Need help in adding a new XML node

Question

<?xml version="1.0" encoding="utf-8"?>
<mappings>
  <mapping>
    <aID iskey="true">ABC</aID>
    <bID iskey="true">DEF</bID>
    <SubAccount>PS</SubAccount>
    <Account>PS</Account>
  </mapping>
  <mapping>
    <aID isKey="true">GHI</aID>
    <bID isKey="true">PFP</bID>
    <SubAccount>MS</SubAccount>
    <!-- I want to add a new node here, how can I do this  -->
  </mapping>
  <mapping>
    <aID isKey="true">MNO</aID>
    <bID isKey="true">BBG</bID>
    <SubAccount>MAX</SubAccount>
  </mapping>
</mappings>

I want to add a new node as mentioned in the above XML. I tried a lot but I could not succeed.

XmlDocument xDoc = new XmlDocument();
xDoc.Load(filename);

foreach (XmlNode node in xmlDoc.SelectNodes("/mappings/mapping"))
{
    if (boothIDNode.InnerXml == BoothID)
    {
        chkBoothIDExists = true;
        if (clientIDNode.InnerText == ClientID)
        {
            chkClientIDExists = true;
            for (int j = 2; j < nodelist.Count; j++)
            {
                columnNode = nodelist[j];
                if (columnNode.Name == column.ToString())
                {
                    XmlNode elm = xDoc.CreateNode(XmlNodeType.Element,"Account",null);
                    elm.InnerText = value.ToString();                                                                                 
                    node.AppendChild(elm);  //  Error comes here 
                }
            }
        }
    }   
}

xmlDoc.Save(filename);  

The question is solved. The problem occured due to my silly mistake. Basically there are two xml documnets and I'm creating a new node of other xml documnet due to which the error cames. THanks all, XmlDocument xDoc = new XmlDocument(); XmlDocument xmlDoc = new XmlDocument();

ERROR: The node to be inserted is from a different document context

Answer 1

Use something like this, not ac# person but this should help. I think insertafter is what you need:

  XmlNode currNode = xDoc.SelectNodes("/mappings/mapping");  
  XmlNode elm = xDoc.CreateNode(XmlNodeType.Element,"Account",null);
  currNode.InsertAfter(elm, currNode.LastChild);

Answer 2

In order to add a node, consider this example:

              XDocument a = XDocument.Parse(@"<?xml version=""1.0"" encoding=""utf-8""?>
<mappings>
  <mapping>
    <aID iskey="true">ABC</aID>
    <bID iskey="true">FPP</bID>
    <SubAccount>PS</SubAccount>
    <Account>PS</Account>
  </mapping>
  <mapping>
    <aID isKey="true">GHI</aID>
    <bID isKey="true">PFP</bID>
    <SubAccount>MS</SubAccount>
    <!-- I want to add a new node here, how can I do this  -->
  </mapping>
  <mapping>
    <aID isKey="true">MNO</aID>
    <bID isKey="true">BBG</bID>
    <SubAccount>MAX</SubAccount>
  </mapping>
</mappings>");
a.Descendants("mapping").Skip(1).First().Add(new XElement("aaa", new XAttribute("id", 1)));

--->

      <mappings>
  <mapping>
    <aID iskey="true">ABC</aID>
    <bID iskey="true">FPP</bID>
    <SubAccount>PS</SubAccount>
    <Account>PS</Account>
  </mapping>
  <mapping>
    <aID isKey="true">GHI</aID>
    <bID isKey="true">PFP</bID>
    <SubAccount>MS</SubAccount>
    <!-- I want to add a new node here, how can I do this  -->
    <aaa id="1" />
  </mapping>
  <mapping>
    <aID isKey="true">MNO</aID>
    <bID isKey="true">BBG</bID>
    <SubAccount>MAX</SubAccount>
  </mapping>
</mappings>

Answer 3

XDocument doc = XDocument.Load(filepath); // filepath is string
doc.Element(firstnodename).SetElementValue(descendantname,newvalue); //names and value are string
doc.Save(filepath); // This line optional. And filepath like : @"C:\Users\user\desktop\a.xml" or "C:\\Users\\user\\desktop\\a.xml". You should write with ".

You can write longer .Element ForEx:

doc.Element(firstnode).Element(secondnode).Element(thirdnode).SetElementValue(fourthnode,valueoffourth);