XSLT, 2nd Edition

Using the format-date() Function

Our last enhancement is to use the new format-date() function to format the date of the purchase order. This is an addition to the function of our XSLT 1.0 stylesheet; everything else we’ve done here has duplicated XSLT 1.0 function in a much simpler way. The date of each purchase order is stored as three attributes named year, month, and day. We’ll use the values of those three attributes to create a new xs:date value, then we’ll use format-date() to format the value.

To create a new xs:date value, we need a string in the format yyyy-mm-dd. xs:date('2006-10-10') is a valid call to the xs:date constructor. To complicate things, the month and day values must have two digits. In other words, xs:date('2006-9-8') raises an error. Our purchase orders don’t necessarily have two-digit month and day values, so we’ll have to write code to add a leading zero if either value is less than 10. Here’s how we do this:

<xsl:variable name="monthValue" as="xs:string"
  select="if (date/@month &lt; 10)
          then concat('0', date/@month)
          else date/@month"/>
<xsl:variable name="dayValue" as="xs:string"
  select="if (date/@day &lt; 10)
          then concat('0', date/@day)
          else date/@day"/>

We compare the value of the attributes to 10; if they’re smaller, we add the string '0' to the value. (Notice that the two variables we’re creating here are of datatype xs:string.) In this code, we have to use the < operator because we’re comparing a node to a number. If we want to use the lt operator, ...