[xquery-talk] How to handle empty sequence?
tenacious61 at sbcglobal.net
Thu Jan 20 00:27:17 PST 2005
Thank you. It took me a while to realize the last "for" loop I had,
could be completely replaced by your suggestion, pulling the first
element of the sequence directly. It works perfectly.
From: talk-bounces at xquery.com [mailto:talk-bounces at xquery.com]On Behalf
Of Michael Kay
Sent: Tuesday, January 18, 2005 1:32 AM
To: 'Ed O'Neill'; talk at xquery.com
Subject: RE: [xquery-talk] How to handle empty sequence?
> let $version := ($release3/version)
> if (string-length(string($version/node())) =
> 0) then "NA"
> else $version/node()
> This query works fine if all applications have a version in each
> environment. The problem is when I have an application that
> does not have
> any versions released to a particular env. .When this occurs, the
> $sorted_releases sequence will be empty, so I never get to
> "for $release3"
> return to generate the necessary table element (which would be blank).
Yes, you can't do $version/node() if $version is a string. But why are you
doing $version/node() anyway? If the input is <version>13<!--I
think--></version>, this will fail because the version element has two child
nodes, and string() must take a singleton as its argument. Better to take
the string value of the element node itself.
I would do
let $version = string(($release3/version, "NA"))
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