XSLT for Data Manipulation

By: April Fleming

What We Will Cover

• The What, Why, When, and How of XSLT

• What tools you will need to get started

• A sample “Hello World” application

• Enough XSLT Constructs to get started, given from a ColdFusion point-of-view

What is XSLT

• eXstensible Stylesheet Language: Transformations

• Transformation Language

• High-Level data manipulation language

• A language for transforming the structure of an XML document

• Primarily designed by the W3C for transforming one XML document into another

What is XSLT - cont’d

• The XSLT language is expressed as a well-formed XML document

• The XSLT language belongs to the XSLT Namespace

• An XSLT transformation describes rules for transforming a source tree into a result tree. This set of rules is called a “stylesheet”

What is XSLT - cont’d

• These “rules” have two partsPattern

• Matched against nodes in the source tree

Template• Can be instantiated to form part of the result

tree

What is XSLT - cont’d

• The result tree is separate from the source tree

• The result tree can be in a completely different form from the source tree

Output Formats

• <xsl:output>OptionalParser will default the output type if the tag

is omitted.

• Top-Level Element used to define the output type desired

• Enables you to specify encoding for output

Output Format - cont’d

• Three types of outputXML

• <xsl:output method=”xml” />

• output is an XML document or XML document fragment

•<?xml version="1.0"?> appears in the resulting output

Output Formats - Cont’dHTML

• <xsl:output method=”html” version=”4.0” />

• Output is an HTML document

Text• Allows output in many other text-based formats

• Comma-seperated values

• RTF

• PDF

• EDI

• SQL

• Javascript

Why would I use XSLT

• XSLT is a supported w3c standard.

• XSLT Provides the traditional language conventions that we are used to when processing dataLoopingConditional LogicExpressionsVariables

Why would I use XSLT - cont’d

• Dynamic

• Efficient

• Facilitate separation of Data and Presentation

How I used XSLT and Why

• Distributed Search Application

• I needed to write a search engine that could function independent of the various search interfaces that we had.

• I needed the engine to be completely independent of the search interfaces or the search result displays.

How I used XSLT and Why

• I chose XML as the data format for I/O to the engineUniform structure of Data regardless of the

sourceData could be easily parsed using XML

parser

How I used XSLT and Why - cont’d

• I chose XSLT to process the XML data going into and out of the search engineWith XSLT I could easily transform the

data defintion output packets from the engine and create an html search form

I also found XSLT to be a great way to take the search results and transform them into the various display formats we offered to our users

When would I use XSLT?

• When you have XML data from a source (external or internal) with no other way to process that data

• When the XSLT transformations are faster than the current way you have to process your XML data.

• Example: XSLT vs. CF processing

• When you need more power and flexibility than your current XML processing mechanism provides

• Example: CF MX XML Processing Tags/Functions

• XML ParserMSXML

• This is the Parser that I used

• Free download from Microsoft

• Excellent Documentation

• http://msdn.microsoft.com/xml/default.asp

Other Parsers - see chart on next slide

• Good understanding of XPath• Used for XSLT expressions

• MSXML SDK - good Xpath documentation

What tools will I need to use XSLT?

XML Parser Comparison ChartIBM XML4J

Apache XercesSun Project

XMicrosoftMSXML

Oracle XMLParser for Java

JamesClark XP

well-formednesschecking

+ + + + +

validating + + + + -

XML-Schema + - - - -

Namespaces + + + + -

XSL-TwithLotusXSL

- + + -

Java + + - + +

Win32 through Java through Java through Java + -

SAX 1.0 + + + + +

SAX 2.0 + - + - -

DOM Level 1 1.0 + + + + -

DOM Level 2 1.0 + - - - -

Open Source + - - - +

DownloadXML4JXerces

ProjectX MSXML ORA XP

• To perform a transformation we need three thingsXML DataXSLT StylesheetXML Parser

Simple “Hello World” example

XML Data - Save as hello.xml

• <?xml version="1.0" ?>

• <output>Hello World</output>

XSLT Stylesheet – Save as hello.xsl

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

<xsl:template match=”/”>

<html>

<head>

<title> XSLT Example</title>

</head>

<body>

<xsl:value-of select=”output” />

</body>

</html>

</xsl:template>

</xsl:stylesheet>

Parsing – ColdFusion & MSXML Parser

<!---Create two instances of the XML Parser, one for the XML and one for the XSL--->

<cfobject type = "COM" action = "create" class = "MSXML2.DOMDOCUMENT.4.0" name = "xml">

<cfobject type = "COM" action = "create" class = "MSXML2.DOMDOCUMENT.4.0"

name = "xsl">

<cfscript>//do not validate the xmlxml.validateOnParse=false;

xml.async = false;//load the xml file into the xml instance of the parsertemp = xml.load("c:\inetpub\wwwroot\hello.xml");

</cfscript><cfscript>

xsl.async=false;//load the xsl file into the xsl instance of the parserxsl.load("c:\inetpub\wwwroot\hello.xsl");

output = xml.transformNode(xsl);</cfscript>

<!---output the transformed result----><cfoutput>#output#</cfoutput>

<!---set com objects to null---><cfset xml = ""><cfset xsl = "">

XSLT Stylesheet Structure

The XSLT namespace has the URI http://www.w3.org/1999/XSL/Transform.

<xsl:stylesheetxmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">

• Remember that an XSLT stylesheet is a well-formed XML document, therefore you must always include the corresponding closing tag.

• </xsl:stylesheet>

• The tag <xsl:transform> is a synonym for <xsl:stylesheet> either one is acceptable

XSLT Stylesheet Structure - cont’d

Can use any prefix, provided that there is a namespace declaration that binds the prefix to the URI of the XSLT namespace

• An element occurring as a child of an xsl:stylesheet element is called a top-level element

Top Level Elements

• <xsl:import href="..."/>

• <xsl:include href="..."/>

• <xsl:strip-space elements="..."/>

• <xsl:preserve-space elements="..."/>

• <xsl:output method="..."/>

• <xsl:key name="..." match="..." use="..."/>

• <xsl:decimal-format name="..."/>

Top Level Elements - cont’d

• <xsl:namespace-alias stylesheet-prefix="..." result-prefix="..."/>

• <xsl:attribute-set name="..."></xsl:attribute-set>

• <xsl:variable name="...">...</xsl:variable>

• <xsl:param name="...">...</xsl:param>

• <xsl:template match="..."></xsl:template>

• <xsl:template name="..."></xsl:template>

Templates• <xsl:template match=””>

• “Match” is a pattern, the pattern is expressed using Xpath

• Pattern describes which nodes in the source tree the template rule matches

• <xsl:template match=”/” >matches the root node

• <xsl:template match=”Title” >matches the title node

Templates - cont’d

• <xsl:template match=”Chapter/Title”>matches the Title node that is a child to

the Chapter node

<chapter>

<title>My Title</title>

</chapter>

Templates - cont’d

• <xsl:template match=”Chapter/@title”>matches the title attribute of the chapter

node

<chapter title=”my title”

…

</chapter>

Templates - cont’d

• When the template is instantiated (a match condition is met), the instructions within the template tags are executed and the resulting data is copied to the result tree.

<xsl:template match=”/”>

….instructions….

</xsl:template>

<xsl:apply-templates>

• For each child of the current nodeFind the matching template ruleInstantiate the template rule

<xsl:template match=“/”><xsl:apply-templates/>

</xsl:template>

<xsl:apply-templates select=“”>

• Allows you to control the order that template rules are applied

<xsl:template match=“/”><xsl:apply-templates select=“apples”/><xsl:apply-templates select=“oranges”/><xsl:apply-templates select=“banannas”/>

</xsl:template>

<xsl:value-of>

• Extract the required information from the node directly

<xsl:template match=“/”><html>

<head>…</head><body>

<xsl:value-of select=“output”/></body>

</html></xsl:template>

<xsl:for-each> - Looping

XSLT:

<xsl:for-each select=“oranges”>

…

</xsl:for-each>

ColdFusion:

<cfloop list=“#oranges#”>

…

</cfloop>

<xsl:if> - Conditional Logic

XSLT:<xsl:template match="name">

<xsl:value-of select=“.”/>

<xsl:if test="position()!=last()">

,

</xsl:if>

</xsl:template>

ColdFusion:<cfset pos=0>

<cfloop list=“names”Index=“name”>

<cfset pos=incrementValue(pos)>

#name#

<cfif pos neq listlen(names)>

,

</cfif>

</cfloop>

Result:

Bob, Mary, John, Martha, Sue

<xsl:choose> - Conditional Logic

XSLT:<xsl:template match="order">

<xsl:choose> <xsl:when test="total &lt;

5">(small)

</xsl:when> <xsl:when test="total &lt;

10"> (medium) </xsl:when> <xsl:otherwise>

(large) </xsl:otherwise>

</xsl:choose> </xsl:template>

ColdFusion:<cfswitch expression=“order”>

<cfcase value=“1,2,3,4”>(small)

</cfcase><cfcase value=“5,6,7,8,9”>

(medium)</cfcase><cfdefaultcase>

(large)</cfdefaultcase>

</cfswitch>

<xsl:variable> - Variables

XSLT:<xsl:variable name="n" select="2"/>

...<xsl:value-of select="item[$n]"/>

ColdFusion:<cfset n=“2”>#listgetat(list,n)#

• Variables may be defined Globally or Locally• Local variables can be defined within a template body

Datatypes

• Variables are not statically typed, rather they take whatever type of value is assigned to them, just as ColdFusion does

• String• Number• Boolean• Node-Set

A set of nodes in the source tree

• Tree

Expressions

• Syntax of expressions is defined by the XPath Recommendation

• Used as attribute values for many XSLT elements

<xsl:value-of select=“($x + $y) *2”/>

Resources• XSLT – Programmer’s Reference by Michael Kay

(Wrox)*• W3C*

http://www.w3c.org

• Microsoft MSXML SDK Documentation*http://msdn.microsoft.com/library/default.asp?url=/library/en-

us/xmlsdk/htm/sdk_intro_6g53.asp

• XSL-List http://www.mulberrytech.com/xsl/xsl-list

*I have relied heavily on these resources not only for the application development I have done, but also in preparation for this presentation. Many of the information and examples come from one of these sources.