Create XML Nodes based on XPath?

Question

Does anyone know of an existing means of creating an XML hierarchy programatically from an XPath expression?

For example if I have an XML fragment such as:

<feed>     <entry>         <data></data>         <content></content>     </entry> </feed> 

Given the XPath expression /feed/entry/content/@source I would have:

<feed>     <entry>         <data></data>         <content @source=""></content>     </entry> </feed> 

I realize this is possible using XSLT but due to the dynamic nature of what I'm trying to accomplish a fixed transformation won't work.

I am working in C# but if someone has a solution using some other language please chime in.

Thanks for the help!

Answer 1

In the example you present the only thing being created is the attribute ...

XmlElement element = (XmlElement)doc.SelectSingleNode("/feed/entry/content"); if (element != null)     element.SetAttribute("source", ""); 

If what you really want is to be able to create the hierarchy where it doesn't exist then you could your own simple xpath parser. I don't know about keeping the attribute in the xpath though. I'd rather cast the node as an element and tack on a .SetAttribute as I've done here:

 static private XmlNode makeXPath(XmlDocument doc, string xpath) {     return makeXPath(doc, doc as XmlNode, xpath); }  static private XmlNode makeXPath(XmlDocument doc, XmlNode parent, string xpath) {     // grab the next node name in the xpath; or return parent if empty     string[] partsOfXPath = xpath.Trim('/').Split('/');     string nextNodeInXPath = partsOfXPath.First();     if (string.IsNullOrEmpty(nextNodeInXPath))         return parent;      // get or create the node from the name     XmlNode node = parent.SelectSingleNode(nextNodeInXPath);     if (node == null)         node = parent.AppendChild(doc.CreateElement(nextNodeInXPath));      // rejoin the remainder of the array as an xpath expression and recurse     string rest = String.Join("/", partsOfXPath.Skip(1).ToArray());     return makeXPath(doc, node, rest); }  static void Main(string[] args) {     XmlDocument doc = new XmlDocument();     doc.LoadXml("<feed />");      makeXPath(doc, "/feed/entry/data");     XmlElement contentElement = (XmlElement)makeXPath(doc, "/feed/entry/content");     contentElement.SetAttribute("source", "");      Console.WriteLine(doc.OuterXml); }