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XSLT

XSLT. Kanda Runapongsa ( krunapon@kku.ac.th ) Dept. of Computer Engineering Khon Kaen University. XSL - The Style Sheet of XML. XML does not use predefined tags (we can use any tags we want) <table> could mean an HTML table, a piece of furniture, or something else

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XSLT

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  1. XSLT Kanda Runapongsa (krunapon@kku.ac.th) Dept. of Computer Engineering Khon Kaen University

  2. XSL - The Style Sheet of XML • XML does not use predefined tags (we can use any tags we want) • <table> could mean an HTML table, a piece of furniture, or something else • XSL: something in addition to the XML document that describes how the document should be displayed 168493: XML and Web Services (II/2546)

  3. What is XSLT? • XSLT transforms an XML document into another XML document, such as an XHTML document • XSLT can • Add new elements into the output file • Remove elements • Rearrange and sort elements • Test and make decisions about which elements to display 168493: XML and Web Services (II/2546)

  4. How Does XSLT Work? • XSLT transforms an XML source tree into an XML result tree • XSLT uses XPath to define parts of the source document that match one or more predefined templates 168493: XML and Web Services (II/2546)

  5. How Does XSLT Work? • When a match is found, XSLT will transform the matching part of the source document into the result document • The parts of the source document that do not match a template will end up unmodified in the result document 168493: XML and Web Services (II/2546)

  6. Style Sheet Declaration • The root element that declares the document to be an XSL sheet is <xsl:stylesheet> or <xsl:transform> • The correct way to declare an XSL style sheet according to the W3C XSL Recommendation is: <xsl:stylesheet version=“1.0”? xmlns:xsl=“http://www.w3.org/1999/XSL/Transform”> 168493: XML and Web Services (II/2546)

  7. XSL Uses Templates • An XSL style sheet consists of a set of rules called templates • Each <xsl:template> element contains rules to apply when a specified node is matched • The match attribute is used to associate the template with a set of XML elements 168493: XML and Web Services (II/2546)

  8. XSL Uses Templates (Cont.) • The match attribute can also be used to define a template for a whole branch of the XML document • Match = “/” defines the whole document • What is another way to select the entire document? • An XSL processor parses an XML source and tries to find a matching template rule. • If it does, instructions inside matching template are evaluated 168493: XML and Web Services (II/2546)

  9. <?xml version="1.0" encoding="ISO-8859-1"?> <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 align="left">Title</th> <th align="left">Artist</th> </tr> <xsl:for-each select="catalog/cd"> <tr> <td><xsl:value-of select="title"/></td> <td><xsl:value-of select="artist"/></td> </tr> </xsl:for-each> </table> </body> </html> </xsl:template> </xsl:stylesheet> Sample XSL File 168493: XML and Web Services (II/2546)

  10. The first lines of the XSL file • <?xml version=“1.0” encoding=“ISO-8859-1”?> • Since the style sheet is an XML document itself, the document begins with an XML declaration • <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> • The <xsl:stylesheet> tag defines the start of the style sheet • Every XSL file needs to specify the XSL namespace so that the parser knows which version of XSLT to use 168493: XML and Web Services (II/2546)

  11. Namespace in XSL <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match=“/”> • The namespace prefix xsl: is used in the rest of the XSL file to identify XSL processing statements • If a statement is not prefixed with xsl:, then it’s simply copied to the output without being processed. This is the way to add HTML statements to the output 168493: XML and Web Services (II/2546)

  12. The <xsl:template> Element • Before processing can begin, the part of the XML document with the transformation must be selected with an XPath expression • The selected section of the document is called a node and is normally selected with the match operator 168493: XML and Web Services (II/2546)

  13. The <xsl:value-of> Element • The <xsl:value-of> element extracts the value of a selected node • Example: <td><xsl:value-of select="catalog/cd/title"/></td> Result: <td>Hide your heart</td> 168493: XML and Web Services (II/2546)

  14. The <xsl:for-each> Element • The <xsl:for-each> element allows you to do looping in XSL • It selects every XML element of a specified node set <xsl:for-each select="catalog/cd"> <tr> <td><xsl:value-of select="title"/></td> <td><xsl:value-of select="artist"/></td> </tr> </xsl:for-each> Selects every ‘catalog/cd’ element 168493: XML and Web Services (II/2546)

  15. Filtering the Output • We can filter the output from an XML file by adding a criterion to the select attribute in the <xsl:for-each> element • <xsl:for-each select=“catalog/cd[artist=‘Bonnie Tyler’]”> 168493: XML and Web Services (II/2546)

  16. The <xsl:sort> Element • The <xsl:sort> element is used to sort the output • To output the XML file as an XHTML file, and sort it at the same time, simply add a sort element inside the for-each element in the XSL file 168493: XML and Web Services (II/2546)

  17. The <xsl:sort> Element <xsl:for-each select="catalog/cd"> <xsl:sort select="artist"/> <tr> <td><xsl:value-of select="title"/></td> <td><xsl:value-of select="artist"/></td> </tr> </xsl:for-each> • The select attribute indicates what XML elements to sort on 168493: XML and Web Services (II/2546)

  18. The <xsl:if> Element • The <xsl:if> element contains a template that will be applied only if a specified condition is true <xsl:if test=“price &gt; 10 “> some output … </xsl:if> • The value of the required test attribute contains the expression to be evaluated 168493: XML and Web Services (II/2546)

  19. The <xsl:choose> Element • The <xsl:choose> element is used in conjunction with <xsl:when> and <xsl:otherwise> to express multiple conditional tests • If no <xsl:when> element is true, and no <xsl:otherwise> element is present, nothing is created 168493: XML and Web Services (II/2546)

  20. The <xsl:choose> Element <xsl:choose> <xsl:when test=“price &gt; 10”> <td bgcolor=“#ff00ff”> <xsl:value-of select=“artist”/></td> </xsl:when> <xsl:otherwise> <td><xsl:value-of select=“artist”></td> </xsl:otherwise> </xsl:choose> 168493: XML and Web Services (II/2546)

  21. The <xsl:apply-templates> Element • The <xsl:apply-templates> element applies a template rule to the current element or to the current element’s child nodes • The <xsl:apply-templates> element is always found inside a template body 168493: XML and Web Services (II/2546)

  22. <xsl:apply-templates> (Cont.) <xsl:template match=“cd”> <p> <xsl:apply-templates select=“title”/> <xsl:apply-templates select=“artist”/> </p> </xsl:template> 168493: XML and Web Services (II/2546)

  23. <xsl:apply-templates/> • The <xsl:apply-templates/>: An instruction to apply templates to the children of the current nodes <xsl:template match="/"> <html> <body> <h2>My CD Collection</h2> <xsl:apply-templates/> … </xsl:template> 168493: XML and Web Services (II/2546)

  24. The <xsl:element> Element • The <xsl:element> element allows an element to be created with a computed name • It generates elements in time of processing <xsl:element name=“course”>168493</xsl:element> 168493: XML and Web Services (II/2546)

  25. The <xsl:attribute> Element • The <xsl:attribute> element can be used to add attributes to result elements whether created by • Literal result elements in the style or • Instructions such as xsl:element <xsl:attribute name=“align”>center</xsl:attribute> 168493: XML and Web Services (II/2546)

  26. The <xsl:copy> Element • The <xsl:copy> element provides an easy way of copying the current node • The namespace nodes of the current node are automatically copied • It may have a use-attribute-set attribute to specify and also copy attributes for copied element 168493: XML and Web Services (II/2546)

  27. <xsl:copy> (Cont.) <xsl:template match=“h1”> <xsl:copy use-attribute-sets=“H1”> <xsl:value-of select=“.”/> </xsl:copy> </xsl:template> • Example <h1 align=“center”>Greeting</h1> 168493: XML and Web Services (II/2546)

  28. The <xsl:copy-of> element • The xsl:copy-of element can be used to insert a result tree fragment into the result tree, without first converting it to string as xsl:value-of does • But when the result is neither a node-set nor a result tree fragment, the result is converted to a string and then inserted into the result tree 168493: XML and Web Services (II/2546)

  29. The <xsl:copy-of> Element <xsl:template match=“/”> <xsl:copy-of select=“/html”/> </xsl:template> XML: <html><h1>Hello</h1></html> Output: <html><h1>Hello</h1></html> 168493: XML and Web Services (II/2546)

  30. The <xsl:output> Element • The <xsl:output> element allows stylesheet authors to specify how they wish the result tree to be output • If an XSLT processor outputs the result tree, it should do so as specified by the <xsl:output> element • However, it is not required to do so 168493: XML and Web Services (II/2546)

  31. The <xsl:output> Element <xsl:stylesheetversion = '1.0'      xmlns:xsl='http://www.w3.org/1999/XSL/Transform'><xsl:outputmethod="html"/> <xsl:templatematch="/">      <xsl:copy-ofselect="/html"/> </xsl:template></xsl:stylesheet> 168493: XML and Web Services (II/2546)

  32. XML source <html> <hr></hr> <hr/> </html> Output (in HTML) <html> <hr> <hr> </html> The <xsl:output> Element 168493: XML and Web Services (II/2546)

  33. The <xsl:output> Element <xsl:stylesheetversion = '1.0'      xmlns:xsl='http://www.w3.org/1999/XSL/Transform'><xsl:outputmethod=“xml"/> <xsl:templatematch="/">      <xsl:copy-ofselect="/html"/> </xsl:template></xsl:stylesheet> 168493: XML and Web Services (II/2546)

  34. XML source <html> <hr></hr> <hr/> </html> Output (in XML) <html> <hr/> <hr/> </html> The <xsl:output> Element 168493: XML and Web Services (II/2546)

  35. The <xsl:number> Element • The <xsl:number> element is used to insert a formatted number into the result tree • The number to be inserted may be specified by an expression • The value attribute contains an expression • If no value attribute is specified, the xsl:number element inserts a number based on the position of the current node 168493: XML and Web Services (II/2546)

  36. <xsl:number> (Cont.) • <xsl:number value=“250000” grouping-separator=“.”/> Output: 250.000 • <xsl:number value=“250000” grouping-size=“2”/> Output: 25,00,00 168493: XML and Web Services (II/2546)

  37. The <xsl:text> Element • Literal data characters may be wrapped in an <xsl:text> element • This wrapping may change what whitespace characters are stripped but does not affect how the characters are handled by the XSLT processor 168493: XML and Web Services (II/2546)

  38. XML source <html> <hr></hr> <hr/> <hr/> </html> Output <html> <hr> <hr> </html> The <xsl:output> Element 168493: XML and Web Services (II/2546)

  39. The <xsl:variable> Element • The <xsl:variable> specify a variable which is a name that may be bound to a value • The value to which a variable is bound (the value of the variable) can be an object of any of the types that can be returned by expressions 168493: XML and Web Services (II/2546)

  40. The <xsl:param> Element • Both <xsl:variable> and <xsl:param> are used to bind variables • But the value specified on the <xsl:param> variable is only a default value for the binding • The value specified on the <xsl:param> can be changed later 168493: XML and Web Services (II/2546)

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