How to get latest node details by using xmldocument?

Question

I have xml file like following.

<Root>
      <Main Name="Install">
        <Details>Success</Details>
        <Maintain>Install period</Maintain>
      </Main>
    <Main Name="Uninstall">
        <Details>failure</Details>
        <Maintain>uninstall period</Maintain>
      </Main>
     <Main Name="Discard">
        <Details>failure</Details>
        <Maintain>discard period</Maintain>
      </Main>
     <Main Name="Install">
        <Details>Done</Details>
        <Maintain>Got Output</Maintain>
      </Main>
    </Root>

I need only last latest update to print in xml.

I've used following xdocument(using system.xml.Linq) code and found output.

XDocument xDoc1 = XDocument.Load(@"C:\Input.xml");

var elemsNew = xDoc1.Element("Root").Elements("Main")
    .GroupBy(x => x.Attribute("Name").Value)
    .Select(g => g.Last())
    .ToArray();

XDocument xDoc2 = new XDocument(new XElement("Root", elemsNew));
xDoc2.Save(@"C:\Output.xml");

The output came like following:

<Root>
 <Main Name="Uninstall">
   <Details>failure</Details>
    <Maintain>uninstall period</Maintain>
 </Main>
 <Main Name="Discard">
    <Details>failure</Details>
    <Maintain>discard period</Maintain>
 </Main>
<Main Name="Install">
    <Details>Done</Details>
    <Maintain>Got Output</Maintain>
 </Main>
</Root>

But instead of using xdocument Is there any option by getting this output by xmldocument(using system.xml)? I need output only by xmldocument.

Answer 1

You can do it manually. Just iterate through your Main elements from the end to beginning, removing any items which Name attribute has already been met.

var document = new XmlDocument();
document.LoadXml(xmlString);

Dictionary<string, bool> used = new Dictionary<string, bool>();

var allNodes = document.SelectNodes("Root/Main");

for (int i = allNodes.Count - 1; i >= 0; i--)
{
    var name = ((XmlElement)allNodes[i]).GetAttribute("Name");

    if (used.ContainsKey(name))
    {
        allNodes[i].ParentNode.RemoveChild(allNodes[i]);
    }
    else
    {
        used.Add(name, true);
    }
}

Console.WriteLine(document.OuterXml);

Here is the working IDEOne demo.

However, as I already mentioned in comments, it is a really good idea to use XDocument, because it is much more convenient, and it is modern.