The document is a practical guide on XPath by Arne Blankerts and Tobias Schlitt, outlining its application in selecting XML data and navigating XML trees. It includes essential concepts, syntax, functions, and integration with PHP, along with a quiz to test understanding. The guide aims to provide a comprehensive understanding of XPath for programming and document manipulation.

1. XPath - A practical guide
Arne Blankerts <arne@thephp.cc>, TobiasSchlitt <toby@php.net>
IPC 2009
2009-11-17
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 1 / 26

2. Outline
1 Welcome
2 Introduction
3 In details
4 Quiz
5 The end
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 2 / 26

3. Arne Blankerts
Arne Blankerts <arne@thephp.cc>
PHP since 1999 (10 years of PHP!)
Co-Founder of thePHP.cc
ballyhoo. werbeagentur.
Open source addicted
Inventor and lead developer of fCMS site
system
Contributor and translator for the PHP manual
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 3 / 26

4. Tobias Schlitt
Tobias Schlitt <toby@php.net>
PHP since 2001
Freelancing consultant
Qualified IT Specialist
Studying CS at TU Dortmund
(finishing 2010)
OSS addicted
PHP
eZ Components
PHPUnit
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 4 / 26

5. Outline
1 Welcome
2 Introduction
Overview
Basics
3 In details
4 Quiz
5 The end
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 5 / 26

6. Overview
XPath
Enables you to select information parts from XML documents.
Traverse the XML tree
Select XML nodes
W3C recommendation
Version 1: November 1999
Version 2: January 2007
Fields of application
XSLT (XML Stylesheet Language Transformations)
Fetching XML nodes within programming languages
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 6 / 26

7. Addressing
Every XPath expression matches a set of nodes (0..n)
It encodes an “address” for the selected nodes
Simple XPath expressions look similar to Unix file system addresses
Absolute vs. relative addressing
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 7 / 26

8. Practical
Let’s dig into the code
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 8 / 26

9. Outline
1 Welcome
2 Introduction
3 In details
Syntax
Specialities
Functions
Axis
PHP function integration
4 Quiz
5 The end
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 9 / 26

10. Syntax elements
/ Level seperator
// Multi-level seperator
* Wildcard
@ Attribute prefix
@* Attribute wildcard
[...] Filter / condition
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 10 / 26

11. Contexts
Every expression step creates new context
Next evaluated in context created by previous step
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 11 / 26

12. Navigation
/ One level down
// Any number of levels down
../ One level up
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 12 / 26

13. Practical
Let’s dig into the code
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 13 / 26

14. Indexing
Access nodes by position: [2]
Start index
Indexing generally 1 based
Some Internet Explorer versions start with 0
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 14 / 26

15. Union
Union the node sets selected by multiple XPath expressions.
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 15 / 26

16. Practical
Let’s dig into the code
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 16 / 26

17. Functions
String Context
string-join() position()
substring() last()
starts-with() Aggregate
contains() count()
string-length() min() / max()
Math Node
round() local-name()
floor() Logic
not()
true()
Function overview
An overview on all functions can be found on
http://www.w3.org/TR/xpath-functions/
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 17 / 26

18. Axis
13 dimensions
Imagine an XML document to be a 13 dimensional space...
Axis Shortcut
ancestor
ancestor-or-self
attribute @
child -
descendant
descendant-or-self //
following
following-sibling
namespace
parent ..
preceding
preceding-sibling
self .
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 18 / 26

19. Practical
Let’s dig into the code
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 19 / 26

20. PHP function integration
Register PHP callbacks to enhance functionality
Possible since PHP 5.3.0
Works with functions and static methods
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 20 / 26

21. Practical
Let’s dig into the code
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 21 / 26

22. Outline
1 Welcome
2 Introduction
3 In details
4 Quiz
5 The end
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 22 / 26

23. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

24. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

25. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

26. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

27. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

28. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

29. Quiz
//node
/root/element
/root/element[1]
@id
/root//node/@name
/root/element[@name = ’php’]/@*.
./some/*[@class=’tek’]/@id
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 23 / 26

30. Outline
1 Welcome
2 Introduction
3 In details
4 Quiz
5 The end
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 24 / 26

31. Q/A
Are there any questions left?
Please give us some feedback!
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 25 / 26

32. The end
Thanks for being here!
We hope you enjoyed the session!
Slides and material
Delivered by Software & Support
http://schlitt.info/opensource
On slideshare: http://www.slideshare.net/tobyS
Contact us:
Arne Blankerts <arne@thephp.cc>
Tobias Schlitt <toby@php.net>
Please rate our talk at: http://joind.in/1042
Arne Blankerts, Tobias Schlitt (IPC 2009) XPath - A practical guide 2009-11-17 26 / 26