Query Extender in ASP.NET

Vijay Prativadi
11y
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Article

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

Step 2: Adding a new LINQ-to-SQL

Step 3: Add new data source to GridView

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

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="QueryExtenderApp.WebForm1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

</head>

<body>

<div>

<table>

<tr>

<asp:Label ID="Label2" runat="server" Text="Query Extender" Font-Bold="true" Font-Names="Verdana"

Font-Size="Large"></asp:Label>

</td>

</tr>

<tr>

<td>

<asp:Label ID="Label1" runat="server" Font-Names="Verdana" Font-Bold="true" Text="Please Filter By FirstName"></asp:Label>

</td>

<td>

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

</td>

</tr>

</table>

</div>

<div>

<asp:GridView ID="GridView1" runat="server" BackColor="LightGoldenrodYellow" BorderColor="Tan"

BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" AutoGenerateColumns="False"

DataKeyNames="EmpId" DataSourceID="LinqDataSource1">

<asp:BoundField DataField="EmpId" HeaderText="EmpId" InsertVisible="False" ReadOnly="True"

SortExpression="EmpId" />

<asp:BoundField DataField="FirstName" HeaderText="FirstName" SortExpression="FirstName" />

<asp:BoundField DataField="LastName" HeaderText="LastName" SortExpression="LastName" />

<asp:BoundField DataField="Age" HeaderText="Age" SortExpression="Age" />

</Columns>

</asp:GridView>

<asp:LinqDataSource ID="LinqDataSource1" runat="server" ContextTypeName="QueryExtenderApp.DataClasses1DataContext"

EntityTypeName="" TableName="Employees">

</asp:LinqDataSource>

<br />

<asp:QueryExtender ID="QueryExtender1" runat="server" TargetControlID="LinqDataSource1">

<asp:SearchExpression DataFields="FirstName" SearchType="StartsWith">

<asp:ControlParameter ControlID="TextBox1" />

</asp:SearchExpression>

</asp:QueryExtender>

</div>

</center>

</form>

</body>

</html>

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

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

namespace QueryExtenderApp

{

public partial class WebForm1 : System.Web.UI.Page

{

protected void Page_Load(object sender, EventArgs e)

{

}

}

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

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

I hope this article was useful for you.