Jason and Evan,
You were both right about the namespace issue, but it wasn't from the document.
It was the context of my xquery - building part of an options node for Search
API, and I didn't realize the namespace would still be implicit when querying
with doc().
E.g.:
declare function local:get-options(){
<options xmlns="http://marklogic.com/appservices/search";>
...
<additional-query>{
...
let $config-info := doc("/config/config-file.xml")//some-element
...
}</additional-query>
...
</options>
So I assume the problem is that the xpath evaluates to //search:some-element --
Is there a way to query the null namespace without doing //*:some-element
(since, as Jason mentioned, that does not use indexes)? Would Evan's xpath be
indexed?: //*[node-name(.) eq fn:QName("","some-element")]
The only thing I can think of is to go out of the scope of the namespace by
calling an outside function, like:
let $config-info := local:get-config-info()
Thanks for your help, guys,
Will
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Evan Lenz
Sent: Wednesday, May 11, 2011 12:35 AM
To: General MarkLogic Developer Discussion
Subject: Re: [MarkLogic Dev General] Node selector xpath not working
Actually, they're not the same thing. The name() function returns the
lexical QName of the element as it appears in the source document (which
might not include a prefix, even if the element is namespace-qualified).
It's better to use the node-name() function, which returns an actual
xs:QName value encapsulating the element's namespace URI and local name.
If [name() eq "some-element"] returns true, all that tells you is that the
element in the source document doesn't use a prefix; it doesn't say one
way or the other whether it uses a namespace, or what the namespace is if
it does. It's generally a bad idea to use the name() function for this,
because adding or changing a prefix in the source document would suddenly
break your code, and prefixes are supposed to be considered insignificant.
In general, you should avoid using the name() function and use node-name()
instead (or a combination of local-name() and namespace-uri()).
(Incidentally, //node()[name() eq "some-element"] will also select
<?some-element?> PIs, but now I'm getting academic...)
Try this instead. In the same query context, the following expression
should always return the same results as //some-element (if more slowly):
//*[node-name(.) eq xs:QName("some-element")]
My guess is that your source document has declared a default namespace,
which means you'll need to declare the same namespace in your XQuery. Look
in the source document to see what the namespace is (xmlns declaration,
typically at the top but could be on any ancestor or the element itself).
And then declare the same namespace in your XQuery (using any prefix):
declare namespace x="http://yournamespace.com";;
//x:some-element
I'm not sure why you're getting different results in the two contexts
(default namespace in effect in one of the two query contexts?), but maybe
this distinction will help you track down the issue.
By the way, behind-the-scenes indexing magic can affect how fast one XPath
expression is versus another, but it should never affect the actual
results you get. This looks like a typical namespace gotcha, but I eagerly
await what you find out. :-)
Evan Lenz
Software Developer, Community
MarkLogic Corporation
On 5/10/11 4:15 PM, "Will Thompson" <[email protected]> wrote:
>Damon,
>
>There is no default namespace in this module - I double-checked using the
>commands you suggested, and the database name is the same as the one
>selected in CQ, and it logs "NS=" for the element I'm trying to select.
>
>Since these two xpaths should evaluate to exactly the same thing:
>
>//some-element
>//node()[name(.)="some-element"]
>
>I'm very surprised that one works and the other doesn't. I know there is
>some behind the scenes ML index magic that I don't understand, but if
>that were the issue, wouldn't it also break in CQ?
>
>Best,
>
>Will
>
>
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Damon
>Feldman
>Sent: Tuesday, May 10, 2011 5:50 PM
>To: General MarkLogic Developer Discussion
>Subject: Re: [MarkLogic Dev General] Node selector xpath not working
>
>Will,
>
>Is there a default namespace at play? You can check by adding:
>
>xdmp:log(text{"NS=", namespace-uri(<cts:elem/>)})
>
>to your module. Similarly, you can check the database by logging
>
>xdmp:database-name(xdmp:database())
>
>to ensure the app server is looking at the data you think it is.
>
>Yours,
>Damon
>
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Will
>Thompson
>Sent: Tuesday, May 10, 2011 3:05 PM
>To: General MarkLogic Developer Discussion
>Subject: [MarkLogic Dev General] Node selector xpath not working
>
>doc("/config/config-file.xml")//some-element
>
>CQ returns the expected elements, but the same query executed through the
>app server returns empty. Same content source. This is how I had to
>work around it in my app:
>
>doc("/config/config-file.xml")//node()[name(.)="some-element"]
>
>I don't see why one would work and not the other. It's not a show
>stopper, but it's definitely bizarre. Any ideas about what could be
>going on?
>
>Thanks,
>
>Will
>_______________________________________________
>General mailing list
>[email protected]
>http://developer.marklogic.com/mailman/listinfo/general
>_______________________________________________
>General mailing list
>[email protected]
>http://developer.marklogic.com/mailman/listinfo/general
>_______________________________________________
>General mailing list
>[email protected]
>http://developer.marklogic.com/mailman/listinfo/general
_______________________________________________
General mailing list
[email protected]
http://developer.marklogic.com/mailman/listinfo/general
_______________________________________________
General mailing list
[email protected]
http://developer.marklogic.com/mailman/listinfo/general
