Can one give me the example for "mode" of template in xsl?

Question

In

<xsl:template name="temp_name" mode="mode">

What is the meaning of mode? I searched many many resource, but i couldn't find example for that. So can anybody explain with an example?

Answer 1

It isn't too meaningful to give a template both a name and a mode.

The name attribute fully identifies a template and there cannot be two templates with the same name and different modes.

The mode attribute allows the same nodes to be processed more than once, using different modes.

Here is a short example:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:template match="num[position() mod 3 = 1]">
  <tr>
    <xsl:apply-templates mode="copy" select=
     ". | following-sibling::*[not(position() >2)]"/>
  </tr>
 </xsl:template>

 <xsl:template match="*" mode="copy">
  <td><xsl:value-of select="."/></td>
 </xsl:template>

 <xsl:template match="num"/>
</xsl:stylesheet>

When this transformation is applied on the following XML document:

<nums>
  <num>01</num>
  <num>02</num>
  <num>03</num>
  <num>04</num>
  <num>05</num>
  <num>06</num>
  <num>07</num>
  <num>08</num>
  <num>09</num>
  <num>10</num>
</nums>

The result is that the numbers are displayed in three tr (rows), each containing three columns (with the possible exception of the last row):

<tr>
   <td>01</td>
   <td>02</td>
   <td>03</td>
</tr>
<tr>
   <td>04</td>
   <td>05</td>
   <td>06</td>
</tr>
<tr>
   <td>07</td>
   <td>08</td>
   <td>09</td>
</tr>
<tr>
   <td>10</td>
</tr>

In this transformation, any num element with position that cannot be represented in the form 3*k +1 (where k is an integer), is matched by a template with empty body and thus isn't processed.

However, we want to process all num elements that should form the cells of a row. For this purpuse, we are processing them using the xslt instruction:

<xsl:apply-templates mode="copy" select=
 ". | following-sibling::*[not(position() >2)]"/>

which means: "Do not apply to the selected nodes templates that would normally be applied (in no mode), but apply templates that are in copy mode"

Thus, we do not ignore the selected num elements, but are processing them in copy mode and are creating the td s of a row.

The template rule:

<xsl:template match="num"/>

is necessary to override the xslt builtin templates (default processing) that would otherwise cause the string values of the num nodes whose position cannot be represented as 3*k +1, to be output.

So, these nodes are processed by both templates:

<xsl:template match="num"/>

and

<xsl:apply-templates mode="copy" select=
 ". | following-sibling::*[not(position() >2)]"/>

and thus we get the wanted result.

It would be instructive to step through with a good XSLT debugger in order to see how these templates are applied.