Difference between revisions of "XSLT"

Latest revision as of 07:02, 15 March 2021

eXtensible Stylesheet Language Translation is act of applying a specially formatted file which contains an XSL translation specification for the content of a particular XML file, translating the context from raw XML format into a formatted HTML page (or other application/GUI element or format, such as a different XML, extending basic XML up to RDF or simplifying XML down to CSV or plaintext values).

Specifications

XSLT: http://www.w3.org/TR/xslt | v1.1 | v2.0 | v3.0
XQuery 1.0 and XPath 2.0 Functions and Operators: http://www.w3.org/TR/xpath-functions/
XSLT Security: https://docs.microsoft.com/en-us/previous-versions/windows/desktop/ms763800(v=vs.85)

Structure

The structure of an XSLT requires three parts:

A well-formed XML document we want to parse
An XSL file for grabbing the desired data from the XML document and performing the transformation
A target HTML file with a particular look & feel we want to generate and present to the end-us

These three components and the flow of a typical transformation is nicely summarized in the following diagram:

Transforming an XML document to HTML

EXAMPLES

Match

For example, with the following XML document for defining a shareable Contact list:

 <?xml version="1.0" encoding="UTF-8" ?>
 <AddressBook>
   <contact type="friend">
     <name>Phil Hart</name>
     <title>Social Worker, Federal Government of Countria</title>
     <email>phil.hart@countria.gov</email>
     <phone extension="3490">+23 (81) 892-2387</phone>
   </contact>
   <contact type="boss">
     <name>John Doe</name>
     <title>CEO, Company Inc.</title>
     <email>john.doe@company.com</email>
     <phone>+1 (123) 456-7890</phone>
   </contact>   
   <contact type="friend">
     <name>Barb Boe</name>
     <title>Secretary, Company Z Inc.</title>
     <email>barb.boe@companyz.com</email>
     <phone>+1 (98) 765-4321</phone>
   </contact>  
   ... 
 </AddressBook>

We can extract the information of each friend only, leaving out co-workers, colleagues, etc via the following XSL:

 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0" xmlns="http://www.w3.org/1999/xhtml">
   <xsl:template match="contact[@type='friend']">
     <html xmlns="http://www.w3.org/1999/xhtml">
       <title>business card</title>
       <body>
         <ul>
           <xsl:apply-templates select="name"/>
           <xsl:apply-templates select="title"/>
           <xsl:apply-templates select="email"/>
           <xsl:apply-templates select="phone"/>
         </ul>
     </body>
     </html>
   </xsl:template>
   <xsl:template match="contact/name">
     <li>
     <h1><xsl:value-of select="text()"/></h1>
   </xsl:template>
   <xsl:template match="title">
     occupation: <h3><xsl:value-of select="text()"/></em></h3>
   </xsl:template>
   <xsl:template match="email">
     <p>email: <a href="mailto:{text()}"><tt><xsl:value-of select="text()"/></tt></a></p>
   </xsl:template>
   <xsl:template match="phone">
     <xsl:variable name="contactphone" select='text()' />
     <xsl:variable name="extension" select='@extension' />
      <xsl:variable name="thephone">
        <xsl:call-template name="replaceCharsInString">
          <xsl:with-param name="stringIn" select="string($thephone)"/>
          <xsl:with-param name="charsIn" select=" "/>
          <xsl:with-param name="charsOut" select="-"/>
        </xsl:call-template>
      </xsl:variable> 
      <xsl:variable name="formatphonenum">
        <xsl:call-template name="replaceCharsInString">
          <xsl:with-param name="stringIn" select="string($thephone)"/>
          <xsl:with-param name="charsIn" select="("/>
          <xsl:with-param name="charsOut" select=""/>
        </xsl:call-template>
      </xsl:variable> 
      <xsl:variable name="phonenum">
        <xsl:call-template name="replaceCharsInString">
          <xsl:with-param name="stringIn" select="string($formatphonenum)"/>
          <xsl:with-param name="charsIn" select=")"/>
          <xsl:with-param name="charsOut" select=""/>
        </xsl:call-template>
      </xsl:variable>
     <xsl:choose>
      <xsl:when test="extension !=null">        
        <p>phone#: <a href="tel:{phonenum}"><xsl:value-of select="phonenum"/>ext. <xsl:value-of select="extension" /></a></p>
      </xsl:when>
      <xsl:otherwise>
        <p>phone#: <a href="tel:{phonenum}"><xsl:value-of select="phonenum"/></a></p>
      </xsl:otherwise>
     </xsl:choose>
     <li>
   </xsl:template>

   <!-- a useful template for string replacement -->
      <xsl:template name="replaceCharsInString">
        <xsl:param name="stringIn"/>
        <xsl:param name="charsIn"/>
        <xsl:param name="charsOut"/>
        <xsl:choose>
          <xsl:when test="contains($stringIn,$charsIn)">
            <xsl:value-of select="concat(substring-before($stringIn,$charsIn),$charsOut)"/>
            <xsl:call-template name="replaceCharsInString">
              <xsl:with-param name="stringIn" select="substring-after($stringIn,$charsIn)"/>
              <xsl:with-param name="charsIn" select="$charsIn"/>
              <xsl:with-param name="charsOut" select="$charsOut"/>
            </xsl:call-template>
          </xsl:when>
          <xsl:otherwise>
            <xsl:value-of select="$stringIn"/>
          </xsl:otherwise>
        </xsl:choose>
      </xsl:template>
 </xsl:stylesheet>

(NOTE: this is a little more complicated because it also reformats some of the data to make a telephone number follow the tel protocol)

In order to call a stylesheet for rendering an XML file's data, simply add the following directive to the XML file directly below the header:

<?xml-stylesheet type="text/xsl" href="contacts.xsl"?>

This will output the following HTML to be displayed in the user's browser:

 <html xmlns="http://www.w3.org/1999/xhtml">
 <title>Address Book</title>
 <body>
   <ul>
     <li>
       <h1>Phil Hrat</h1>
       <h3><em>Social Worker, Federal Government of Countria</em></h3>
       <p>email: <a href="mailto:phil.hart@countria.gov"><tt>phil.hart@countria.gov</tt></a></p>
       <p>phone: <a href="tel:+23-1-81-892-2387,3490">+23 (81) 892-2387 ext.3490</a></p>
     </li>
     <li>
       <h1>Barb Boe</h1>
       <h3><em>Secretary, Company Z Inc.</em></h3>
       <p>email: <a href="mailto:barb.boe@companyz.com"><tt>barb.boe@companyz.com</tt></a></p>
       <p>phone: <a href="tel:+1-98-765-4321">+1 (81) 892-2387</a></p>
     </li>
     ...
   </ul>
 </body>
 </html>

^[1]

Functions

There are a number of additional functions available in all XSLT 2.0-compatible processing/transformation engines.

XSLT 2.0 Functions: http://www.xsltfunctions.com/ (a summary of functions with examples)^[2]^[3]

In the following example, we extract the characters which occur before a space (i.e. first word in the matched data) for TITLE and the six characters which occur after the fourth character (i.e. last name of the artis):

 <?xml version="1.0" encoding="UTF-8"?>
 <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:template match="/">
  <html>
  <body>
    <h2>My CD Collection</h2>
    <table border="1">
      <tr bgcolor="#9acd32">
        <th>Title</th>
        <th>Artist</th>
      </tr>
      <tr>
        <td><xsl:value-of select="substring-before(/catalog/cd/title,' ')"/></td>
        <td><xsl:value-of select="substring(/catalog/cd/artist, 4, 6)"/></td>
      </tr>
    </table>
  </body>
  </html>
 </xsl:template>
 </xsl:stylesheet>

To apply the same (admittedly odd in this case) string operations to all items in the XML, it would become:

 <?xml version="1.0" encoding="UTF-8"?>
 <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:template match="/">
  <html>
  <body>
    <h2>My CD Collection</h2>
    <table border="1">
      <tr bgcolor="#9acd32">
        <th>Title</th>
        <th>Artist</th>
      </tr>
      <xsl:for-each select="catalog/cd">
      <tr>
        <td><xsl:value-of select="substring-before(title,' ')"/></td>
        <td><xsl:value-of select="substring(artist, 4, 6)"/></td>
      </tr>
      </xsl:for-each>
    </table>
  </body>
  </html>
 </xsl:template>
 </xsl:stylesheet>

^[4] (NOTE: to perform the same string operations on ALL

xsltproc

The XSLT processing tool (xsltproc) can be used to convert/transform any XML file, whether you have a specific XSLT or not.

For instance, to convert an XML file when you don't have a specific XSLT you can get the :

xsltproc input.xml -o output.html

Whereas if you have a specific XSLT to process the source XML data with, use:

xsltproc transformer.xsl input.xml > output.xml

^[5] ^[6]

Tools

XSLT Fiddle: https://xsltfiddle.liberty-development.net/3Nqn5Yp
JS Transformer: http://bcmoney-mobiletv.com/blog/2010/12/08/js-transformer/

XSLT Generator

XSLTGen -- An Automatic XSLT Stylesheet Generator: http://ww2.cs.mu.oz.au/~jbailey/xsltgen/XSLTGen.htm
XSLT Tester: http://www.perfectxml.com/xsltester.asp (IE-only for client-side)

XSL Transformation Service

Online XSLT: http://www.w3.org/2005/08/online_xslt/
W3C XSLT (auto-transformation) service: http://www.w3.org/2000/06/webdata/xslt (same as above, only can be used directly as a Transformation Web Service)
In-line XSLT processor: http://chris.photobooks.com/xml/default.htm
W3schools -- Online XSLT Editor: http://www.w3schools.com/xsl/tryxslt.asp?xmlfile=cdcatalog&xsltfile=cdcatalog

EXAMPLE #1 - Amazon Web Services SOAP v1

EXAMPLE #2 - Amazon Web Services SOAP v2

Resources

XSLT Standard Library: http://xsltsl.sourceforge.net/
XSLTV: http://ericandchar.com/xsltvgrid/
A simple FOR loop in XSLT: http://snippets.dzone.com/posts/show/930
XSLT - file for scraping RDF Semantics from xHTML files: http://lists.w3.org/Archives/Public/w3c-wai-er-ig/2001Jun/att-0017/rdfs2xhtml.xsl
XSLT - file for converting from RDFS to xHTML: http://weborganics.co.uk/stylesheets/rdfs-xhtml.xsl
XML-to-string converter: http://lenzconsulting.com/xml-to-string/

Java

XSLT Processing with Java: http://onjava.com/pub/a/onjava/excerpt/java_xslt_ch5/index.html
TransformUtil.java: http://java.codefetch.com/cache?url=http://www.apress.com/ApressCorporate/supplement/1/460/1590595203-2919.zip&path=jcb_package/src/jcb/util/TransformUtil.java

JavaScript

Using the Mozilla JavaScript interface to XSL Transformations: https://developer.mozilla.org/en/Using_the_Mozilla_JavaScript_interface_to_XSL_Transformations

AJAXSLT

AJAXSLT is an implementation of XSL-T in JavaScript, intended for use in fat web pages, which are nowadays referred to as AJAX applications. Because XSL-T uses XPath, it is also an implementation of XPath that can be used independently of XSL-T.