retrieves the data needed for the current page (the method is GetPagedData(int startIndex, int maxRows)). To see an example where we use a method that retrieves all the data from a data source choose the sample "Paging a Data Source (1)".

The PagerDataSource control acts as a data source and as a data consumer. The DataList will consume the data exposed by the PagerDataSource (the data of the current page), and the PagerDataSource will consume the data retrieved from the data mapper.

If the PagerDataSource is not bound to a DataSourceControl, it can not exploit the high degree of integration obtained by using the new ASP.NET 2.0 DataSourceControls, so we have to write some code in order to provide the data to the control.

When the PagerDataSource changes the page to show (and the first time it executes), it will raise the PageChanged event. If the PagerDataSource is bound to a DataSourceControl (using the DataSourceID property), it will fetch the data from the DataSourceControl automatically. However, if the control is not bound to a DataSourceControl, we have do some things in order to provide the data for the current page:

As we are going to bind only the current page, we have to set the property CustomPaging property to "true" in the PagerDataSource.

Set the DataSource property with the data for the current page. In order to know which items to retrieve we can use the properties StartIndex and MaxRows from the PageChangedEventArgs instance passed to the PageChanged event.

Call the DataBind method.

We have to set the total item count (using the TotalItemCount property present in the PageChangedEventArgs instance passed to the PageChanged event) so the PagerDataSource will find out the total number of pages to show.

The source code for this page is shown after the live sample.

Product List

Product 1

Full description for product number 1

2.00 $

Product 2

Full description for product number 2

4.00 $

Product 3

Full description for product number 3

6.00 $

Product 4

Full description for product number 4

8.00 $

Product 5

Full description for product number 5

10.00 $

Product 6

Full description for product number 6

12.00 $

Product 7

Full description for product number 7

14.00 $

Product 8

Full description for product number 8

16.00 $

Product 9

Full description for product number 9

18.00 $

Product 10

Full description for product number 10

20.00 $

Product 11

Full description for product number 11

22.00 $

Product 12

Full description for product number 12

24.00 $

Product 13

Full description for product number 13

26.00 $

Product 14

Full description for product number 14

28.00 $

Sample source code

The ASPX file for this sample is:.

                <%@
                Page Language="C#" MasterPageFile="~/DefaultMaster.master" AutoEventWireup="true" CodeFile="Paging_DataSource2.aspx.cs" Inherits="Paging_DataSourceId2" Title="Paging with a Data Source Control"
                %>

                <%@
                Register Assembly="PagerDataSource" Namespace="Manu.Web.UI.WebControls" TagPrefix="manu" %>

                <asp:Content 
                        ID="Content1" ContentPlaceHolderID="Content" Runat="Server">

                    <h2>Product
                List</h2>

                    <asp:DataList
                    ID="DataList1" runat="server" 
            
                        DataKeyField="id"
                DataSourceID="PagerDataSource1" 

                        RepeatColumns="7"
                RepeatDirection="Horizontal"
                Width="100%">

                        <ItemTemplate>

                            <table>

                                <tr>

                    <td align="center">

                <asp:Label 
                        ID="idLabel" runat="server"
            
                Text='<%# Eval("id") %>'></asp:Label>

                    </td>

                                </tr>

                                <tr>

                    <td align="center">

                <b><asp:Label
                ID="nameLabel"
                runat="server"
            
                Text='<%# Eval("name") %>'></asp:Label></b>

                    </td>

                                </tr>

                                <tr>

                    <td align="center">

                <asp:Label 
                        ID="descriptionLabel" 
                            runat="server"
            
                Text='<%# Eval("description") %>'></asp:Label>

                    </td>

                                </tr>

                                <tr>

                    <td align="center">

                <asp:Label 
                        ID="priceLabel" runat="server"
            
                Text='<%# Eval("price", "{0:#0.00}") %>'>

                </asp:Label>
                $

                    </td>

                                </tr>

                            </table>

                        </ItemTemplate>

                    </asp:DataList>

                    <manu:PagerDataSource
                ID="PagerDataSource1"
                runat="server"
            
                        PageSize="14"
                CustomPaging="true"
                OnPageChanged="PagerDataSource1_PageChanged">

                    </manu:PagerDataSource>

                </asp:Content>

The code-behind file (ASPX.CS) is:

            using System;

            using Manu.Web.UI.WebControls;

            public partial
            class Paging_DataSourceId2
            : System.Web.UI.Page

            {

                protected void
            Page_Load(object sender, 
                EventArgs e)

                {

                }

                protected void
            PagerDataSource1_PageChanged(object sender, PageChangedEventArgs e)

                {

                    ProductsDAL prodsDAL
            = new ProductsDAL();

                    PagerDataSource1.DataSource = prodsDAL.GetPagedData(e.StartIndex,
            e.MaxRows);

                    PagerDataSource1.DataBind();

                    e.TotalItemCount = prodsDAL.CountAll();

                }

            }