如何在C＃中选择带有XPath的节点？

Question

Simple question, I just want to select the text from the <Template> tag. Here's what I have, but the Xpath doesn't match anything.

public static void TestXPath()
{
    string xmlText = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>";
    xmlText += "<Properties xmlns=\"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties\" xmlns:vt=\"http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes\">";
    xmlText += "<Template>Normal</Template>  <TotalTime>1</TotalTime>  <Pages>1</Pages>  <Words>6</Words>";
    xmlText += "</Properties>";

    XmlDocument xmlDoc = new XmlDocument();
    xmlDoc.Load(new System.IO.StringReader(xmlText));

    foreach (XmlNode node in xmlDoc.SelectNodes("//Template"))
    {
        Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
    }
}

Answer 1

You need to use an XmlNamespaceManager because the Template element is in a namespace:

XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(new System.IO.StringReader(xmlText));
XmlNamespaceManager manager = new XmlNamespaceManager(xmlDoc.NameTable);
manager.AddNamespace("ns", 
    "http://schemas.openxmlformats.org/officeDocument/2006/extended-properties");

foreach (XmlNode node in xmlDoc.SelectNodes("//ns:Template", manager))
{
    Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}

Answer 2

That is a namespace issue; you need to get the name-table, pick an alias, and use that in your query. Or perhaps (in this case) try GetElementsByTagName .

XmlNamespaceManager mgr = new XmlNamespaceManager(xmlDoc.NameTable);
mgr.AddNamespace("x",
    "http://schemas.openxmlformats.org/officeDocument/2006/extended-properties");
foreach (XmlNode node in xmlDoc.SelectNodes("//x:Template", mgr))
{
    Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}

Or:

foreach (XmlNode node in xmlDoc.GetElementsByTagName("Template"))
{
    Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
}

Answer 3

Here your xpath expression requires a namespace resolution. you have to instanciate a XmlNamespaceManager and use it in your SelectNodes.

this sample should work

    public static void TestXPath()
    {
        string xmlText = "<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"yes\"?>";
        xmlText += "<Properties xmlns=\"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties\" xmlns:vt=\"http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes\">";
        xmlText += "<Template>Normal</Template>  <TotalTime>1</TotalTime>  <Pages>1</Pages>  <Words>6</Words>";
        xmlText += "</Properties>";

        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.Load(new System.IO.StringReader(xmlText));

        XmlNamespaceManager nsmgr = new XmlNamespaceManager(xmlDoc.NameTable);
        nsmgr.AddNamespace("res", "http://schemas.openxmlformats.org/officeDocument/2006/extended-properties");

        foreach (XmlNode node in xmlDoc.SelectNodes("//res:Template", nsmgr))
        {
            Console.WriteLine("{0}: {1}", node.Name, node.InnerText);
        }
    }

you can also get the default namespace by using and write

string s = xmlDoc.DocumentElement.GetNamespaceOfPrefix("");
nsmgr.AddNamespace("ns", s);

Answer 4

Why do you need the namespace here anyway? just get rid of these

xmlns=\"http://schemas.openxmlformats.org/officeDocument/2006/extended-properties\" 
xmlns:vt=\"http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes\"

and your selection will work.