xquery exception [XPTY0019] - exception

Question

I am using the following xml file (users_doc.xml)
<users>
<user trusted="false">
<userid>vsony7#vt.edu</userid>
<password>sony</password>
</user>
<user trusted="false">
<userid>shivi</userid>
<password>shivi</password>
</user>
<user trusted="false">
<userid>xyz</userid>
<password>xyz</password>
</user>
</users>
I am running the following xquery: (Here $doc_name=users_doc, $userid=xyz)
declare variable $doc_name as xs:string external;
declare variable $userid as xs:string external;
let $users_doc := doc($doc_name)/users
return delete node $users_doc/user/userid=$userid/..
I am trying to find a given node <userid>xyz</userid> and if the user exists I would like to delete its parent node
<user trusted="false">
<userid>xyz</userid>
<password>xyz</password>
</user>
But, when I run this query I get the following exception:
Exception in thread "main" java.io.IOException: Stopped at line 5, column 51:
[XPTY0019] Context node required for ..; xs:string found.
How do I fix this ?
Thanks,
Sony

Answer 1

From http://www.w3.org/TR/xquery/#ERRXPTY0019
err:XPTY0019
It is a type error if the result of a step (other than
the last step) in a path expression
contains an atomic value.
Let's look at your expression:
$users_doc/user/userid=$userid/..
The left term of the last step is a node set comparison:
$users_doc/user/userid=$userid
So, it will result in true or false boolean value (an atomic value). Of course, you can't select the parent::node() of true or false...
You want this expression:
$users_doc/user[userid=$userid]