命名空间遍历

Question

I am trying to parse the following sample piece of XML:

<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <soapenv:Body>
        <d2LogicalModel modelBaseVersion="1.0" xmlns="http://datex2.eu/schema/1_0/1_0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://datex2.eu/schema/1_0/1_0 http://datex2.eu/schema/1_0/1_0/DATEXIISchema_1_0_1_0.xsd">
            <payloadPublication xsi:type="PredefinedLocationsPublication" lang="en">
                <predefinedLocationSet id="GUID-NTCC-VariableMessageSignLocations">
                    <predefinedLocation id="VMS30082775">
                        <predefinedLocationName>    
                            <value lang="en">VMS M60/9084B</value>
                        </predefinedLocationName>
                    </predefinedLocation>
                </predefinedLocationSet>
            </payloadPublication>
        </d2LogicalModel>
    </soapenv:Body>
</soapenv:Envelope>

I specifically need to get at the contents of the top-level predefinedLocation tag. By my calculations, the correct XPath should be

/soapenv:Envelope/soapenv:Body/d2LogicalModel/payloadPublication/predefinedLocationSet/predefinedLocation

I am using the following C# code to parse the XML: string filename = "content-sample.xml";

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

        XmlNamespaceManager nsmanager = new XmlNamespaceManager(xmlDoc.NameTable);
        nsmanager.AddNamespace("soapenv", "http://schemas.xmlsoap.org/soap/Envelope");

        string xpath ="/soapenv:Envelope/soapenv:Body/d2LogicalModel/payloadPublication/predefinedLocationSet/predefinedLocation";
        XmlNodeList itemNodes = xmlDoc.SelectNodes(xpath, nsmanager);

However, this keeps coming up with no results. Can anyone shed any light on this, because I feel like I'm banging my head on a brick wall.

Answer 1

d2LogicalModel and its descendants are not in the empty namespace but in the "http://datex2.eu/schema/1_0/1_0" namespace. You need to add this namespace to the namespace manager to be able to select your elements:

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

XmlNamespaceManager nsmanager = new XmlNamespaceManager(xmlDoc.NameTable); 
nsmanager.AddNamespace("soapenv", "http://schemas.xmlsoap.org/soap/Envelope"); 
nsmanager.AddNamespace("dataexNs", "http://datex2.eu/schema/1_0/1_0"); 


string xpath ="/soapenv:Envelope/soapenv:Body/dataexNs:d2LogicalModel/dataexNs:payloadPublication/dataexNs:predefinedLocationSet/dataexNs:predefinedLocation"; 
XmlNodeList itemNodes = xmlDoc.SelectNodes(xpath, nsmanager); 

Even if you are using Linq to Xml it's worth using fully qualified names to not select something that happens to have the same local name.

Answer 2

If you want to avoid dealing with namespaces (using Linq2Xml)

var xDoc = XDocument.Load(.....);

var loc = xDoc.Root.Descendants2("predefinedLocation").First();
var id = loc.Attribute("id");
var value = loc.Descendants2("value").First().Value;


public static class S_O_Extensions
{
    public static IEnumerable<XElement> Descendants2(this XElement xRoot, string name)
    {
        return xRoot.Descendants().Where(n => n.Name.LocalName == name);
    }
}

Answer 3

I guess this LINQ2XML would help u out

XElement doc = XElement.Load("yourStream.xml");
XNamespace s="http://datex2.eu/schema/1_0/1_0";

foreach (var itm in doc.Descendants(s+ "predefinedLocation"))
{
itm;//your required predefinedLocationName node 
itm.Element(s+"predefinedLocationName").Element(s+"value").Value;//VMS M60/9084B
}

Answer 4

When it comes to XPath, I always find that smaller/shorter/simpler XPath expressions are better. I would use this:

//predefinedLocationSet

How's that work for you? It certainly does the trick for me on an XPath tester.