Tim,
I'm pleased that you didn't simply drop the 'as node()' typing - many
people do, but I think it's better to use strong typing wherever
possible. Anyway, I think you want 'as node()?' instead of 'as node()',
and you might consider 'as element(value)?' to use even stronger typing.
http://www.w3.org/TR/xquery/#FunctionDeclns
http://www.w3.org/TR/xquery/#prod-xquery-OccurrenceIndicator
-- Mike
On 2009-06-01 10:26, Tim Meagher wrote:
Hi folks,
This may be a simple xquery syntax issue, but I’ve cut my teeth with xquery in
MarkLogic and thought I’d ask the question here.
There are times that I need to build a node in a function using conditional
logic. For example, given the following function:
declare function aas:build-value-element($qname as xs:string,
$value as xs:string) as node()
{
if ($value ne "") then element value { attribute name {$qname}, $value}
else ()
};
then if a blank value is passed in, e.g.
aas:build-value-element("surname ", "")
then an error is returned:
[1.0-ml] XDMP-AS: (err:XPTY0004) aas:build-value-element("author-surname",
"") -- Invalid coercion: () as node()
So the question is, what is the best way to return an empty node? What I have
been doing to get around this is to return a blank text node, e.g.:
declare function aas:build-value-element($qname as xs:string,
$value as xs:string) as node()
{
if ($value ne "") then element value { attribute name {$qname}, $value}
else text {“”}
};
but the result is that the return node has the extra node in it, albeit a blank
text node.
Are there any best practices for handling this? Is this really an issue – in
all reality does the blank text node get stripped off when storing the results
in an XML document?
Thanks for the help!
Tim Meagher – AAOM Consulting
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