XPATH
What is XPath?
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XPath
XPath
XPath
XPath
XPath
is a syntax for defining parts of an XML document
uses path expressions to navigate in XML documents
contains a library of standard functions
is a major element in XSLT
is a W3C recommendation
is a non-XML syntax for addressing portions of an XML document. XPath has rapidly been
adopted by developers as a small query language.
With the increase in usage of xml being sent on internet for transferring data there was huge need
of some standard way for accessing data in a simple and fast manner.Thats what is Xpath is
about.
The XPath language is based on a tree representation of the XML document, and provides the
ability to navigate around the tree, selecting nodes by a variety of criteria. In popular use (though
not in the official specification), an XPath expression is often referred to simply as an XPath.
XPath is a language for finding information in an XML document. It allows consumers of Xml
to query it and access any part of it directly.It may return null, a string, a number or an xml node
itself. XPath is used to navigate through elements and attributes in an XML document.
Originally motivated by a desire to provide a common syntax and behavior model between
XPointer and XSLT, subsets of the XPath query language are used in other W3C specifications
such as XMLSchema and XForms.
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.
XPath Standard Functions
XPath includes over 100 built-in functions. There are functions for string values, numeric values,
date and time comparison, node and QName manipulation, sequence manipulation, Boolean
values, and more.
XPath is Used in XSLT
XPath is a major element in the XSLT standard. Without XPath knowledge you will not be able
to create XSLT documents.
You can read more about XSLT in our XSLT tutorial.
XQuery and XPointer are both built on XPath expressions. XQuery 1.0 and XPath 2.0 share the
same data model and support the same functions and operators.
You can read more about XQuery in our XQuery tutorial.
XPATH is a W3C Recommendation
XPath became a W3C Recommendation 16. November 1999.
XPath was designed to be used by XSLT, XPointer and other XML parsing software.
To read more about the XPATH activities at W3C, please read our W3C tutorial.
XPath Terminology
Nodes
In XPath, there are seven kinds of nodes: element, attribute, text, namespace, processinginstruction, comment, and document (root) nodes. XML documents are treated as trees of nodes.
The root of the tree is called the document node (or root node).
Look at the following XML document:
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
</bookstore>
Example of nodes in the XML document above:
<bookstore> (document node)
<author>J K. Rowling</author> (element node)
lang="en" (attribute node)
Atomic values
Atomic values are nodes with no children or parent.
Example of atomic values:
J K. Rowling
"en"
Items
Items are atomic values or nodes.
Relationship of Nodes
Parent
Each element and attribute has one parent.
In the following example; the book element is the parent of the title, author, year, and price:
<book>
<title>Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
Children
Element nodes may have zero, one or more children.
In the following example; the title, author, year, and price elements are all children of the book
element:
<book>
<title>Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
Siblings
Nodes that have the same parent.
In the following example; the title, author, year, and price elements are all siblings:
<book>
<title>Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
Ancestors
A node's parent, parent's parent, etc.
In the following example; the ancestors of the title element are the book element and the
bookstore element:
<bookstore>
<book>
<title>Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
</bookstore>
Descendants
A node's children, children's children, etc.
In the following example; descendants of the bookstore element are the book, title, author, year,
and price elements:
<bookstore>
<book>
<title>Harry Potter</title>
<author>J K. Rowling</author>
<year>2005</year>
<price>29.99</price>
</book>
</bookstore>
XPath uses path expressions to select nodes or node-sets in an XML document. The node is
selected by following a path or steps.
The XML Example Document
We will use the following XML document in the examples below.
<?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>
Selecting Nodes
XPath uses path expressions to select nodes in an XML document. The node is selected by
following a path or steps. The most useful path expressions are listed below:
Expression
Description
nodename
Selects all child nodes of the named node
/
Selects from the root node
//
Selects nodes in the document from the current node that match the selection no
matter where they are
.
Selects the current node
..
Selects the parent of the current node
@
Selects attributes
In the table below we have listed some path expressions and the result of the expressions:
Path Expression
Result
bookstore
Selects all the child nodes of the bookstore element
/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
//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 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.
In the table below we have listed some path expressions with predicates and the result of the
expressions:
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
Selecting Unknown Nodes
XPath wildcards can be used to select unknown XML elements.
Wildcard
Description
*
Matches any element node
@*
Matches any attribute node
node()
Matches any node of any kind
In the table below we have listed some path expressions and the result of the expressions:
Path Expression
Result
/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
Selecting Several Paths
By using the | operator in an XPath expression you can select several paths.
In the table below we have listed some path expressions and the result of the expressions:
Path Expression
Result
//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
The XML Example Document
We will use the following XML document in the examples below.
<?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>
Location Path Expression
A location path can be absolute or relative.
An absolute location path starts with a slash ( / ) and a relative location path does not. In both
cases the location path consists of one or more steps, each separated by a slash:
An absolute location path:
/step/step/...
A relative location path:
step/step/...
Each step is evaluated against the nodes in the current node-set.
A step consists of:
an axis (defines the tree-relationship between the selected nodes and the current node)
a node-test (identifies a node within an axis)
zero or more predicates (to further refine the selected node-set)
The syntax for a location step is:
axisname::nodetest[predicate]
Examples
Example
Result
child::book
Selects all book nodes that are children of the current node
attribute::lang
Selects the lang attribute of the current node
child::*
Selects all children of the current node
attribute::*
Selects all attributes of the current node
child::text()
Selects all text child nodes of the current node
child::node()
Selects all child nodes of the current node
descendant::book
Selects all book descendants of the current node
ancestor::book
Selects all book ancestors of the current node
ancestor-or-self::book
Selects all book ancestors of the current node - and the current as
well if it is a book node
child::*/child::price
Selects all price grandchildren of the current node
XPath Operators
Below is a list of the operators that can be used in XPath expressions:
Operator
Description
Example
Return value
|
Computes two node-sets
//book | //cd
Returns a node-set with
all book and cd elements
+
Addition
6+4
10
-
Subtraction
6-4
2
*
Multiplication
6*4
24
div
Division
8 div 4
2
=
Equal
price=9.80
true if price is 9.80
false if price is 9.90
!=
Not equal
price!=9.80
true if price is 9.90
false if price is 9.80
<
Less than
price<9.80
true if price is 9.00
false if price is 9.80
<=
Less than or equal to
price<=9.80
true if price is 9.00
false if price is 9.90
>
Greater than
price>9.80
true if price is 9.90
false if price is 9.80
>=
Greater than or equal to
price>=9.80
true if price is 9.90
false if price is 9.70
or
or
price=9.80 or price=9.70
true if price is 9.80
false if price is 9.50
and
and
price>9.00 and price<9.90
true if price is 9.80
false if price is 8.50
mod
Modulus (division remainder)
5 mod 2
1
Simple Example :
The basic XPath syntax is similar to filesystem addressing. If the path starts with the slash / ,
then it represents an absolute path to the required element.
/AAA
Select the root element AAA
<AAA>
<BBB/>
<CCC/>
<BBB/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC/>
</AAA>
/AAA/CCC
Select all elements CCC which are children of the root element AAA
<AAA>
<BBB/>
<CCC/>
<BBB/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC/>
</AAA>
/AAA/DDD/BBB
Select all elements BBB which are children of DDD which are children of the root
element AAA
<AAA>
<BBB/>
<CCC/>
<BBB/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC/>
</AAA>
If the path starts with // then all elements in the document which fulfill following criteria are
selected.
//BBB
Select all elements BBB
<AAA>
<BBB/>
<CCC/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
</CCC>
</AAA>
//DDD/BBB
Select all elements BBB which are children of DDD
<AAA>
<BBB/>
<CCC/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
</CCC>
</AAA>
The star * selects all elements located by preceeding path
/AAA/CCC/DDD/*
Select all elements enclosed by elements /AAA/CCC/DDD
<AAA>
<XXX>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</XXX>
<CCC>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</CCC>
<CCC>
<BBB>
<BBB>
<BBB/>
</BBB>
</BBB>
</CCC>
</AAA>
/*/*/*/BBB
Select all elements BBB which have 3 ancestors
<AAA>
<XXX>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</XXX>
<CCC>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</CCC>
<CCC>
<BBB>
<BBB>
<BBB/>
</BBB>
</BBB>
</CCC>
</AAA>
//*
Select all elements
<AAA>
<XXX>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</XXX>
<CCC>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</CCC>
<CCC>
<BBB>
<BBB>
<BBB/>
</BBB>
</BBB>
</CCC>
</AAA>
Expresion in square brackets can further specify an element. A number in the brackets gives the
position of the element in the selected set. The function last() selects the last element in the
selection.
/AAA/BBB[1]
Select the first BBB child of element AAA
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
</AAA>
/AAA/BBB[last()]
Select the last BBB child of element AAA
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
</AAA>
Attributes are specified by @ prefix.
//@id
Select all attributes @id
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[@id]
Select BBB elements which have attribute id
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[@name]
Select BBB elements which have attribute name
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[@*]
Select BBB elements which have any attribute
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[not(@*)]
Select BBB elements without an attribute
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
Values of attributes can be used as selection criteria. Function normalize-space removes leading
and trailing spaces and replaces sequences of whitespace characters by a single space.
//BBB[@id='b1']
Select BBB elements which have attribute id with value b1
<AAA>
<BBB id = "b1"/>
<BBB name = " bbb "/>
<BBB name = "bbb"/>
</AAA>
//BBB[@name='bbb']
Select BBB elements which have attribute name with value 'bbb'
<AAA>
<BBB id = "b1"/>
<BBB name = " bbb "/>
<BBB name = "bbb"/>
</AAA>
//BBB[normalize-space(@name)='bbb']
Select BBB elements which have attribute name with value bbb, leading and
trailing spaces are removed before comparison
<AAA>
<BBB id = "b1"/>
<BBB name = " bbb "/>
<BBB name = "bbb"/>
</AAA>
Function count() counts the number of selected elements
//*[count(BBB)=2]
Select elements which have two children BBB
<AAA>
<CCC>
<BBB/>
<BBB/>
<BBB/>
</CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
<EEE>
<CCC/>
<DDD/>
</EEE>
</AAA>
//*[count(*)=2]
Select elements which have 2 children
<AAA>
<CCC>
<BBB/>
<BBB/>
<BBB/>
</CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
<EEE>
<CCC/>
<DDD/>
</EEE>
</AAA>
//*[count(*)=3]
Select elements which have 3 children
<AAA>
<CCC>
<BBB/>
<BBB/>
<BBB/>
</CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
<EEE>
<CCC/>
<DDD/>
</EEE>
</AAA>
Function name() returns name of the element, the starts-with function returns true if the first
argument string starts with the second argument string, and the contains function returns true
if the first argument string contains the second argument string.
//*[name()='BBB']
Select all elements with name BBB, equivalent with //BBB
<AAA>
<BCC>
<BBB/>
<BBB/>
<BBB/>
</BCC>
<DDB>
<BBB/>
<BBB/>
</DDB>
<BEC>
<CCC/>
<DBD/>
</BEC>
</AAA>
//*[starts-with(name(),'B')]
Select all elements name of which starts with letter B
<AAA>
<BCC>
<BBB/>
<BBB/>
<BBB/>
</BCC>
<DDB>
<BBB/>
<BBB/>
</DDB>
<BEC>
<CCC/>
<DBD/>
</BEC>
</AAA>
//*[contains(name(),'C')]
Select all elements name of which contain letter C
<AAA>
<BCC>
<BBB/>
<BBB/>
<BBB/>
</BCC>
<DDB>
<BBB/>
<BBB/>
</DDB>
<BEC>
<CCC/>
<DBD/>
</BEC>
</AAA>
The string-length function returns the number of characters in the string. You must use &lt; as
a substitute for < and &gt; as a substitute for > .
//*[string-length(name()) = 3]
Select elements with three-letter name
<AAA>
<Q/>
<SSSS/>
<BB/>
<CCC/>
<DDDDDDDD/>
<EEEE/>
</AAA>
Several paths can be combined with | separator.
//CCC | //BBB
Select all elements CCC and BBB
<AAA>
<BBB/>
<CCC/>
<DDD>
<CCC/>
</DDD>
<EEE/>
</AAA>
/AAA/EEE | //BBB
Select all elements BBB and elements EEE which are children of root element
AAA
<AAA>
<BBB/>
<CCC/>
<DDD>
<CCC/>
</DDD>
<EEE/>
</AAA>
/AAA/EEE | //DDD/CCC | /AAA | //BBB
Number of combinations is not restricted
<AAA>
<BBB/>
<CCC/>
<DDD>
<CCC/>
</DDD>
<EEE/>
</AAA>
The child axis contains the children of the context node. The child axis is the default axis and it
can be omitted.
/AAA
Equivalent of /child::AAA
<AAA>
<BBB/>
<CCC/>
</AAA>
/child::AAA
Equivalent of /AAA
<AAA>
<BBB/>
<CCC/>
</AAA>
/AAA/BBB
Equivalent of /child::AAA/child::BBB
<AAA>
<BBB/>
<CCC/>
</AAA>
/child::AAA/child::BBB
Equivalent of /AAA/BBB
<AAA>
<BBB/>
<CCC/>
</AAA>
/child::AAA/BBB
Both possibilities can be combined
<AAA>
<BBB/>
<CCC/>
</AAA>
The descendant axis contains the descendants of the context node; a descendant is a child or a
child of a child and so on; thus the descendant axis never contains attribute or namespace
nodes
/descendant::*
Select all descendants of document root and therefore all elements
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
/AAA/BBB/descendant::*
Select all descendants of /AAA/BBB
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
//CCC/descendant::*
Select all elements which have CCC among its ancestors
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
//CCC/descendant::DDD
Select elements DDD which have CCC among its ancestors
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
The parent axis contains the parent of the context node, if there is one.
//DDD/parent::*
Select all parents of DDD element
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
The ancestor axis contains the ancestors of the context node; the ancestors of the context node
consist of the parent of context node and the parent's parent and so on; thus, the ancestor axis
will always include the root node, unless the context node is the root node.
/AAA/BBB/DDD/CCC/EEE/ancestor::*
Select all elements given in this absolute path
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
//FFF/ancestor::*
Select ancestors of FFF element
<AAA>
<BBB>
<DDD>
<CCC>
<DDD/>
<EEE/>
</CCC>
</DDD>
</BBB>
<CCC>
<DDD>
<EEE>
<DDD>
<FFF/>
</DDD>
</EEE>
</DDD>
</CCC>
</AAA>
The following-sibling axis contains all the following siblings of the context node.
/AAA/BBB/following-sibling::*
<AAA>
<BBB>
<CCC/>
<DDD/>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//CCC/following-sibling::*
<AAA>
<BBB>
<CCC/>
<DDD/>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The preceding-sibling axis contains all the preceding siblings of the context node
/AAA/XXX/preceding-sibling::*
<AAA>
<BBB>
<CCC/>
<DDD/>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//CCC/preceding-sibling::*
<AAA>
<BBB>
<CCC/>
<DDD/>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The following axis contains all nodes in the same document as the context node that are after
the context node in document order, excluding any descendants and excluding attribute nodes
and namespace nodes.
/AAA/XXX/following::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
<DDD>
<EEE/>
</DDD>
</ZZZ>
<FFF>
<GGG/>
</FFF>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//ZZZ/following::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
<DDD>
<EEE/>
</DDD>
</ZZZ>
<FFF>
<GGG/>
</FFF>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The preceding axis contains all nodes in the same document as the context node that are
before the context node in document order, excluding any ancestors and excluding attribute
nodes and namespace nodes
/AAA/XXX/preceding::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
</ZZZ>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/preceding::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
</ZZZ>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The descendant-or-self axis contains the context node and the descendants of the context node
/AAA/XXX/descendant-or-self::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
</ZZZ>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//CCC/descendant-or-self::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
</ZZZ>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The ancestor-or-self axis contains the context node and the ancestors of the context node;
thus, the ancestor-or-self axis will always include the root node.
/AAA/XXX/DDD/EEE/ancestor-or-self::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
</ZZZ>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/ancestor-or-self::*
<AAA>
<BBB>
<CCC/>
<ZZZ>
<DDD/>
</ZZZ>
</BBB>
<XXX>
<DDD>
<EEE/>
<DDD/>
<CCC/>
<FFF/>
<FFF>
<GGG/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The ancestor, descendant, following, preceding and self axes partition a document (ignoring
attribute and namespace nodes): they do not overlap and together they contain all the nodes in
the document.
//GGG/ancestor::*
<AAA>
<BBB>
<CCC/>
<ZZZ/>
</BBB>
<XXX>
<DDD>
<EEE/>
<FFF>
<HHH/>
<GGG>
<JJJ>
<QQQ/>
</JJJ>
<JJJ/>
</GGG>
<HHH/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/descendant::*
<AAA>
<BBB>
<CCC/>
<ZZZ/>
</BBB>
<XXX>
<DDD>
<EEE/>
<FFF>
<HHH/>
<GGG>
<JJJ>
<QQQ/>
</JJJ>
<JJJ/>
</GGG>
<HHH/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/following::*
<AAA>
<BBB>
<CCC/>
<ZZZ/>
</BBB>
<XXX>
<DDD>
<EEE/>
<FFF>
<HHH/>
<GGG>
<JJJ>
<QQQ/>
</JJJ>
<JJJ/>
</GGG>
<HHH/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/preceding::*
<AAA>
<BBB>
<CCC/>
<ZZZ/>
</BBB>
<XXX>
<DDD>
<EEE/>
<FFF>
<HHH/>
<GGG>
<JJJ>
<QQQ/>
</JJJ>
<JJJ/>
</GGG>
<HHH/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/self::*
<AAA>
<BBB>
<CCC/>
<ZZZ/>
</BBB>
<XXX>
<DDD>
<EEE/>
<FFF>
<HHH/>
<GGG>
<JJJ>
<QQQ/>
</JJJ>
<JJJ/>
</GGG>
<HHH/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
//GGG/ancestor::* | //GGG/descendant::* | //GGG/following::* |
//GGG/preceding::* | //GGG/self::*
<AAA>
<BBB>
<CCC/>
<ZZZ/>
</BBB>
<XXX>
<DDD>
<EEE/>
<FFF>
<HHH/>
<GGG>
<JJJ>
<QQQ/>
</JJJ>
<JJJ/>
</GGG>
<HHH/>
</FFF>
</DDD>
</XXX>
<CCC>
<DDD/>
</CCC>
</AAA>
The div operator performs floating-point division, the mod operator returns the remainder from
a truncating division. The floor function returns the largest (closest to positive infinity) number
that is not greater than the argument and that is an integer.The ceiling function returns the
smallest (closest to negative infinity) number that is not less than the argument and that is an
integer.
//BBB[position() mod 2 = 0 ]
Select even BBB elements
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<CCC/>
<CCC/>
<CCC/>
</AAA>
//BBB[ position() = floor(last() div 2 + 0.5) or position() =
ceiling(last() div 2 + 0.5) ]
Select middle BBB element(s)
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<CCC/>
<CCC/>
<CCC/>
</AAA>
//CCC[ position() = floor(last() div 2 + 0.5) or position() =
ceiling(last() div 2 + 0.5) ]
Select middle CCC element(s)
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
<CCC/>
<CCC/>
<CCC/>
</AAA>
The basic XPath syntax is similar to filesystem addressing. If the path starts with the slash / ,
then it represents an absolute path to the required element.
/AAA
Select the root element AAA
<AAA>
<BBB/>
<CCC/>
<BBB/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC/>
</AAA>
/AAA/CCC
Select all elements CCC which are children of the root element AAA
<AAA>
<BBB/>
<CCC/>
<BBB/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC/>
</AAA>
/AAA/DDD/BBB
Select all elements BBB which are children of DDD which are children of the root
element AAA
<AAA>
<BBB/>
<CCC/>
<BBB/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC/>
</AAA>
If the path starts with // then all elements in the document which fulfill following criteria are
selected.
//BBB
Select all elements BBB
<AAA>
<BBB/>
<CCC/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
</CCC>
</AAA>
//DDD/BBB
Select all elements BBB which are children of DDD
<AAA>
<BBB/>
<CCC/>
<BBB/>
<DDD>
<BBB/>
</DDD>
<CCC>
<DDD>
<BBB/>
<BBB/>
</DDD>
</CCC>
</AAA>
The star * selects all elements located by preceeding path
/AAA/CCC/DDD/*
Select all elements enclosed by elements /AAA/CCC/DDD
<AAA>
<XXX>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</XXX>
<CCC>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</CCC>
<CCC>
<BBB>
<BBB>
<BBB/>
</BBB>
</BBB>
</CCC>
</AAA>
/*/*/*/BBB
Select all elements BBB which have 3 ancestors
<AAA>
<XXX>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</XXX>
<CCC>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</CCC>
<CCC>
<BBB>
<BBB>
<BBB/>
</BBB>
</BBB>
</CCC>
</AAA>
//*
Select all elements
<AAA>
<XXX>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</XXX>
<CCC>
<DDD>
<BBB/>
<BBB/>
<EEE/>
<FFF/>
</DDD>
</CCC>
<CCC>
<BBB>
<BBB>
<BBB/>
</BBB>
</BBB>
</CCC>
</AAA>
Expresion in square brackets can further specify an element. A number in the brackets gives the
position of the element in the selected set. The function last() selects the last element in the
selection.
/AAA/BBB[1]
Select the first BBB child of element AAA
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
</AAA>
/AAA/BBB[last()]
Select the last BBB child of element AAA
<AAA>
<BBB/>
<BBB/>
<BBB/>
<BBB/>
</AAA>
Attributes are specified by @ prefix.
//@id
Select all attributes @id
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[@id]
Select BBB elements which have attribute id
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[@name]
Select BBB elements which have attribute name
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[@*]
Select BBB elements which have any attribute
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
//BBB[not(@*)]
Select BBB elements without an attribute
<AAA>
<BBB id = "b1"/>
<BBB id = "b2"/>
<BBB name = "bbb"/>
<BBB/>
</AAA>
Values of attributes can be used as selection criteria. Function normalize-space removes leading
and trailing spaces and replaces sequences of whitespace characters by a single space.
//BBB[@id='b1']
Select BBB elements which have attribute id with value b1
<AAA>
<BBB id = "b1"/>
<BBB name = " bbb "/>
<BBB name = "bbb"/>
</AAA>
//BBB[@name='bbb']
Select BBB elements which have attribute name with value 'bbb'
<AAA>
<BBB id = "b1"/>
<BBB name = " bbb "/>
<BBB name = "bbb"/>
</AAA>
//BBB[normalize-space(@name)='bbb']
Select BBB elements which have attribute name with value bbb, leading and
trailing spaces are removed before comparison
<AAA>
<BBB id = "b1"/>
<BBB name = " bbb "/>
<BBB name = "bbb"/>
</AAA>
Example of Unions ( | )
This example demonstrates unions. The following XPath expression finds the green and blue
nodes in the XML file:
x | y/x
XML File (data1.xml)
<?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 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:for-each>
</xsl:template>
</xsl:stylesheet>
Formatted Output
greenbluebluegreen