introductionto xslt

Introduction to XSLT

2

Introduction to XSLTAgenda

The X* Ecosystem (XSL, XPath, XQuery...)

XML Refresh/Terminology

XPath: Addresses for XML documents

XSLT Basics: template and value-of

XSLT Loops: apply-templates and for-each

XSLT Decisions: if and choose

XSLT Variables: variable and param

XSLT Extras: sort, copy-of, document…

Why/When XSLT?

3

The X* Ecosystem

• XSL(T): Extensible Stylesheet Language (Transforms)– Like a giant function with a domain of XML and a

range of XML, HTML and Text– XSL-FO (Formatting Objects) is a related,

graphics/print-oriented language• XPath: XML Path (addressing)– Like a filesystem path in an XML document– Also like RegEx– a language for navigating in XML documents

4


XML Nodes Processing instruction: <?pi ... ?> Element: <element /> or

<element></element> Attribute: <element attribute="value" /> Comment:  Entity: & Text node (just plain text)

5


XML Syntax Rules Escape < > & (turn them into entities <

> &) Every document has exactly one root element Attribute values are always quoted Elements are case-sensitive (and are typically

lowercase) You don't have to put an xml processing

instruction at the top of your document

6

XPath: Addresses for XML

XPath Expressions/library

/library/book

/library/book/@name

/library/book[@name="The Fourth Civilization"]

/library/book[1]

//book[2]

<library>

<book name="C++ How to Program" />

<book name="The Fourth Civilization" />

</library>

7



/library/book

/library/book/@name


/library/book[1]

//book[2]

<library>



</library>

8



/library/book

/library/book/@name


/library/book[1]

//book[2]

<library>



</library>

9



/library/book

/library/book/@name


/library/book[1]

//book[2]

<library>



</library>Predicate

10



/library/book

/library/book/@name


/library/book[1]

//book[2]

<library>



</library>

11



/library/book

/library/book/@name


/library/book[1]

//book[2]

<library>



</library>

12


XPath Node selectors

/library/*

/library/book[1]/text()

/library/node()[1]

.

<library>

<book>The Principles

of Computer Hardware</book>


</library>

13



/library/*


/library/node()[1]

.

<library>




</library>

14



/library/*


/library/node()[1]

.

<library>




</library>

15



/library/*


/library/node()[1]

.

<library>




</library>

Selects the "current" node

16


XPath Axes/library/child::book

(or /library/book for short)

/descendent-or-self::book(or //book for short)

//book[1]/parent::*(or //book[1]/.. for short)

//book[2]/preceding-sibling::book

//book[1]/attribute::name(or //book[1]/@name for short)

<library>



</library>

17








<library>



</library>

18








<library>



</library>

19








<library>



</library>

20








<library>



</library>

21


XPath Functions//book[last()]

count(//book)

name(/*)

//book[contains(@name, "C++")]

//book[not(contains(@name, "C++"))]

<library>



</library>

22



count(//book)

name(/*)



Returns: 2<library>



</library>

23



count(//book)

name(/*)



Returns: "library"<library>



</library>

24



count(//book)

name(/*)



<library>



</library>

25



count(//book)

name(/*)



<library>



</library>

26


Other Useful XPath Functionsposition() – provides the position in a list (nice for numbering a

sequence of nodes)

sum(xpath) – takes a sequence of nodes and adds up their numerical values – see also avg(), min(), max()

concat(string, string, …) – exactly what you think

string-length(string) – returns the number of characters

substring(string, start[, length]) – the first char is at 1

translate(source-string, find-string, replace-string) – looks for individual chars and replaces themExample: translate("ABCD", "BD", "bd") "AbCd"

27


XPath Operators//book[last() or

contains(@name, "C++")]

//book[string-length(@name) > 5]

//book[1] | //book[2]

Other operators:

and, =, >, <=, >=, !=, +, -, *, div, mod

Don't forget to escape < >!

<library>



</library>

28





//book[1] | //book[2]

Other operators:

and, =, >, <=, >=, !=, +, -, *, div, mod


<library>



</library>

29





//book[1] | //book[2]

Other operators:

and, =, >, <=, >=, !=, +, -, *, div, mod


<library>



</library>

30





//book[1] | //book[2]

Other operators:

and, =, >, <=, >=, !=, +, -, *, div, mod


<library>



</library>

31

XSLT Basics

• Try it out– Make an XML file– Make an XSLT file– Run the transform and view the transformed data

<xml />input

<xsl:… />transform

<xml />(or text)output

• <xsl:template> Element– It details what items from the source document it should handle

and uses its content to specify what should be added to the output when it is executed

– match attribute is used to associate a template with an XML element and define a template for the entire document. E.g emptyXSL.xsl

• <xsl:value-of> Element– used to evaluate an expression and add the result to the output– used to extract the value of an XML element and add it to the

output stream of the transformation• <xsl:for-each> Element– used to select every XML element of a specified node-set

• <xsl:apply-templates> Element– responsible for deciding which items in the source document

should be processed; they are then handled by the appropriate template

33

XSLT Basics

Sample XML<person>

<name first="Neil" last="Armstrong" /><quote>...one giant leap for mankind.</quote>

</person>

Sample OutputNeil Armstrong said "...one giant

leap for mankind."

Sample XSLT<xsl:stylesheet version="1.0" xmlns:xsl=

"http://www.w3.org/1999/XSL/Transform"><xsl:output method="text" /><xsl:template match="/person">

<xsl:value-of select="concat(name/@first, ' ', name/@last)" />

said "<xsl:value-of

select="quote" />"</xsl:template>

</xsl:stylesheet>

34

XSLT Basics

Sample XML<person>


</person>


leap for mankind."




said "<xsl:value-of


</xsl:stylesheet>

35

XSLT Basics

Sample XML<person>


</person>


leap for mankind."




said "<xsl:value-of


</xsl:stylesheet>

36

XSLT Basics

Sample XML<person>

<name first="Neil" last="Armstrong" /><quote>...one giant leap for mankind. </quote>

</person>

Sample Output<html><head><title>Neil

Armstrong</title></head>

<body><blockquote>…one giant leap for mankind.</blockquote>

</body></html>

Sample XSLT HTML<xsl:stylesheet version="1.0" xmlns:xsl=

"http://www.w3.org/1999/XSL/Transform"><xsl:output method="html" /><xsl:template match="/person">

<html><head><title><xsl:value-of select="concat(

name/@first, ' ', name/@last)" />

</title></head><body><blockquote><xsl:value-of

select="quote" /></blockquote></body></html>

</xsl:template></xsl:stylesheet>

All well-formed

37

XSLT Basics

Sample XML<person>


</person>

Sample Output<html><head><title>Neil

Armstrong</title></head>

<body><blockquote>…one giant leap for mankind.</blockquote>

</body></html>


"http://www.w3.org/1999/XSL/Transform"><xsl:output method="html" /><xsl:template match="/person">

<html><head><title><xsl:value-of select="concat(

name/@first, ' ', name/@last)" />

</title></head><body><blockquote><xsl:value-of

select="quote" /> </blockquote></body></html>


38

XSLT Basics

Sample XML<person>


</person>

Sample Output<quote><speaker firstname="Neil"

lastname="Armstrong"/> <text>…one giant leap for mankind.</text>

</quote>

Sample XSLT XML<xsl:stylesheet version="1.0" xmlns:xsl=

"http://www.w3.org/1999/XSL/Transform"><xsl:output method="xml" /><xsl:template match="/person">

<quote><speaker firstname="{name/@first}" lastname="{name/@last}"/>

<text><xsl:value-of select="quote" /></text>

</quote></xsl:template>

</xsl:stylesheet>

39

XSLT Basics

Sample XML<person>


</person>



</quote>






</xsl:stylesheet>

40

XSLT Basics

Sample XML<person>


</person>



</quote>






</xsl:stylesheet>

41

XSLT Loops: for-each

Sample XML<zoo>

<birds><albatross

pop="4" /><buzzard

pop="2" /><chickadee

pop="12" /></birds><mammals>

<aardvark pop="5" />

<bat pop="200" /><cheetah

pop="2" /></mammals>

</zoo>


"http://www.w3.org/1999/XSL/Transform"><xsl:output method="html" /><xsl:template match="/zoo">

<html><head><title>Zoo</title></head><body>

<xsl:for-each select="*">

<h1><xsl:value-of select="name(.)" />

</h1></xsl:for-each></body></html>


42


Sample XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>

Result HTML<html><head><title>Zoo</title>

</head><body><h1>

birds</h1><h1>

mammals</h1>

</body></html>

43


Sample XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>


"http://www.w3.org/1999/XSL/Transform"><xsl:output method="html" /><xsl:template match="/zoo">

<html><head><title>Zoo</title></head><body>

<xsl:for-each select="*"><h1><xsl:value-of select="name(.)" /></h1>

<ul><xsl:for-each select="*"><li><xsl:value-of select="name(.)" /> (<xsl:value-of select="@pop">)</li>

</xsl:for-each></ul></xsl:for-each></body></html>


44


Sample XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>

Result HTML<html><head><title>Zoo</title>

</head><body>

<h1>birds</h1><ul>

<li>albatross (4)</li> …</ul>

<h1>mammals</h1><ul>

<li>aardvark (5)</li>…

</ul></body></html>

45

XSLT Loops: apply-templates

<xsl:template match="birds | mammals">

<h1><xsl:value-of select="name(.)" /></h1><ul>

<xsl:for-each select="*"><li><xsl:value-of select="name(.)" /> (<xsl:value-of select="@pop"/>)</li>

</xsl:for-each></ul>


Sample XSLT <xsl:stylesheet version="1.0" xmlns:xsl=

"http://www.w3.org/1999/XSL/Transform"><xsl:output method="html" />

<xsl:template match="/zoo"><html><head><title>Zoo</title></head><body>

<xsl:apply-templates select="*" />

</body></html>

</xsl:template>

46

XSLT Decisions: if

XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>

XSLT…<xsl:template match="birds | mammals">

<h1><xsl:value-of select="name(.)" /> </h1><p>We have more than 2...</p><xsl:if test="*[@pop > 2]">

<ul>

<xsl:for-each select="*[@pop > 2]"><li><xsl:value-of select="name(.)" /></li>

</xsl:for-each></ul>

</xsl:if></xsl:template>…

47

XSLT Decisions: if

Sample XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>

Result HTML<html><head><title>Zoo</title></head><body>

<h1>birds</h1><p>We have more than 2...</p><ul>

<li>albatross</li><li>chickadee</li>

</ul>

<h1>mammals</h1><p>We have more than 2...</p><ul>

<li>aardvark</li><li>bat</li>

</ul></body></html>

48

XSLT Decisions: choose

XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>

XSLT fragment<xsl:template match="birds | mammals">

<ul><xsl:for-each select="*">

<li><xsl:value-of select="name(.)" />(<xsl:choose>

<xsl:when test="@pop = 2">a couple</xsl:when>

<xsl:when test="@pop <= 5">a few</xsl:when>

<xsl:otherwise>many</xsl:otherwise></xsl:choose>)

</li></xsl:for-each></ul>

</xsl:template>

49

XSLT Decisions: choose

Sample XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>


<ul><li>albatross (a few)</li><li>buzzard (a couple)</li><li>chickadee (many)</li>

</ul><ul>

<li>aardvark (a few)</li><li>bat (many)</li><li>cheetah (a couple)</li>

</ul></body></html>

50

XSLT Variables: variable

XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>


<xsl:variable name="total-animals" select="sum(*/@pop)" />


<li><xsl:value-of select="name(.)" />(<xsl:value-of select="round(100 * @pop div $total-animals)"/>% of all <xsl:value-of select="name(..)"/>)


</xsl:template>

51

XSLT Variables: variable

Source XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>


<ul><li>albatross (22% of all birds)</li><li>buzzard (11% of all birds)</li><li>chickadee (67% of all birds)</li>

</ul><ul>

<li>aardvark (2% of all mammals)</li><li>bat (97% of all mammals)</li><li>cheetah (1% of all mammals)</li>

</ul></body></html>

52

XSLT Variables: parameter

<xsl:template name="animal">

<xsl:param name="total" /><li>

<xsl:value-of select="name(.)" /> (<xsl:value-of select="round(100 * @pop div $total)"/>%)

</li></xsl:template>

XSLT fragments<xsl:template match="birds | mammals"><xsl:variable name="total-animals" select="sum(*/@pop)" />

<ul><xsl:for-each select="*"><xsl:call-template name="animal"><xsl:with-param name="total" value="$total-animals">

</xsl:call-template></xsl:for-each></ul>

</xsl:template>

53

XSLT Variables: param

<xsl:template name="animal">

<xsl:param name="total" /><li>

<xsl:value-of select="name(.)" /> (<xsl:value-of select="round(100 * @pop div $total)"/>%)

</li></xsl:template>

XSLT fragments<xsl:template match="birds | mammals"><xsl:variable name="total-animals" select="sum(*/@pop)" />

<ul><xsl:for-each select="*"><xsl:call-template name="animal"><xsl:with-param name="total" value="$total-animals">

</xsl:call-template></xsl:for-each></ul>

</xsl:template>

54


XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>

XSLT fragment<xsl:param name="minimum-population" select="5" /><xsl:template match="birds | mammals">

<ul>

<xsl:for-each select="*[@pop >= $minimum-population]">

<li><xsl:value-of select="name(.)" />(<xsl:value-of select="@pop"/>)


</xsl:template>

55


Source XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>


<ul><li>chickadee (12)</li>

</ul><ul>

<li>aardvark (5)</li><li>bat (200)</li>

</ul></body></html>

56

XSLT Extras: sort

XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>



<xsl:sort select="@pop" order="descending" data-type="number" />

<li><xsl:value-of select="name(.)" />

(<xsl:value-of select="@pop"/>)</li>

</xsl:for-each></ul></xsl:template>

57

XSLT Extras: sort

Source XML<zoo>

<birds><albatross

pop="4" /><buzzard






</zoo>


<ul><li>chickadee (12)</li><li>albatross (4)</li><li>buzzard (2)</li>

</ul><ul>

<li>bat (200)</li><li>aardvark (5)</li><li>cheetah (2)</li>

</ul></body></html>

58

XSLT Extras: copy-of

Source XML<person>


</person>

XML Output<quote><name first="Neil"

last="Armstrong"/> <text>…one giant leap for mankind.</text>

</quote>



<quote><xsl:copy-of select="name" />



</xsl:stylesheet>

59

XSLT Extras: more elements

• xsl:text – writes literal text to the output (useful for controlling whitespace or forcing exact, unescaped output)

• xsl:processing-instruction – writes a PI like <?php… ?> or <?xml-stylesheet… ?> to the output

• xsl:import and xsl:include – used to combine stylesheets (useful for XSLT libraries)

60

XSLT Extras: more functions

• document(url) – opens an XML document at the given location, returning its nodes as data that can be used by the templateExample: document('zoo.xml')/zoo//*[@pop = 2]

• current() – similar to "." except that it always refers to the current node, even when used inside predicatesExample://*[@pop = current()/@pop]

61

XSLT Extras: xml-stylesheet

To make an XML document show itself in a transformed format, add this to the top:<?xml-stylesheet type="text/xsl"

href="path/to/transform.xslt" ?>

This is particularly useful for XML like RSS

62

Why/When XSLT?

Web Standard

XSLT v 1.0 Recommended by W3C almost 10 years ago (it's stable and well understood)

Dozens of implementations and host languages (Java, .NET, PHP, C++…)

Wide tool support (Firefox, IE, Visual Studio, many text editors, full IDEs…)

No vendor lock-in

63

Why/When XSLT?

Very good at converting XML to XML, XHTML/HTML, or plain textMakes it easy to keep things well-formed

Uses XML syntax, so the only real new syntax is XPath (which is also used elsewhere)

XPath is far more compact than similar DOM code in JS/Java/C#/etc.

Can be interpreted (for quick development) or compiled (for maximum performance)

introductionto xslt

Education