How to select child node with XPath

Question

I'm trying to get values from a XML document using the iXF format, but I'm having some issues with the XPath syntax.

I have the following XML document

<SOAP_ENV:Envelope xmlns:NS2="http://www.ixfstd.org/std/ns/core/classBehaviors/links/1.0" xmlns:NS1="CATIA/V5/Electrical/1.0" xmlns:tns="IXF_Schema.xsd" xmlns:ixf="http://www.ixfstd.org/std/ns/core/1.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP_ENV="http://schemas.xmlsoap.org/soap/envelope/" xsi:schemaLocation="IXF_Schema.xsd ElectricalSchema.xsd">
    <SOAP_ENV:Body>
        <ixf:object id="Electrical Physical System00000089.1" xsi:type="tns:Harness">
            <tns:Name>Electrical Physical System00000089.1</tns:Name>
        </ixf:object>
        <ixf:object id="X10(1)//X11(1)" xsi:type="tns:Wire">
            <tns:Name>X10(1)//X11(1)</tns:Name>
            <NS1:Wire>
                <NS1:Length>763,752mm</NS1:Length>
                <NS1:Color>RD</NS1:Color>
                <NS1:OuterDiameter>1,32mm</NS1:OuterDiameter>
            </NS1:Wire>
        </ixf:object>
    </SOAP_ENV:Body>
</SOAP_ENV:Envelope>

And i'm trying to find all the Wire objects and get the Name and Length values with the following code.

XmlDocument xlDocument = new XmlDocument();
xlDocument.Load(importFile);

XmlNamespaceManager nsManager = new XmlNamespaceManager(xlDocument.NameTable);
nsManager.AddNamespace("tns", "IXF_Schema.xsd");
nsManager.AddNamespace("xsi", "http://www.w3.org/2001/XMLSchema-instance");
nsManager.AddNamespace("ixf", "http://www.ixfstd.org/std/ns/core/1.0");
nsManager.AddNamespace("NS1", "CATIA/V6/Electrical/1.0");
nsManager.AddNamespace("NS2", "http://www.ixfstd.org/std/ns/core/classBehaviors/links/1.0");
             
//Get all wire objects
XmlNodeList wires = xlDocument.SelectNodes("descendant::ixf:object[@xsi:type = \"tns:Wire\"]", nsManager);

foreach (XmlNode wire in wires)
{
    string wireName;
    string wireLength;

    XmlNode node = wire.SelectSingleNode("./tns:Name", nsManager);
    wireName = node.InnerText;
    
    XmlNode node1 = wire.SelectSingleNode("./NS1:Wire/NS1:Length", nsManager);            
    wireLength = node1.InnerText;
}

I can get the wireName value without any problems but the Length element selection always returns 0 matches and I can not figure out why. I also tried to only select the Wire element using the same syntax as the Name element ./NS1:Wire but that also returns 0 matches.

score 2 · Accepted Answer · edited Nov 09 '22 at 15:10

Your XML declares

                    xmlns:NS1="CATIA/V5/Electrical/1.0"
                                     ^^

Your C# declares a different namespacem

nsManager.AddNamespace("NS1", "CATIA/V6/Electrical/1.0")
                                     ^^

Make sure both namespaces match exactly.

Regarding your comment asking about the use of version numbers in namespaces...

It is an unfortunately common but certainly not widely accepted practice to include a version number in an XML namespace. Realize that by doing so, you're effectively saying that every namespaced XML component (element or attribute) should now be considered to differ from its counterpart in the old namespace. This is rarely what you want.

How to select child node with XPath

1 Answers1

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