Basic on DOT Net: Searching XML file using ASP.NET and C#

I have found how to search a particular element from the XML file.

The XML file is:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<company>
<employee id="109">
<fname>John</fname>
<lname>Graph</lname>
<age>28</age>
</employee>
<employee id="110">
<fname>Anna</fname>
<lname>Laoe</lname>
<age>32</age>
</employee>
<employee id="111">
<fname>Ashley</fname>
<lname>Kazzl</lname>
<age>34</age>
</employee>
<employee id="113">
<fname>Greg</fname>
<lname>Muray</lname>
<age>24</age>
</employee>
<employee id="114">
<fname>Fannie</fname>
<lname>Dow</lname>
<age>36</age>
</employee>
</company>

The code to search the particular employee record from the existing xml file is as follows:
(I don't know if this is a better way to search a XML file, so plz. help me in optimizing the code)

string empid1 = Request.QueryString["empid"];
 Response.Write(" XML file searching using asp.net ");
 XmlDocument doc = new XmlDocument();

 string xmlFile = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/emp.xml");
 doc.Load(xmlFile);
 int empid=int.Parse(empid1);// convert the empid1 to int

 XmlNodeList xmlnode = doc.GetElementsByTagName("employee");
 for (int i = 0; i < xmlnode.Count; i++)
 {

 XmlAttributeCollection xmlattrc = xmlnode[i].Attributes;
 if (int.Parse(xmlattrc[0].Value) == empid)
 {
 Response.Write(" Employee-ID: " + xmlattrc[0].Value);
 Response.Write(" First Name: " + xmlnode[i].ChildNodes[0].InnerText);
 Response.Write(" Last Name: " + xmlnode[i].ChildNodes[1].InnerText);
 Response.Write(" Age: " + xmlnode[i].ChildNodes[2].InnerText);
 Response.Write(" ");
 }
 }

Second Case
----------------
I got the solution to Update the data for a Particular Node (in this case to update the data of particular Employee)
I am pasting the complete C# file of that page

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

public partial class xml1 : System.Web.UI.Page
{
 protected void Page_Load(object sender, EventArgs e)
 {
//Page_Load will just grab the Employee-Id of particular Employee and will search for that EmployeeID in the XML file. If it find a appropriate match then it will
//display all the Details of that Employee viz. Empid(Empid is not editable), First Name(editable), Last Name(editable), Age(editable)
 if (!IsPostBack)
 {
 string empid1 = Request.QueryString["empid"];
 // Response.Write(empid1); WF
 // Response.Write(" XML file searching using asp.net ");
 XmlDocument doc = new XmlDocument();

 string xmlFile = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/emp.xml");
 doc.Load(xmlFile);
 int empid = int.Parse(empid1);

 XmlNodeList xmlnode = doc.GetElementsByTagName("employee");
 for (int i = 0; i < xmlnode.Count; i++)
 {

 XmlAttributeCollection xmlattrc = xmlnode[i].Attributes;
 if (int.Parse(xmlattrc[0].Value) == empid)
 {
 lblEmpid.Text = xmlattrc[0].Value;
 txtFirstName.Text = xmlnode[i].ChildNodes[0].InnerText; //Assign First Name from XML file to txtFirstName Text Box
 txtLastName.Text = xmlnode[i].ChildNodes[1].InnerText; //Assign Last Name from XML file to txtLastName Text Box
 txtAge.Text = xmlnode[i].ChildNodes[2].InnerText;// //Assign Age from XML file to txtAge Text Box

 }
 }

 }
 }
 protected void Button1_Click(object sender, EventArgs e)
 {
 //This Code will Update the XML file and will replace the data in the Xmlnode.
 // We can change the First Name, Last Name , Age of a PArticular Employee by using this code.
 string empid1 = lblEmpid.Text.ToString();
 XmlDocument doc = new XmlDocument();
 string fname = txtFirstName.Text;
 string lname = txtLastName.Text;
 string age = txtAge.Text;
 string xmlFile = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/emp.xml");
 doc.Load(xmlFile);
 int empid = int.Parse(empid1);

 XmlNodeList xmlnode = doc.GetElementsByTagName("employee");
 for (int i = 0; i < xmlnode.Count; i++)
 {

 XmlAttributeCollection xmlattrc = xmlnode[i].Attributes;
 if (int.Parse(xmlattrc[0].Value) == empid)
 {


 xmlnode[i].ChildNodes[0].InnerText = fname;//ChildNodes[0] is First Name
 xmlnode[i].ChildNodes[1].InnerText = lname;
 xmlnode[i].ChildNodes[2].InnerText = age;
 doc.Save(xmlFile);// The New Data is Saved in the XML file by replacing old data for that particular employee.
 }
 }
 }
}

Case 3
--------
Instead of looping each employee for get a particular employee using ID, we can use XPath.
You can change the following code

XmlNodeList xmlnode = doc.GetElementsByTagName("employee");
        for (int i = 0; i < xmlnode.Count; i++)
        {


            XmlAttributeCollection xmlattrc = xmlnode[i].Attributes;
            if (int.Parse(xmlattrc[0].Value) == empid)
            {
                
                
                xmlnode[i].ChildNodes[0].InnerText = fname;//ChildNodes[0] is First Name
                xmlnode[i].ChildNodes[1].InnerText = lname;
                xmlnode[i].ChildNodes[2].InnerText = age;
                doc.Save(xmlFile);// The New Data is Saved in the XML file by replacing old data for that particular employee.
            }
        }

AS (Which uses XPath)

XmlNodeList xmlnode = doc.SelectNodes("//employee[@id=" + empid + "]");
        for (int i = 0; i < xmlnode.Count; i++)   // Loops only once if record exists
        {


            //XmlAttributeCollection xmlattrc = xmlnode[i].Attributes;  //-- This Code is not needed
            //if (int.Parse(xmlattrc[0].Value) == empid) //-- This code is not needed
            //{
                
                
                xmlnode[i].ChildNodes[0].InnerText = fname;//ChildNodes[0] is First Name
                xmlnode[i].ChildNodes[1].InnerText = lname;
                xmlnode[i].ChildNodes[2].InnerText = age;
                doc.Save(xmlFile);// Even this line can be out of the for loop...
            //}
        }

CASE 3
---------
I got solution to add (append) an element to in the existing XML file at the end of file.
When I add the (employee) element to the end of the file , I search the last empid and increment it by 1 and then insert this current empid in the empid attribute of the current employee (element) being added to the end of the file.
Limitations: I cannot see if there are any duplicates. (but this xml file does not contain any mission critical data).
I am pasting the code in this section (Please advice if I can write my code in a better way [:)])

string fname, lname, age;
 fname = txtFirstName.Text.ToString();
 lname = txtLastName.Text.ToString();
 age = txtAge.Text.ToString();
 XmlDocument doc = new XmlDocument();
 string xmlFile = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/emp.xml");
 doc.Load(xmlFile);
 //First we have to get the empid of the last employee and increment it by 1 for the new employee
 XmlNodeList xmlnode = doc.GetElementsByTagName("employee");
 //Response.Write("<script type='text/javascript'>alert('" + xmlnode.Count + "')</javascript>");
 XmlNode empnode = doc.CreateElement("employee");
 // Response.Write(xmlnode.Count);//WF

 XmlAttributeCollection xmlattrc = xmlnode[xmlnode.Count-1].Attributes;

 //Response.Write(xmlattrc[0].Value);//WF



 int lastempid = int.Parse(xmlattrc[0].Value);//Get the Emp-Id of the last Employee
 int currempid = lastempid + 1;

 XmlNode empid = doc.CreateNode(XmlNodeType.Attribute, "id", "");
 empid.Value = currempid.ToString();

 empnode.Attributes.SetNamedItem(empid);
 XmlNode empfname = doc.CreateElement("fname");
 empfname.InnerText = fname;
 empnode.AppendChild(empfname);
 XmlNode emplname = doc.CreateElement("lname");
 emplname.InnerText = lname;
 empnode.AppendChild(emplname);
 XmlNode empage = doc.CreateElement("age");
 empage.InnerText = age;
 empnode.AppendChild(empage);
 doc.DocumentElement.AppendChild(empnode);
 doc.Save(xmlFile);

/////////////////

The XML file after New data is added:

<?xml version="1.0" encoding="ISO-8859-1"?>
<company>
<employee id="109">
 <fname>John</fname>
 <lname>Graph</lname>
 <age>28</age>
</employee>
<employee id="110">
 <fname>Anna</fname>
 <lname>Laoe</lname>
 <age>32</age>
</employee>
<employee id="111">
 <fname>Allan</fname>
 <lname>Woods</lname>
 <age>25</age>
</employee>
<employee id="113">
 <fname>Greg</fname>
 <lname>Muray</lname>
 <age>24</age>
</employee>
<employee id="114">
 <fname>Fannie</fname>
 <lname>Dow</lname>
 <age>36</age>
</employee>
<employee id="115">
 <fname>Hello</fname>
 <lname>World</lname>
 <age>11</age>
</employee>
<employee id="116">
 <fname>Hello</fname>
 <lname>World</lname>
 <age>11</age>
</employee>
</company>

Still I have to write the code to delete a particular node (employee) from the XML File.

CASE 4
----
I found the Solution for deleting a particular node (employee). from the XML file :
the employee node is deleted by first getting its empid and then deleting all the information associated with that empid(like fname,lname,age)

Following is the code:

string fname, lname, age;
 fname = txtFirstName.Text.ToString();
 lname = txtLastName.Text.ToString();
 age = txtAge.Text.ToString();
 string empid1 =Request.Querystring["empid"]; // the empid is passed in the querystring
 XmlDocument doc = new XmlDocument();
 string xmlFile = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/emp.xml");
 doc.Load(xmlFile);
 int empid = int.Parse(empid1);
 XmlNode deletenode = doc.SelectSingleNode("//employee[@id=" + empid + "]");
 deletenode.ParentNode.RemoveChild(deletenode); //In this line all the information (i.e. child node) of employee are deleted.
 doc.Save(xmlFile);
(Please suggest if I can do the same thing in a better manner)

http://forums.asp.net/t/1318271.aspx/1

Basic on DOT Net

Monday, April 25, 2011

Searching XML file using ASP.NET and C#

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