How to search & modify within XML documents using XPath queries

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Introduction

This article is intended to show you how XPath queries have made programmers’ life easier regarding XML data manipulation. XML applications have many varieties; from simple client-side and server-side applications to web services over the Internet. However, one particular fact never changes; Data change dynamically and constantly. In this simple and short newcomer's project we will search for data within an XML document using two different XPath queries. Also, we will add a method to replace current information with new information. Since this is my first article regarding Microsoft C# and XML there might be some points which, need modification or improvement so please contact me to share your ideas or any suggestions you may have. Personally, I like to write every project from scratch! in this case, read the following steps:

Create a new project:

1 - Launch Visual Studio.Net IDE and select “Windows Application” under Visual C# Projects. Of course, you can select "Console Application" only it requires you to modify part of the source code.

2 - The controls, which, we would need are TreeView , Edit-Box, List-Box, Button & Label controls.

3 - First, let's consider the Nampespaces, which are necessary to include:

3 -1 ) System.Xml

3-2 ) System.Xml.Xpath

3-3 ) System.Text

3-4 ) System.Collections.Specialized //Was used for holding Node paths and Node attributes but I removed them to make the code smaller

Note: Please ignore System.Collections.Specialized.

4 - Define a sturcutre as below:

struct TXN 
{
   public TreeNode nnode;
   public XmlNode xnode;
   public TXN(TreeNode nnode, XmlNode xnode)
  {
    this.nnode = nnode;
    this.xnode = xnode;
   }
}

5 - Also, I did name the controls as:

private System.Winodws.Forms.GroupBox treeGroupBox;
private System.Winodws.Forms.TreeView treeXmlBody;
private System.Winodws.Forms.Button btnOpenXml;
private System.Winodws.Forms.Button btnReplace;
private System.Winodws.Forms.Button btnClose;
private System.Winodws.Forms.Label lblItem; //The item we would looking for
private System.Winodws.Forms.Label lblPath; 
private System.Winodws.Forms.ListBox listBoxPaths; 
private System.Winodws.Forms.TextBox txtItem; 
private System.Winodws.Forms.Button btnSearch;
private System.Winodws.Forms.TextBox txtReplace; //The text which should 
                                                 //replace the previous text

public string sXPathQuery; //Holds XPath query
public string sPath; //Keeps track of working area

private XmlDocument xdoc; //XML object

- For more information please refer to comments or contact me. Once again, thanks for reading the article.

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