XSL can also add completely new elements into the output file, or remove elements. It can re-order and sort the elements, test and make decisions about which elements to display, and a lot more.]]>
<?xml-stylesheet type="text/xsl" href="filename.xsl" ?> |
The attributes for this processing instruction are as follows:
| Attribute | Description |
| href | Location of the style sheet. The value is a URI, and most of the time will be a URL. |
| type | The Style Sheet Language, expressed as a MIME type. For example, the XSL language MIME type is type/xsl |
But wait, where are we going to place the code in XML document!!! Well, take a look at the example (cd_catalog1.xml) below:
| <?xml
version="1.0" ?> <?xml:stylesheet type="text/xsl" href="cd_catalog.xsl"?> <catalog> | |||
| <cd> | |||
| <title>Painted
Deserted Serenade</title> <artist>Joshue Kadison</artist> <country>USA</country> <company>Capitol Records</company> <price>29.99</price> <year>1993</year> | |||
| </cd> <cd> | |||
| <title>The
Big Picture</title> <artist>Elton John</artist> <country>UK</country> <company>Mercury Records</company> <price>29.95</price> <year>1997</year> | |||
| </cd> <cd> | |||
|
<title>One night only</title> <artist>Bee Gees</artist> <country>UK</country> <company>Polydor</company> <price>29.99</price> <year>1999</year> | |||
| </cd> <cd> | |||
| <title>Classic
Hits</title> <artist>John Paul Young</artist> <country>AUST</country> <company>Albert Productions</company> <price>29.99</price> <year>1988</year> | |||
| </cd> <cd> | |||
| <title>Unchain
My Heart</title> <artist>Joe Crocker</artist> <country>USA</country> <company>EMI</company> <price>14.99</price> <year>1987</year> | |||
| </cd> | |||
| </catalog> | |||
Yep, simply put the stylesheet declaration after the version declaration and just before the document's root element.
From now on, we will use cd_catalog.xml as a foundation for us to build our XSL style sheets. So, remember to include <?xsl-stylesheet type="text/xsl" href="cd_catalog.xsl"?> into cd_catalog.xml document!
]]>1. <?xml version='1.0'?> |
Open cd_catalog.xsl in IE5 or Click here to see output
The
line number above is for ease of tracking only, please do not include
them in the xsl codes.
Explanation:
Line 1. Since an XSL style sheet is an XML file itself, so XSL is case sensitive and the file is therefore must begin with an xml declaration
Line 2. The xsl:stylesheet element indicates that this document is a style sheet. If you add a reference to the above stylesheet to your original XML document, your browser will nicely transform your XML document into HTML.
Line 3. The template has also been wrapped with xsl:template match="/" to indicate that this is a template that corresponds to the root (/) of the XML source document.
xsl:for-each element locates elements in the XML document and repeats a template for each one. The select attribute describes the element in the source document. The syntax for this attribute is called an XSL Pattern, and works like navigating a file system A forward slash (/) selects subdirectories. The xsl:value-of element selects a child in the hierarchy and inserts the content of that child into the template.
The rest of the codes you should be able to recognise 'em right!
]]><xsl:for-each select="catalog/cd" order-by="+ artist">
The order-by attributes takes a plus (+) or minus (-) sign, to define an ascending or descending sort order respectively, and an element name to define the sort element.
Now take a look at your slightly adjusted XSL stylesheet.
| <?xml
version='1.0'?> <xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl"> <xsl:template match="/"> <html> <body> <table border="2" bgcolor="black"> <tr> <th>Title</th> <th>Artist</th> </tr> <xsl:for-each select="catalog/cd" order-by="+ artist"> <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> |
Open it with IE 5 or Click here to see output
As you can see, the Artist column has been sorted alphabetically.
]]><xsl:for-each select="catalog/cd[artist='John Paul Young']"> |
Now take a look at your slightly adjusted XSL stylesheet.
|
<?xml version='1.0'?> |
Open it with IE5 or Click here to see output
In this case, only Artist "John Paul Young" has been selectedLike any other programming language, XSL has four legal filter operators, those are:
| Operator | Meaning |
| = | Equal |
| != | Not equal |
| < | Less than |
| > | Greater than |
| <xsl:if match=".[artist='John
Paul Young']"> ... some output ... </xsl:if> |
Now take a look at your slightly adjusted XSL stylesheet.
|
<?xml version='1.0'?> |
To insert an conditional choose test against the content of the file, simply add the xsl:choose, xsl:when and xsl:otherwise elements to your XSL document like this:
| <xsl:choose> <xsl:when match=".[artist='John Paul Young']"> ... some code ... </xsl:when> <xsl:otherwise> ... some code .... </xsl:otherwise> </xsl:choose> |
Now take a look at your slightly adjusted XSL stylesheet.
|
<?xml version='1.0'?> |
Open it with IE5 or Click here to see output
By using the conditional choose, we can select a specific artist and display it in red color
]]>