xpath

XML example document

<?xml version="1.0" encoding="ISO-8859-1"?>

<bookstore>

<book>

<title lang="eng">Harry Potter</title>

<price>29.99</price>

</book>

<book>

<title lang="eng">Learning XML</title>

<price>39.95</price>

</book>

</bookstore>

Expression	Description	Example
nodename	Selects all child nodes of the named node	bookstore -- Selects all the child nodes of the bookstore element
/	Selects from the root node	/bookstore -- Selects the root element bookstore.Note: If the path starts with a slash ( / ) it always represents an absolute path to an element! bookstore/book -- Selects all book elements that are children of bookstore
//	Selects nodes in the document from the current node that match the selection no matter where they are	//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
.	Selects the current node
..	Selects the parent of the current node
@	Selects attributes	//@lang -- Selects all attributes that are named lang.

Predicates
Predicates are used to find a specific node or a node that contains a specific value. Predicates are always embedded in square brackets.

Path Expression	Result
/bookstore/book[1]	Selects the first book element that is the child of the bookstore element. Note: IE5 and later has implemented that [0] should be the first node, but according to the W3C standard it should have been [1]!!
/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
/bookstore/book[position()<3]	Selects the first two book elements that are children 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>35.00]	Selects all the book elements of the bookstore element that have a price element with a value greater than 35.00
/bookstore/book[price>35.00]/title	Selects all the title elements of the book elements of the bookstore element that have a price element with a value greater than 35.00

Wildcard	Description
*	Matches any element node	/bookstore/* --Selects all the child nodes of the bookstore element //* --Selects all elements in the document
@*	Matches any attribute node	//title[@*] --Selects all title elements which have any attribute
node()	Matches any node of any kind

| for several Paths
//book/title | //book/price
--Selects all the title AND price elements of all book elements.

XPath Operators
Operators can be used in XPath expressions. It supports +,-,*,div, =,!=,...,mod. The special one is "div", because "/" is used for paths.

/bookstore/book[1]/price returns the price node of book1
/bookstore/book[1]/price/text() returns the text of the price of book1, which is 29.99