Navigating XML information items using ASP.NET 2.0 and C#

This tutorial will show you how to navigate XML information items in ASP.NET 2.0 using C#.

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First, import the namespace of System.XML and System.XML.XPath

The System.Xml.XPath namespace contains the classes that define a cursor model for navigating and editing XML information items as instances of the XPath 2.0 Data Model. In this sample, we will use the classes of XPathDocument, XPathNavigator, XPathExpression and XPathNodeIterator under this namespace .

using System.Xml;
using System.Xml.XPath

The Button1_Click event is to perform the navgating XML infomration items fuction. The results will be displayed in the textbox. There are 4 classes we applied.

XPathDocument: Provides a fast, read-only, in-memory representation of an XML document using the XPath data model.

XPathNavigator: Provides a cursor model for navigating XML data.

XPathExpression: Provides a typed class that represents a compiled XPath expression.

XPathNodeIterator: Provides an iterator over a selected set of nodes.

XPathDocument doc = new XPathDocument(Server.MapPath("Demo.xml"));
XPathNavigator nav = doc.CreateNavigator();

XPathExpression xpathExpress = nav.Compile("//bk:Book[position()"
+this.ddownlist.SelectedValue.Trim()+this.txtNum.Text.Trim()+"]");
//use AddNamespace
XmlNamespaceManager xmlManager = new XmlNamespaceManager(nav.NameTable);
xmlManager.AddNamespace("bk", "http://myserver/myschemas/Books");
xpathExpress.SetContext(xmlManager);

XPathNodeIterator xIterator = nav.Select(xpathExpress);
this.TextBox1.Text = "";
this.TextBox1.ForeColor = System.Drawing.Color.Empty;
while (xIterator.MoveNext())

this.TextBox1.Text = this.TextBox1.Text + "\r\n" + xIterator.Current.Value;

if (xIterator.Count.Equals(0))
{

this.TextBox1.Text = "There is no xml data in the condition.";
this.TextBox1.ForeColor = System.Drawing.Color.Red;

}
xmlManager = null;
nav = null;
doc = null;

The contents of Demo.xml:

<?xml version='1.0' encoding='utf-8'?>
<bk:Books xmlns:bk='http://myserver/myschemas/Books'>

<bk:Book>

<bk:Title>Just XML</bk:Title>

</bk:Book> <bk:Book>

<bk:Title>Professional XML</bk:Title>

</bk:Book> <bk:Book>

<bk:Title>XML Step by Step</bk:Title>

</bk:Book> <bk:Book>

<bk:Title>XML By Example</bk:Title>

</bk:Book>

</bk:Books>

The front end Default.aspx page looks something like this:

<body>

<fieldset><legend>Select xml data with XPath</legend>

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" CellPadding="4"
Font-Size="Smaller" ForeColor="#333333" GridLines="None" RowHeaderColumn="Title"
Width="205px">

</asp:GridView> <br />

<asp:Label ID="Label1" runat="server" Text="Select Item Position:"></asp:Label> <asp:DropDownList
ID="ddownlist" runat="server">

<asp:ListItem><</asp:ListItem>
<asp:ListItem><=</asp:ListItem>
<asp:ListItem>></asp:ListItem>
<asp:ListItem>>=</asp:ListItem>

</asp:DropDownList>

<asp:TextBox ID="txtNum" runat="server" Width="57px">2</asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtNum"
ErrorMessage="Please input integer number."></asp:RequiredFieldValidator><br />
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Search" /><br />
<asp:TextBox ID="TextBox1" runat="server" Height="88px" TextMode="MultiLine" Width="237px"></asp:TextBox>

</fieldset>

</div>
</form>

</body>

The flow for the code behind page as follows.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.Xml;
using System.Xml.XPath;
public partial class _Default : System.Web.UI.Page
{

protected void Page_Load(object sender, EventArgs e)
{

DataSet myDs = new DataSet();
myDs.ReadXml(Server.MapPath("Demo.xml"));
this.GridView1.DataSource = myDs;
this.GridView1.DataBind();

}
protected void Button1_Click(object sender, EventArgs e)
{

this.TextBox1.Text = this.TextBox1.Text + "\r\n" + xIterator.Current.Value;

if (xIterator.Count.Equals(0))
{

this.TextBox1.Text = "There is no xml data in the condition.";
this.TextBox1.ForeColor = System.Drawing.Color.Red;

}
xmlManager = null;
nav = null;
doc = null;

}

Download the Full Working Version of this Project written with Visual Studio.NET C# 2005 Here!

Looking for the VB.NET 2005 Version? Click Here!

Looking for more ASP.NET Tutorials? Click Here!