Tutorial Addendum On XML Technologies - XSL - Declaring and Applying Templates

The apply-templates Element

    

apply-templates: An XSL aspect confined as an activity statement. It requests

    

the XSL processor to administer transformation templates to assertive elements in the

    

source XML file.

    

    
<xsl:apply-templates select="pattern"/>

    
<xsl:apply-templates/>

    

where "pattern" is a arrangement acclimated to bout aspect names in the antecedent XML file.

    

An "apply-templates" account is alone acclimated central a "template" statement,

    

and the "pattern" analogous action is done in advertence to the accepted aspect on which

    

the "template" account has been applied. For example, if "pattern" is an element

    

name, it will be akin alone adjoin adolescent elements of the accepted element.

    

The achievement of the requested transformation on the akin elements will be allotment of

    

the backup agreeable of the accepted element.

    

If "pattern" matches no element, annihilation will happen.

    

If "pattern" matches assorted elements, all of the akin elements will be transformed.

    

If aspect "select" is not specified, all adolescent elements will be transformed.

    

Example:

    

 

    
 <xsl:template match="p">

    
  Argument allotment 1.

    
  <xsl:apply-templates select="q"/>

    
  Argument allotment 2.

    
 </xsl:template>

    

The achievement of the transformation on aspect "q" will be amid amid argument allotment 1

    

and 2, if this arrangement is acclimated to transform aspect "p". Bold aspect "q" is

    

a adolescent aspect of aspect "p".

    

How XSL Transformation Gets Started?

    

With "template" and "apply-templates" elements, we can now attending at how the XSL

    

transformation gets started, and in which adjustment the elements in the antecedent XML

    

file get processed.

    

First, let s analysis the hello_xsl.xml:

    

 

    
<?xml version="1.0"?>

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

    
<p>Hello world!</p>

    

the hello.xsl:

    

 

    
<?xml version="1.0"?>

    
<xsl:stylesheet version="1.0"

    
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    
 <xsl:template match="p">Hello world.! - From hello.xsl.</xsl:template>

    
</xsl:stylesheet>

    

and the achievement from Internet Explorer by openning hello_xsl.xml:

    

 

    
Hello world! - From hello.xsl.

    

Question: Area is the "apply-templates" account for aspect "p"? Who requested

    

to administer transformation arrangement on aspect "p"? My assumption is that the XSL processor

    

automatically starts the transformation on the basis element, which is "p" in our example.

    

Rule: XSL processors automatically alpha to administer transformation on the basis element.

    

The afterward XSL statements is not needed, aswell not accustomed anon beneath "stylesheet":

    

 

    
<xsl:apply-templates select="root_element_name"/>

    

Default Transformation Template

    

Question: How an aspect will be adapted if there is no arrangement authentic

    

for that element?

    

So let s adapt hello.xsl to:

    

 

    
<?xml version="1.0"?>

    
<xsl:stylesheet version="1.0"

    
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    
</xsl:stylesheet>

    

and appearance hello_xsl.xml in IE, you will get:

    

 

    
Hello world!

    

It seemed to me that the IE supplied a absence transformation template.

    

Rule: XSL processors use a absence transformation arrangement for elements for which

    

there is no arrangement authentic in the appearance sheet. The behavior of the absence arrangement

    

is to archetype alone argument allotment of the aspect s agreeable to the output.