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("<br>XML file searching using asp.net<br><br>");
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("<br>Employee-ID: " + xmlattrc[0].Value);
Response.Write("<br>First Name: " + xmlnode[i].ChildNodes[0].InnerText);
Response.Write("<br>Last Name: " + xmlnode[i].ChildNodes[1].InnerText);
Response.Write("<br>Age: " + xmlnode[i].ChildNodes[2].InnerText);
Response.Write("<br>");
}
}
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("<br>XML file searching using asp.net<br><br>");
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
