Question

Below code is the function to Append a customerRecord in the Xml file.
I’ve got 2 questions here:

1.When I append a record, how to check whether the value of id and Mobile is already existing in the XML??
2.How to search a customer by id or by Mobile and display the values in the textboxes??

private const string FileName = @"C:\test\Person.xml";

private void button1_Click(object sender, EventArgs e)
{    
    var xmlDoc = new XmlDocument();

    xmlDoc.Load(FileName);

    var subRoot = xmlDoc.CreateElement("Customer");
    subRoot.SetAttribute("id", textBox6.Text.Trim());

    var firstName = xmlDoc.CreateElement("FirstName");
    var xmlTextUserName = xmlDoc.CreateTextNode(textBox1.Text.Trim());
    firstName.AppendChild(xmlTextUserName);
    subRoot.AppendChild(firstName);
    if (xmlDoc.DocumentElement != null) 
        xmlDoc.DocumentElement.AppendChild(subRoot);

    var email = xmlDoc.CreateElement("LastName");
    var xmlTextEmail = xmlDoc.CreateTextNode(textBox2.Text.Trim());
    email.AppendChild(xmlTextEmail);
    subRoot.AppendChild(email);
    if (xmlDoc.DocumentElement != null) 
        xmlDoc.DocumentElement.AppendChild(subRoot);

    var mobile = xmlDoc.CreateElement("Mobile");
    var xmlTextMobile = xmlDoc.CreateTextNode(textBox3.Text.Trim());
    mobile.AppendChild(xmlTextMobile);
    subRoot.AppendChild(mobile);
    if (xmlDoc.DocumentElement != null)
        xmlDoc.DocumentElement.AppendChild(subRoot);

    var address = xmlDoc.CreateElement("Address");
    var xmlTextAddress = xmlDoc.CreateTextNode(textBox4.Text.Trim());
    address.AppendChild(xmlTextAddress);
    subRoot.AppendChild(address);
    if (xmlDoc.DocumentElement != null) 
        xmlDoc.DocumentElement.AppendChild(subRoot);

    var country= xmlDoc.CreateElement("Country");
    var xmlTextCountry = xmlDoc.CreateTextNode(textBox5.Text.Trim());
    country.AppendChild(xmlTextCountry);
    subRoot.AppendChild(country);
    if (xmlDoc.DocumentElement != null)
        xmlDoc.DocumentElement.AppendChild(subRoot);

    xmlDoc.Save(FileName);
    if (File.Exists(FileName)) 
        return;

    var textWritter = new XmlTextWriter(FileName, null);
    textWritter.WriteStartDocument();
    textWritter.WriteStartElement("CustomerRecord");
    textWritter.WriteEndElement();
    textWritter.Close();
}
//Search by id or by Mobile
private void button3_Click(object sender, EventArgs e)
{

}

Sample XML:

<CustomerRecord>
  <Customer id="6786">
    <FirstName>khkjh</FirstName>
    <LastName>jkhjkh</LastName>
    <Mobile>887897</Mobile>
    <Address>jk</Address>
    <Country>fdgfdg</Country>
  </Customer>
</CustomerRecord>

Answer 1

There are number of ways (DataSet/DataTable, DOM,XmlSerialization) to parse (read/search/manipulate) the XML document but I’d like to suggest LINQ-XML.

XDocument doc = XDocument.Load(file);

string id="21";
XElement element = doc.Descendants("Customer")
                   .Where(p => p.Attribute("id").Value == id).FirstOrDefault();
if (element != null)
 {
  //found
   string firstName = (string)element.Element("FirstName");
   string mobile = (string)element.Element("Mobile");
 }
else
 {
  //Not found
  //To add a customer
   var ele = new XElement("Customer");
   ele.SetAttributeValue("id", id);
   ele.Add(new XElement("FirstName", firstName));
   ele.Add(new XElement("Mobile",mobile));
   doc.Root.Add(ele);
   doc.Save(file);
 }