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Query Extender in ASP.NET

Introduction

This article demonstrates an interesting and very useful concept in ASP.NET.

Question: What is query extender?

In simple terms "It filters the data from a selected data source".

Step 1: Create a new web application

Output1.jpg

Step 2: Adding a new LINQ-to-SQL

Output2.jpg

Step 3: Add new data source to GridView

Output3.png

Output5.jpg

Output6.png

Output7.png

Output8.png

Step 4: The complete code of WebForm1.aspx is as in the following:

  1. <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="QueryExtenderApp.WebForm1" %>  
  2. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  
  3. <html xmlns="http://www.w3.org/1999/xhtml">  
  4. <head id="Head1" runat="server">  
  5.     <title></title>  
  6. </head>  
  7. <body>  
  8.     <form id="form1" runat="server">  
  9.     <center>  
  10.         <div>  
  11.             <table>  
  12.                 <tr>  
  13.                     <td colspan="3" align="center">  
  14.                         <asp:Label ID="Label2" runat="server" Text="Query Extender" Font-Bold="true" Font-Names="Verdana"  
  15.                             Font-Size="Large"></asp:Label>  
  16.                     </td>  
  17.                 </tr>  
  18.                 <tr>  
  19.                     <td>  
  20.                         <asp:Label ID="Label1" runat="server" Font-Names="Verdana" Font-Bold="true" Text="Please Filter By FirstName"></asp:Label>  
  21.                     </td>  
  22.                     <td>  
  23.                         <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>  
  24.                     </td>  
  25.                 </tr>  
  26.             </table>  
  27.         </div>  
  28.         <div>  
  29.             <asp:GridView ID="GridView1" runat="server" BackColor="LightGoldenrodYellow" BorderColor="Tan"  
  30.                 BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" AutoGenerateColumns="False"  
  31.                 DataKeyNames="EmpId" DataSourceID="LinqDataSource1">  
  32.                 <AlternatingRowStyle BackColor="PaleGoldenrod" />  
  33.                 <Columns>  
  34.                     <asp:BoundField DataField="EmpId" HeaderText="EmpId" InsertVisible="False" ReadOnly="True"  
  35.                         SortExpression="EmpId" />  
  36.                     <asp:BoundField DataField="FirstName" HeaderText="FirstName" SortExpression="FirstName" />  
  37.                     <asp:BoundField DataField="LastName" HeaderText="LastName" SortExpression="LastName" />  
  38.                     <asp:BoundField DataField="Age" HeaderText="Age" SortExpression="Age" />  
  39.                 </Columns>  
  40.                 <FooterStyle BackColor="Tan" />  
  41.                 <HeaderStyle BackColor="Tan" Font-Bold="True" />  
  42.                 <PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />  
  43.                 <SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />  
  44.                 <SortedAscendingCellStyle BackColor="#FAFAE7" />  
  45.                 <SortedAscendingHeaderStyle BackColor="#DAC09E" />  
  46.                 <SortedDescendingCellStyle BackColor="#E1DB9C" />  
  47.                 <SortedDescendingHeaderStyle BackColor="#C2A47B" />  
  48.             </asp:GridView>  
  49.             <asp:LinqDataSource ID="LinqDataSource1" runat="server" ContextTypeName="QueryExtenderApp.DataClasses1DataContext"  
  50.                 EntityTypeName="" TableName="Employees">  
  51.             </asp:LinqDataSource>  
  52.             <br />  
  53.             <asp:QueryExtender ID="QueryExtender1" runat="server" TargetControlID="LinqDataSource1">  
  54.                 <asp:SearchExpression DataFields="FirstName" SearchType="StartsWith">  
  55.                     <asp:ControlParameter ControlID="TextBox1" />  
  56.                 </asp:SearchExpression>  
  57.             </asp:QueryExtender>  
  58.         </div>  
  59.     </center>  
  60.     </form>  
  61. </body>  
  62. </html> 

Step 5: The complete code of WebForm1.aspx.cs is as in the following:

  1. using System;  
  2. using System.Collections.Generic;  
  3. using System.Linq;  
  4. using System.Web;  
  5. using System.Web.UI;  
  6. using System.Web.UI.WebControls;  
  7. namespace QueryExtenderApp  
  8. {  
  9.     public partial class WebForm1 : System.Web.UI.Page  
  10.     {  
  11.         protected void Page_Load(object sender, EventArgs e)  
  12.         {  
  13.         }  
  14.     }  
  15. } 

Step 6: The output of the application is as in the following:


Output9.png
Step 7: The selected output of the application is as in the following:

Output10.png


I hope this article was useful for you. 


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