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XPATH

XPATH TERMINOLOGY

SEVEN KIND OF NODES:

  • element
  • attribute
  • text
  • namespace
  • processing-instruction
  • comment
  • document nodes

ATOMIC VALUES

nodes with no children or parent

Items are atomic values or nodes

RELATIONSHIP OF NODES

  • parent
  • children
  • siblings
  • ancestors
  • descendants

XPATH SYNATX

SELECTING NODES

EXPRESSION DESCRIPTION
nodename selects all nodes withs the name "nodename"
/ selects from the root node
// selects nodes in the document from the current node that match the selection no matter where they are
. select the current node
.. selects the parent of th document
@ selects all attributes

PREDICATES

EXPRESSION DESCRIPTION
/bookstore/book[1] selects the first book element that is the child of bookstore element
/bookstore/book[last()] selects the last book element that is the child of bookstore element
/bookstore/book[last()-1] selects the last second book element that is the child of bookstore element
/bookstore/book[postition()<3] selects the first two book element that is the child of bookstore element
//title[@lang] selects all the title that has a "lang" attribute
/bookstore/book[price>35.00] selects all the book element that price is less than 35.00
/bookstore/book[price>35.00]/title slects all the title element of book element that the priceis more than 35.00

SELECT UNKNOWN NODES

WILDCARD DESCRIPTION
* matches any element nodes
@* matches any attribute node
node() match any node of any kind

SELECT SEVERAL PATHS

PATH EXPRESSION RESULTS
//book/title &#124; //book/price selects all the title AND price elements of all book elements
//title &#124; //price selects all the title AND price elements in the documnet
/bookstore/book/title &#124; //price selects all the title elements of the book element of bookstore element AND all the price elements in the documnets

xpath axes

axis defines a node-set relative to the current node

axisname result
ancestor selects all the ancestors(parent, grandparent) of the current node
ancestor-or-self selects all the ancestors(parent, grandparent) of the current node and the current node
attribute selects all the attribute 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 it self
following selects everythong in the document after the closing tag of the current node
following-sibling selects all siblings after the current node
namespace selects all namespace of the current node
parent selects the parent of the current node
preceding selects all nodes thata 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

  • absolute location: /step/step
  • relative location: step/step/

a step consist of - an axis(defines the tree-relativeship between the selected node and the current node.) - a node-test(idetified a node within an axis) - zero or more predicates(to further refine the selected node-set)

syntax for a location step

axisname::nodetest[predicate]

examples

example result
child::book selects all book nodes that are child of the current node
attribute::lang selects the lang attribut of the current node
child::* selects all elements of children of th current node
attribute::* selects all the attribute 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
ancenstor::book selects all ancestors of the current node
ancestor-or-self::book selects all ancestors of the current node and itself if it is a book node
child::*/child::price selects all price grandchildren of the current node

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