Joins Using LINQ-to-XML

Introduction

Today, in this article let's play around with one of the interesting and most useful concept in XML.

Question: What are joins using LINQ-to-XML?

In simple terms "It enables perform a join between two XML files and retrieve the value into grid as a result set".

Step 1: Create a new WebForm project

Step 2: The complete code of Employee.xml looks like this:

<?xml version="1.0" encoding="utf-8" ?>

<FirstName>Vijay</FirstName>

<LastName>Prativadi</LastName>

</Employee>

<FirstName>Swetha</FirstName>

<LastName>Prativadi</LastName>

</Employee>

<LastName>Reddy</LastName>

</Employee>

</Employees>

Step 3: The complete code of Department.xml looks like this:

<?xml version="1.0" encoding="utf-8" ?>

<DepartmentName>Admin</DepartmentName>

</Department>

</Department>

</Department>

</Departments>

Step 4: The complete code WebForm1.aspx looks like this:

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

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

.grid

{

margin-top: 50px;

}

</style>

</head>

<body>

<div>

<table>

<tr>

<asp:Label ID="Label1" runat="server" Text="Joins using LINQ-to-XML" Font-Bold="true"

Font-Size="Large" Font-Names="Verdana" ForeColor="Maroon"></asp:Label>

</td>

</tr>

<tr>

<asp:Button ID="Button1" runat="server" Text="Select Data" Font-Names="Verdana" Width="213px"

BackColor="Orange" Font-Bold="True" OnClick="Button1_Click" />

</td>

</tr>

<tr>

<asp:GridView ID="GridView1" runat="server" CssClass="grid" BackColor="LightGoldenrodYellow"

BorderColor="Tan" BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None">

</asp:GridView>

</td>

</tr>

</table>

</div>

</center>

</form>

</body>

</html>

Step 5: The complete code WebForm1.aspx.cs looks like this:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Xml.Linq;

namespace JoinsusingLINQtoXMLApp

{

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

{

protected void Page_Load(object sender, EventArgs e)

{

}

protected void Button1_Click(object sender, EventArgs e)

{

XElement department = XElement.Load(@"c:\users\administrator\documents\visual studio 2010\Projects\JoinsusingLINQtoXMLApp\JoinsusingLINQtoXMLApp\Department.xml");

XElement employee = XElement.Load(@"c:\users\administrator\documents\visual studio 2010\Projects\JoinsusingLINQtoXMLApp\JoinsusingLINQtoXMLApp\Employee.xml");

var joinQuery = from r in department.Descendants("Department")

join s in employee.Descendants("Employee") on (int)r.Attribute("EmpId") equals (int)s.Attribute("Id")

select new

{

EmpId = (int)s.Attribute("Id"),

FirstName = (string)s.Element("FirstName"),

LastName = (string)s.Element("LastName"),

Age = (int)s.Element("Age"),

DepartmentName = (string)r.Element("DepartmentName")

};

GridView1.DataSource = joinQuery;

GridView1.DataBind();

}

Step 6: The output of application looks like this

Step 7: The data retrieved output of application looks like this