Handling Nil values in XSLT / XQuery

Today I had to generate another batch of DITA files but I discovered that some failed. So the problem was that some dates were nillable and I was formatting the dates so I ran into an exception. So you can in fact pretty easily check if that element has a nil value.

<xsl:variable name="now" select="current-date()"/>
<xsl:variable name="date-format" select="'[Y0001]-[M01]-[D01]T00:00:00'"/>  

<created date="{if (not($productInfo/InitialWebPublicationDate/@xsi:nil='true')) then format-date($productInfo/InitialWebPublicationDate, $date-format) else (format-date($now, $date-format))}"/>

As Ryan Dew commented there is a shorter way like below:

<created date="{if (not(nilled($productInfo/InitialWebPublicationDate))) then format-date($productInfo/InitialWebPublicationDate, $date-format) else (format-date($now, $date-format))}"/>