Xpath Example

This topic reviews the syntax examples that appear throughout the XPath Reference. All are based on the Sample XML File for XPath Syntax (inventory.xml). For an example of using an XPath expression in a test file, see "Example of Unions ( | )", at the bottom of this topic.

Expression	Refers to
Xml  Copy Code ./author	All <author> elements within the current context. Note that this is equivalent to the expression in the next row.
Xml  Copy Code author	All <author> elements within the current context.
Xml  Copy Code first.name	All <first.name> elements within the current context.
Xml  Copy Code /bookstore	The document element (<bookstore>) of this document.
Xml  Copy Code //author	All <author> elements in the document.
Xml  Copy Code book[/bookstore/@specialty = @style]	All <book> elements whose style attribute value is equal to the specialty attribute value of the <bookstore> element at the root of the document.
Xml  Copy Code author/first-name	All <first-name> elements that are children of an <author> element.
Xml  Copy Code bookstore//title	All <title> elements one or more levels deep in the <bookstore> element (arbitrary descendants). Note that this is different from the expression in the next row.
Xml  Copy Code bookstore/*/title	All <title> elements that are grandchildren of <bookstore> elements.
Xml  Copy Code bookstore//book/excerpt//emph	All <emph> elements anywhere inside <excerpt> children of <book> elements, anywhere inside the <bookstore> element.
Xml  Copy Code .//title	All <title> elements one or more levels deep in the current context. Note that this situation is essentially the only one in which the period notation is required.
Xml  Copy Code author/*	All elements that are the children of <author> elements.
Xml  Copy Code book/*/last-name	All <last-name> elements that are grandchildren of <book> elements.
Xml  Copy Code */*	All grandchildren elements of the current context.
Xml  Copy Code *[@specialty]	All elements with the specialty attribute.
Xml  Copy Code @style	The style attribute of the current context.
Xml  Copy Code price/@exchange	The exchange attribute on <price> elements within the current context.
Xml  Copy Code price/@exchange/total	Returns an empty node set, because attributes do not contain element children. This expression is allowed by the XML Path Language (XPath) grammar, but is not strictly valid.
Xml  Copy Code book[@style]	All <book> elements with style attributes, of the current context.
Xml  Copy Code book/@style	The style attribute for all <book> elements of the current context.
Xml  Copy Code @*	All attributes of the current element context.
Xml  Copy Code ./first-name	All <first-name> elements in the current context node. Note that this is equivalent to the expression in the next row.
Xml  Copy Code first-name	All <first-name> elements in the current context node.
Xml  Copy Code author[1]	The first <author> element in the current context node.
Xml  Copy Code author[first-name][3]	The third <author> element that has a <first-name> child.
Xml  Copy Code my:book	The <book> element from the my namespace.
Xml  Copy Code my:*	All elements from the my namespace.
Xml  Copy Code @my:*	All attributes from the my namespace (this does not include unqualified attributes on elements from the my namespace).

Note that indexes are relative to the parent. Consider the following data:

Xml	Copy Code
<x> <y/> <y/></x><x> <y/> <y/></x>

Expression	Refers to
Xml  Copy Code x/y[1]	The first <y> child of each <x>. This is equivalent to the expression in the next row.
Xml  Copy Code x/y[position() = 1]	The first <y> child of each <x>.
Xml  Copy Code (x/y)[1]	The first <y> from the entire set of <y> children of <x> elements.
Xml  Copy Code x[1]/y[2]	The second <y> child of the first <x>.

The remaining examples refer to the Sample XML file for XPath.

Expression	Refers to
book[last()]	The last <book> element of the current context node.
Xml  Copy Code book/author[last()]	The last <author> child of each <book> element of the current context node.
Xml  Copy Code (book/author)[last()]	The last <author> element from the entire set of <author> children of <book> elements of the current context node.
Xml  Copy Code book[excerpt]	All <book> elements that contain at least one <excerpt> element child.
Xml  Copy Code book[excerpt]/title	All <title> elements that are children of <book> elements that also contain at least one <excerpt> element child.
Xml  Copy Code book[excerpt]/author[degree]	All <author> elements that contain at least one <degree> element child, and that are children of <book> elements that also contain at least one <excerpt> element.
Xml  Copy Code book[author/degree]	All <book> elements that contain <author> children that in turn contain at least one <degree> child.
Xml  Copy Code author[degree][award]	All <author> elements that contain at least one <degree> element child and at least one <award> element child.
Xml  Copy Code author[degree and award]	All <author> elements that contain at least one <degree> element child and at least one <award> element child.
Xml  Copy Code author[(degree or award) and publication]	All <author> elements that contain at least one <degree> or <award> and at least one <publication> as the children
Xml  Copy Code author[degree and not(publication)]	All <author> elements that contain at least one <degree> element child and that contain no <publication> element children.
Xml  Copy Code author[not(degree or award) and publication]	All <author> elements that contain at least one <publication> element child and contain neither <degree> nor <award> element children.
author[last-name = "Bob"]	All <author> elements that contain at least one <last-name> element child with the value Bob.
Xml  Copy Code author[last-name[1] = "Bob"]	All <author> elements where the first <last-name> child element has the value Bob. Note that this is equivalent to the expression in the next row.
Xml  Copy Code author[last-name [position()=1]= "Bob"]	All <author> elements where the first <last-name> child element has the value Bob.
Xml  Copy Code degree[@from != "Harvard"]	All <degree> elements where the from attribute is not equal to "Harvard".
Xml  Copy Code author[. = "Matthew Bob"]	All <author> elements whose value is Matthew Bob.
Xml  Copy Code author[last-name = "Bob" and ../price &gt; 50]	All <author> elements that contain a <last-name> child element whose value is Bob, and a <price> sibling element whose value is greater than 50.
Xml  Copy Code book[position() &lt;= 3]	The first three books (1, 2, 3).
Xml  Copy Code author[not(last-name = "Bob")]	All <author> elements that do no contain <last-name> child elements with the value Bob.
Xml  Copy Code author[first-name = "Bob"]	All <author> elements that have at least one <first-name> child with the value Bob.
Xml  Copy Code author[* = "Bob"]	all author elements containing any child element whose value is Bob.
Xml  Copy Code author[last-name = "Bob" and first-name = "Joe"]	All <author> elements that has a <last-name> child element with the value Bob and a <first-name> child element with the value Joe.
Xml  Copy Code price[@intl = "Canada"]	All <price> elements in the context node which have an intl attribute equal to "Canada".
Xml  Copy Code degree[position() &lt; 3]	The first two <degree> elements that are children of the context node.
Xml  Copy Code p/text()[2]	The second text node in each <p> element in the context node.
Xml  Copy Code ancestor::book[1]	The nearest <book> ancestor of the context node.
Xml  Copy Code ancestor::book[author][1]	The nearest <book> ancestor of the context node and this <book> element has an <author> element as its child.
Xml  Copy Code ancestor::author[parent::book][1]	The nearest <author> ancestor in the current context and this <author> element is a child of a <book> element.

Example of Unions ( | )

To demonstrate the union operation, we use the following XPath expression:

x | y/x

selects all the <x> elements whose values are green or blue in the following XML file:

XML File (data1.xml)

Xml	Copy Code
<?xml version='1.0'?><?xml-stylesheet type="text/xsl" href="union.xsl"?><root> <x>green</x> <y> <x>blue</x> <x>blue</x> </y> <z> <x>red</x> <x>red</x> </z> <x>green</x></root>

XSLT File (union.xsl)

Xml	Copy Code
<?xml version='1.0'?><xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="root"> <xsl:for-each select="x | y/x"> <xsl:value-of select="."/>, <xsl:if test="not(position()=last())">,</xsl:if> </xsl:for-each></xsl:template> </xsl:stylesheet>

Formatted Output

green,blue,blue,green

Processor Output

<?xml version="1.0" encoding="UTF-16"?>green,blue,blue,green