Question

I need some help in returning an XmlDocument object from XPathNodeIterator.

Here is what I was trying to do:

public XmlDocument GetFilteredXML(XmlDocument baseXML, int codeID)
{
    XPathNavigator nav = baseXML.CreateNavigator();
    string xpath = /*some expression based on codeID*/;
    XPathExpression exp = nav.Compile(xpath);
    exp.AddSort(/*do some sorting*/);
    XPathNodeIterator iter = exp.Select(exp);

    // Here how do I return an XmlDocument object from
    // the iterator which contains the selected nodes only?
}

Answer 1

The XPathNodeIterator does not contain the nodes, exactly. The name is a clue – it is an iterator, which means it only contains the logic for how to iterate over the nodes you want. The nodes themselves come from somewhere else – in this case, the original baseXML object you provided. They never leave that object, you just created a navigator that knows how to navigate the document, and an iterator, which knows how to iterate the navigator using some criteria.

To do what you’re describing, you need to create a new XmlDocument, give it a new root element, and for each node from the iterator, call ImportNode and then Append. This will create a flat XmlDocument with all the selected nodes in the root element.