XSLT for Data Manipulation

1. XSLT for Data Manipulation By: April Fleming

2. 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

3. 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

4. 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”

5. What is XSLT - cont’d • These “rules” have two parts • Pattern • Matched against nodes in the source tree • Template • Can be instantiated to form part of the result tree

6. 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

7. Output Formats • <xsl:output> • Optional • Parser 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

8. Output Format - cont’d • Three types of output • XML • <xsl:output method=”xml” /> • output is an XML document or XML document fragment • <?xml version="1.0"?>appears in the resulting output

9. Output Formats - Cont’d • HTML • <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

10. Why would I use XSLT • XSLT is a supported w3c standard. • XSLT Provides the traditional language conventions that we are used to when processing data • Looping • Conditional Logic • Expressions • Variables

11. Why would I use XSLT - cont’d • Dynamic • Efficient • Facilitate separation of Data and Presentation

12. 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.

13. How I used XSLT and Why • I chose XML as the data format for I/O to the engine • Uniform structure of Data regardless of the source • Data could be easily parsed using XML parser

14. How I used XSLT and Why - cont’d • I chose XSLT to process the XML data going into and out of the search engine • With 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

18. 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

19. What tools will I need to use XSLT? • XML Parser • MSXML • 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

20. XML Parser Comparison Chart

21. Simple “Hello World” example • To perform a transformation we need three things • XML Data • XSLT Stylesheet • XML Parser

23. XML Data - Save as hello.xml • <?xml version="1.0" ?> • <output>Hello World</output>

24. 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>

25. 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">

26. <cfscript> //do not validate the xml xml.validateOnParse=false; xml.async = false; //load the xml file into the xml instance of the parser temp = xml.load("c:\inetpub\wwwroot\hello.xml");</cfscript><cfscript> xsl.async=false; //load the xsl file into the xsl instance of the parser xsl.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 = "">

27. 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 synonymfor <xsl:stylesheet> either one is acceptable

28. 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

29. 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="..."/>

30. 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>

31. 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

32. 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>

33. Templates - cont’d • <xsl:template match=”Chapter/@title”> • matches the title attribute of the chapter node <chapter title=”my title” … </chapter>

34. 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>

35. <xsl:apply-templates> • For each child of the current node • Find the matching template rule • Instantiate the template rule <xsl:template match=“/”> <xsl:apply-templates/> </xsl:template>

36. <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>

37. <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>

38. XSLT: <xsl:for-each select=“oranges”> … </xsl:for-each> ColdFusion: <cfloop list=“#oranges#”> … </cfloop> <xsl:for-each> - Looping

39. 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> <xsl:if> - Conditional Logic Result: Bob, Mary, John, Martha, Sue

40. 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:choose> - Conditional Logic

41. <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

42. 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

43. 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”/>

44. 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.