XML element has namespace, my XPATH does not work

Question

I was given the following XML:

Answer 1

In XPath, you have to assign a prefix to the namespace. How you do that depends on the XPath software/library you are using, but assuming you associate the namespace URI http://some_url with the namespace prefix someUrl, you can change your XPath expression as follows:

/root/items/item/details/someUrl:data

Answer 2

This is one of the most FAQ in XPath / XSLT:

XPath interprets an unprefixed element name as belonging to "no namespace" and this is the reason elements with unprefixed names belonging to a default (nonempty) namespace aren't selected when only their unprefixed name is specified as a node-test in an XPath expression.

The solution is either:

1. Create a namespace binding where a prefix (say "x") is associated with the default namespace, then specify x:elementName instead of elementName.

2. Use long, ugly and unreliable expressions like: *[name() = 'elementName']

Here is an XSLT transformation using the above method1. :

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:a="http://some_url">
 <xsl:output method="text"/>

 <xsl:template match="/">
  <xsl:value-of select=
  "/root/items/item/details/a:data/a:weight"/>
 </xsl:template>
</xsl:stylesheet>

When this transformation is applied (using Saxon 6.5.4 or any other compliant XSLT 1.0 processor) on the provided XML document:

<root>
    <items>
        <item>
            <title>Item</title>
            <details>
                <data xmlns="http://some_url">
                    <length>10</length>
                    <weight>1.2</weight>
                </data>
            </details>
        </item>
    </items>
</root>

The correct/wanted node is selected and its string value is copied to the output:

1.2