Using PHP 5s XSL Extension to Perform XSL Transformations
By Tony Marston2005-04-19
XSL File Contents
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As you can see the XSL file contains a mixture of standard HTML tags and a series of other tags which have the <xsl: prefix. This is similar to a PHP script which can contain a mixture of HTML tags and PHP instructions. Anything which is within an XSL tag will be processed by the XSLT engine in some way, while everything else will be output 'as is'.
Note that this example has its CSS definitions defined internally. In a proper production environment I would expect these to be held in an external file.
Here is an explanation of the various XSL tags:
| <xsl:stylesheet> | Everything within this tag is a stylesheet. Note that the first stylesheet declaration identifies the official W3C XSL recommendation namespace and the version number. |
| <xsl:output /> | This controls the format of the stylesheet output. The default is 'html' with other options being 'xml' and 'text'. Note that the Sablotron extension allows a method of 'xhtml' which ensures that the output conforms to the XHTML rather than the HTML standard. |
| <xsl:param> | This identifies a parameter that can be referenced from anywhere within the stylesheet by its name (but with a '$' prefix). A default value may be declared within the stylesheet, although a different value may be supplied during the transformation process. |
| <xsl:include /> | This is similar to PHP's include function. It allows common stylesheets to be defined once then included as and when necessary. Note that you will need to use the xsl_set_base() command within your PHP script in order to define the base directory which contains the include files. |
| <![CDATA[......]]> | Identifies a piece of text to be ignored by the XML parser. Without this the '<' and '>' would cause errors as the parser would treat them as if they were part of start or end tags. |
| <xsl:template match="/"> | This defines the start of a template. The match="/" attribute associates (matches) the template to the root (/) of the XML source document. |
| <xsl:apply-templates> />; | This defines a set of nodes to be processed. The select="//person" attribute identifies those nodes with the name 'person'. The '//' is used to signify 'child of the root node'. This will look for a template which matches that rule, in this case <xsl:template match="person" > . |
| <xsl:call-template /> | This is used to invoke a named template, as identified by the name attribute. This is analogous to calling a function within PHP. This will look for a template which matches that rule, in this case <xsl:template name="..." > |
| <xsl:value-of /> | This outputs the string value of the expression. The expression can be one of the following:•If it has a '$' prefix then it identifies the <xsl:param> with that name. •Without this prefix it identifies a node within the current path of the XML document. Note that in some cases this tag can be shortened to an expression within curly braces, as in {$script} . This is similar to the use of curly braces within PHP. |
| position() | This equates to the position of the node being tested among its siblings of the same name (i.e. its row number). Note that this number starts from 1, not 0 as in PHP. |
| mod | This produces the modulus of the specified expression. For example, position()mod 2 tells us whether the row number of the current node is odd or even so that we can set the class attribute accordingly. |
| <xsl:attribute> | Inserts an attribute into the current HTML tag. |
| <xsl:choose > <xsl:when >
<xsl:otherwise > | This is equivalent to IF .... ELSEIF .... ELSE |
Tutorial Pages:
» Intended Audience
» Prerequisites
» A Sample XML File
» XML File Contents
» A Sample XSL File
» XSL File Contents
» XSL Include Files
» Performing the XSL Transformation
» Sample Output
» References
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