Namespace Issue - All XPath queries returning null

Question

I have an XML document $books that uses namespaces, and I've tried to create an XML namespacemanager by using something like $ns = New-Object System.Xml.XmlNamespaceManager($books.NameTable). I'm not quite sure what I'm doing wrong after that though. I'm trying to use SelectSingleNode() to search the XML document for specific nodes I need, but all my XPath queries return null.

Here's a bit of the xml document:

<ernm:NewReleaseMessage xmlns:ernm="http://ddex.net/xml/ern/341" xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" LanguageAndScriptCode="en" MessageSchemaVersionId="/ern/341" xs:schemaLocation="http://ddex.net/xml/ern/341 http://ddex.net/xml/ern/341/release-notification.xsd">
    <MessageHeader>
        <MessageId>123123</MessageId>
        <MessageRecipient>
            <PartyId>567567</PartyId>
                <PartyName>
                    <FullName>John Smith</FullName>
                </PartyName>
        </MessageRecipient>
    </MessageHeader>
</ernm:NewReleaseMessage>

Also, here's a bit of what I've tried so far in order to get SelectSingleNode() working correctly:

[xml]$books = Get-Content xmlpath.xml
$ns = New-Object System.Xml.XmlNamespaceManager($books.NameTable)
$ns.AddNamespace("ns", $books.DocumentElement.NamespaceURI)

$books.SelectSingleNode("//newreleasemessage", $ns) #returns null
$books.SelectSingleNode("//ns:newreleasemessage", $ns) #returns null
$books.SelectSingleNode("//ernm:newreleasemessage", $ns) #returns null
$books.SelectSingleNode("//xmlns:newreleasemessage", $ns) #returns null
$books.SelectSingleNode("//xml:newreleasemessage", $ns) #returns null

I've also tried other nodes than newreleasemessage and it still comes back blank, I just wanted to provide some examples of what I've tried. What's the correct way of using namespaces here?

Ansgar Wiechers · Accepted Answer · 2016-10-04 20:15:16Z

2

XPath queries are case-sensitive. This works:

$books.SelectSingleNode("//ns:NewReleaseMessage", $ns)

answered Oct 4, 2016 at 20:15

Ansgar Wiechers

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2 Comments

Matthew Goode Over a year ago

Sweet lord I feel stupid. Thank you, have your upvote. Why isn't that plastered at the top of every single xpath introduction!?

Michael Kay Over a year ago

Because it's only a problem for people who have spent the last few years writing in languages that are not case-sensitive, and they are in a minority.

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