XPath axes

Build 1501 on 14/Nov/2017  This topic last edited on: 21/Feb/2014, at 09:13

An axis defines a node-set relative to the current node.

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>

XPath Axes

AxisName

Result

ancestor

Selects all ancestors (parent, grandparent, etc.) of the current node

ancestor-or-self

Selects all ancestors (parent, grandparent, etc.) of the current node and the current node itself

attribute

Selects all attributes of the current node

child

Selects all children of the current node

descendant

Selects all descendants (children, grandchildren, etc.) of the current node

descendant-or-self

Selects all descendants (children, grandchildren, etc.) of the current node and the current node itself

following

Selects everything in the document after the closing tag of the current node

following-sibling

Selects all siblings after the current node

namespace

Selects all namespace nodes of the current node

parent

Selects the parent of the current node

preceding

Selects all nodes that appear before the current node in the document, except ancestors, attribute nodes and namespace nodes

preceding-sibling

Selects all siblings before the current node

self

Selects the current node

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 element children of the current node

attribute::*

Selects all attributes of the current node

child::text()

Selects all text node children of the current node

child::node()

Selects all children 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