XML Manipulation using .NET (C#) PART I

Hello folks,
In this article I'm going to discuss how to
1. Create an XML file
2. Modify an XML elements using XPath
3. Bind an XML document to Data Grid View
4. Delete an XML node using Xpath

In the Part II, I will discuss how to
1. Search XML elements and display searched result in Data Grid View using LINQ.

Please note: Please use Firefox or IE to read this article.Sorry for the inconvenience caused.

I'm gonna create and use following XML file throughout this article.

  
    
    J K. Rowling
    2005
    29.99
    CHILDREN
  
  
    
    Giada De Laurentiis
    2005
    30.00
    COOKING
  
  
    
    James McGovern
    2010
    49.99
    WEB
  

First of all let's define the file path of our XML file in the web config file and create a class called XMLManager to get the file path.
The reason for this step is to keep the file path in a specific place and access it from anywhere from the application.
Insert the following code under configuration section in web config file.

The XML file we are going to create is bookDetails.xml and it locates in a folder called XML.
Here's the XMLManager class. In here I use a static method because in order to use the method we don't have to create an instance of the class.

public class XMLManager
    {
        public static string GetFilePath()
        {
            return ConfigurationManager.AppSettings["XmlFilePath"].ToString();
        }
    }

Create an XML Document
Following code snippet shows how to create above XML file using XMLDocument class.
In order to use below code you have import System.XML base class

private void writeXML()
        {
            // Create new XML document
            XmlDocument doc = new XmlDocument();

            // Create nodes and attributes
            XmlNode bookstore, book, title, author, year, price, category;
            XmlAttribute id;

            //  the root element
            bookstore = doc.CreateElement("bookstore");
            doc.AppendChild(bookstore);

            //  element with category attribute
            book = doc.CreateElement("book");            
            bookstore.AppendChild(book);
            id = doc.CreateAttribute("id");
            id.Value = getNewBookID().ToString();
            book.Attributes.Append(id);

            //