Using XPath if-then-else

• If your condition is very simple, and the processing you want to do as a result of it does not involve creating elements or attributes, then you can just use an if-then-else structure in XPath:

• xsl:value-of select=count($docAuthors/author) gt 1'Authors: ''Author: ']]>

As we saw in the slide explaining how to use <xsl:if>, this slide shows a simple example of using the XPath if-then-else structure to pluralize author is there is more than one <author> element within <docAuthor>.

• In this case the <xsl:value-of> element has a @select attribute that contains an XPath if-then-else construct
• The first condition, if, contains the XPath expression: count( $docAuthors/author ) gt 1.
• This XPath expression starts by calling the function count(), which counts the number of items in its argument sequence. In this case, the argument to count() is the sequence of child <author> elements found in the variable $docAuthors (presumably the list of authors of the current document :-)
• The XPath expression then asks the question is this (the value of the count() function) greater than one?. That’s what the gt means: greater than.
• The answer to that question (is this (the value of the count() function) greater than one?) is either true() or false().
• If the XPath expression after if is true, then the content following then is returned. Otherwise, the content following else is returned. In this example, if there is more than one <author>, then the condition will return the text: Authors: ; if not, then it will return the text: Author:

XPath if-then-else is useful for when your condition is very simple, and the processing you want to do as a result of it does not involve creating XML constructs like elements and attributes. Also, unlike <xsl:if>, XPath if-then-else allows you to process conditions for both the true() or false() evaluation of an XPath expression.