RE: Using xsl:if to determine if a node is empty.

[Roger Flory <rflory@xxxxxxxxxxxx>]

	[Roger Flory]  Thanks Jeni.  You have been very helpful.  Can you
suggest any classes or seminars where I can learn more about XSL & XPATH?

> Roger,
> 
> You're trying to test here whether the VENDOR_ITEM_NUM element is an empty
> element or not - in other words does it have any child nodes.
> 
> You can form a node set that holds the child nodes of the current node
> (the
> VENDOR_ITEM_NUM element using the XPath:
> 
>   child::node()
> 
> Note however, that this will get *any* node in the content of the element:
> elements, text, processing instructions and even comments.  Probably you
> want to limit this to only elements and text nodes that consist of more
> than just whitespace:
> 
>   child::text()[normalize-space(.)] | child::*
> 
> or, shorter:
> 
>   text()[normalize-space(.)] | *
> 
> These XPaths actually tell you whether the element has any content.  In
> fact, VENDOR_ITEM_NUM probably only takes text children anyway, and it's
> only their value that you care about.  If you are interested in whether
> the
> VENDOR_ITEM_NUM element has some textual content that isn't just
> whitespace
> you can get the nodes that make up that text using just:
> 
>   text()[normalize-space(.)]
> 
> If you just run a test on that node set, then you will get 'true' if there
> are any nodes in the node set, and 'false' if there aren't.  But in a test
> like this, then you can alternatively test whether the current node has a
> 'string value' (which is formed by concatenating together the string
> values
> of all the text and element child nodes), so you can use:
> 
>   normalize-space(.)
> 
> So try:
> 
> <xsl:template match="VENDOR_ITEM_NUM">	
>   <tr>
>     <td></td>
>     <td>
>       <font size="2">
>         <xsl:if test="normalize-space(.)">
>           <xsl:value-of select="concat('Vendor Item number: ',.)"/>
>         </xsl:if>
>       </font>
>     </td>
>   </tr>
> </xsl:template>
> 
> If you want to use a variable to hold an empty string to test against, you
> should probably define it as:
> 
>   <xsl:variable name="empty_string" select="''" />
> 
> as this creates an empty *string* rather than an empty 'result tree
> fragment'.
> 
> You should then be able to test with it as in:
> 
> <xsl:template match="VENDOR_ITEM_NUM">	
>   <tr>
>     <td></td>
>     <td>
>       <font size="2">
>         <xsl:if test="normalize-space(.) != $empty_string">
>           <xsl:value-of select="concat('Vendor Item number: ',.)"/>
>         </xsl:if>
>       </font>
>     </td>
>   </tr>
> </xsl:template>
> 
> but don't forget to normalize-space() the content of the element, just to
> get rid of any whitespace that might be lurking around.
> 
> I hope that this helps,
> 
> Jeni
> 
> Jeni Tennison
> http://www.jenitennison.com/


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