book

XSLT

by Doug Tidwell

August 2001

Intermediate to advanced

480 pages

11h 16m

English

O'Reilly Media, Inc.

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Organization of This Book
I Believe in Open, Platform-Neutral, Standards-Based ComputingI Assume You’re BusyI Don’t Care Which Standards-Compliant Tools You UseXSLT Is a Tool, Not a Religion
The Design of XSLT
XML’s HeritageXML Document RulesAn XML document must be contained in a single elementAll elements must be nestedAll attributes must be quotedXML tags are case-sensitiveAll end tags are requiredEmpty tags can contain the end markerXML declarationsDocument Type Definitions (DTDs) and XML SchemasWell-formed versus valid documentsTags versus elementsNamespacesDOM and SAXDOMA sample DOM treeSAXXML StandardsXML 1.0The Extensible Stylesheet Language (XSL)XML SchemasThe Simple API for XML (SAX)Document Object Model (DOM) Level 1Document Object Model (DOM) Level 2Namespaces in XMLAssociating stylesheets with XML documentsScalable Vector Graphics (SVG)Canonical XML Version 1.0XML digital signaturesXML Pointer Language (XPointer) Version 1.0XML Linking Language (XLink) Version 1.0

Goals of This Chapter
Our Sample DocumentA Sample StylesheetTransforming the XML DocumentStylesheet Results
Parsing the StylesheetParsing the TransformeeLather, Rinse, RepeatWalking Through Our Example
The <xsl:stylesheet> ElementThe <xsl:output> ElementOur First <xsl:template>The <xsl:template> for <greeting> ElementsBuilt-in Template RulesBuilt-in template rule for element and root nodesBuilt-in template rule for modesBuilt-in template rule for text and attribute nodesBuilt-in template rule for comment and processing instruction nodesBuilt-in template rule for namespace nodesTop-Level ElementsOther Approaches
The Hello World SVG FileThe Hello World PDF FileThe Hello World Java ProgramThe Hello World VRML File
The XPath Data ModelThe Root NodeElement NodesAttribute NodesText NodesComment NodesProcessing Instruction NodesNamespace Nodes
The ContextSimple Location PathsRelative and Absolute ExpressionsSelecting Things Besides Elements with Location PathsSelecting attributesSelecting the text of an elementSelecting comments, processing instructions, and namespace nodesUsing WildcardsAxesUnabbreviated syntaxAxis roll callPredicatesNumbers in predicatesFunctions in predicates
Output ViewThe Stylesheet
Goals of This Chapter
The <xsl:if> ElementConverting to boolean valuesBoolean examplesThe <xsl:choose> Element<xsl:choose> exampleThe <xsl:for-each> Element<xsl:for-each> example
How It WorksTemplates à la Mode
Defining a Parameter in a TemplatePassing ParametersGlobal ParametersXalanXTMicrosoft’s XSLT toolsSaxonOracleSetting global parameters in a Java program
Are These Things Really Variables?Variable Scope
Implementing a String Replace FunctionProcedural designRecursive design
Template DesignImplementationThe Complete Example
XML InputTemplate DesignComplications
Generating Links with the id() FunctionThe ID, IDREF, and IDREFs DatatypesAn XML Document in Need of LinksA Stylesheet That Uses the id() FunctionLimitations of IDs
Defining a key()A Slightly More Complicated XML Document in Need of LinksStylesheets That Use the key() FunctionThe key() function and the IDREFS datatypeSolution #1: Replace the IDREFS datatypeSolution #2: Use the XPath contains() functionSolution #3: Use recursion to process the IDREFS datatypeSolution #4: Use an extension functionAdvantages of the key() Function
An Unstructured XML Document in Need of LinksThe generate-id() Function
Sorting Data with <xsl:sort>Our First ExampleThe Details on the <xsl:sort> ElementWhat’s the deal with that syntax?AttributesWhere can you use <xsl:sort>?Another Example
Our First AttemptA Brute-Force ApproachGrouping with <xsl:variable>The <xsl:key> Approach
Overview
An Aside: Doing Math with RecursionRecursive designGenerating output to initialize a variableUsing format-number() to control output
The document() Function and SortingImplementing Lookup TablesGrouping Across Multiple Documents
Extension Elements, Extension Functions, and Fallback ProcessingExtension ElementsExample: Generating multiple output filesExample: Using extension functions from multiple processorsExtension FunctionsExample: A library of trigonometric functionsExample: Writing extensions in other languagesFallback Processing
Generating JPEG Files from XML ContentAccessing a Database with an Extension Element
About the Toot-O-Matic
Make It Easier to Create TutorialsShow Our Audience That We Use the Technologies We AdvocateSee Just How Much We Could Accomplish Through Stylesheets
Menu PanelIndividual PanelsSection MenuFeedback PanelEmail PanelZip FilePDF Files
Individual Panels
Stylesheets and ModesInitializing Global VariablesGenerating the Main Menu PanelGenerating the Section IndexesGenerating the Individual PanelsGenerating the PDF FilesGenerating the JPEG FilesGenerating the Zip File
XPath Node TypesThe Root NodeElement NodesAttribute NodesText NodesComment NodesProcessing-Instruction NodesNamespace Nodes
Mathematical OperatorsBoolean OperatorsComparing values of various datatypesExpression Operators
How Do I Put Quotes Inside an Attribute Value?

Content preview from XSLT

Name

<xsl:fallback> — Defines a template that should be used when an extension element can’t be found.

Required Attributes

None.

Optional Attributes

None.

Content

An XSLT template.

Appears in

<xsl:fallback> appears inside a template.

Defined in

XSLT section 15, Fallback.

Example

Here is a stylesheet that uses <xsl:fallback> to terminate the transformation if an extension element can’t be found:

<?xml version="1.0"?>
<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:db="xalan://DatabaseExtension"
  extension-element-prefixes="db">

  <xsl:output method="html"/>

  <xsl:template match="/">
    <html>
      <head>
        <title><xsl:value-of select="report/title"/></title>
      </head>
      <body>
        <h1><xsl:value-of select="report/title"/></h1>
        <xsl:for-each select="report/section">
          <h2><xsl:value-of select="title"/></h2>
          <xsl:for-each select="dbaccess">
            <db:accessDatabase>
              <xsl:fallback>
                <xsl:message terminate="yes">
                  Database library not available!
                </xsl:message>
              </xsl:fallback> 
            </db:accessDatabase>
          </xsl:for-each>
        </xsl:for-each>
      </body>
    </html>
  </xsl:template>

</xsl:stylesheet>

When we use this stylesheet to transform a document, the <xsl:fallback> element is processed if the extension element can’t be found:

Database library not available!

Processing terminated using xsl:message

In this case, the extension element is the Java class DatabaseExtension. If, for whatever reason, that class can’t be loaded, the <xsl:fallback> element is processed. Note that the <xsl:fallback> element ...