xsl:copy

Nikolai Grigoriev

Suppose I have the following XML:

<employee FullSecurity="0">
  <name>John Doe</name>
  <department>Widget Sales</department>
  <phone>(555)555-5555<
extension>2974</extension></phone>
  <salary>62,000</salary>
  <area>3</area>
</employee>

I want to create a very simple XSL stylesheet which does the
following: If the FullSecurity attribute evaluates to
"true", then copy all of the source tree to the
result tree.  If the FullSecurity attribute evaluates to
"false", copy all of the source tree *except for the
<salary> element* to the result tree.


My solution is 4 lines in 2 templates (not counting the comments):

<!-- By default, copy a node with all the 
        children through. -->
<!-- Attributes are dropped; to include them, 
        use match="*|@*" -->

<xsl:template match="*">
  <xsl:copy> <xsl:apply-templates/> </xsl:copy>
</xsl:template>

<!-- Processing of salary nodes is disabled for 
   FullSecurity="0" -->
<xsl:template match="salary[/employee/@FullSecurity=0]"/>

            

Mike Kay +

general principle: xsl:copy-of for a deep copy, xsl:copy for a shallow copy, xsl:apply-templates for a transformation.

I.e. xsl:copy copies the current node, sub-elements are not copied xsl:copy-of copies nodes and all their descendants.

Oliver Becker

> I want to write an xsl that will
> basically copy an xml tree, but allow me to chnage the values of certain
> nodes. For example:
> 
> <highlevel>Highest Level
> <innernode>This is an innernode
> <lownode>This is a low-level node</lownode>
> </innernode>
> </highlevel>
> 
> I want to copy this, but change the text of <innernode>, such as 
> 
> <highlevel>Highest Level
> <innernode>I have edited this text
> <lownode>This is a low-level node</lownode>
> </innernode>
> </highlevel>
> 
    

You shouldn't use xsl:copy-of. This makes a deep copy without processing the inner elements. Use xsl:copy and xsl:apply-templates - see the identity transformation in the XSLT spec http://www.w3.org/TR/xslt#copying

<xsl:template match="@*|node()">
   <xsl:copy>
      <xsl:apply-templates select="@*|node()"/>
   </xsl:copy>
</xsl:template>

Now you can add special templates for special element nodes, such as innernode. But note: to process lownode you should call xsl:apply-templates as well. So your template becomes

<xsl:template match="innernode">
	<innernode>
	I have edited this node
	<xsl:apply-templates select="*" />  
     <!-- only elements, no text nodes -->
	</innernode>
</xsl:template>

I haven't tested it, but it should work.

David Carlisle

xsl:copy-of select="@*" is the standard way of copying all attributes.

However You can simplify

to either

or

and you can simplify

to

actually if that was exactly what you wanted, you are just copying an entire element, so you could further simplify to

so