What is XPath?

XPath Path Expressions

XPath uses path expressions to select nodes or node-sets in an XML document. These path expressions look very much like the expressions you see when you work with a traditional computer file system.

<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
<title lang="eng">About CSS</title>
<price>16</price>
</book>
<book>
<title lang="eng">Learning XML</title>
<price>39</price>
</book>
<book>
<title lang="cze">Learning SVG</title>
<price>23</price>
</book>
</bookstore>


Expression Description
/ Selects from the root node
// Selects nodes in the document from the current node that matches the selection no matter where they are
. Selects the current node
.. Selects the parent of the current node
@ Selects attributes
* Matches any element node
@* Matches any attribute node
node() Matches any node of any kind


Examples Description
/bookstore Selects the root element bookstore
//book Selects all book elements no matter where they are in the document
/bookstore//book Selects all book elements that are descendant of the bookstore element, no matter where they are under the bookstore element
//@lang Selects all attributes that is named lang
/bookstore/book[1] Selects the first book element that is the child of the bookstore element
/bookstore/book[last()] Selects the last book element that is the child of the bookstore element
/bookstore/book[last()-1] Selects the last but one book element that is the child of the bookstore element
//title[@lang] Selects all the title elements that have an attribute named lang
//title[@lang='eng'] Selects all the title elements that have an attribute named lang with a value of 'eng'
/bookstore/book[price>20] Selects all the book elements of the bookstore element that have a price element with a value greater than 20
/bookstore/book[price>20]/title Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 20
/bookstore/* Selects all the child nodes of the bookstore element
//* Selects all elements in the document
//title[@*] Selects all title elements which have any attribute
//book/title | //book/price Selects all the title AND price elements of all book elements
//title | //price Selects all the title AND price elements in the document
/bookstore/book/title | //price Selects all the title elements of the book element of the bookstore element AND all the price elements in the document


Custom Functions

XPath Type Functions
Node set last(), position(), count(), id(), local-name(), namespace-uri(), name()
String string(), concat(), starts-with(), contains(), substring-before(), substring-after(), substring(), string-length(), normalize-space(), translate()
Boolean boolean(), not(), true(), false(), lang()
Number number(), sum(), floor(), ceiling(), round()
XSLT 1.0 additions document(), key(), format-number(), current(), unparsed-entity-uri(), generate-id(), system-property()

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