MarkLogic 12 Product Documentationxdmp:unpath
xdmp:unpath( $expr as xs:string, [$map as map:map?], [$context as node()?], [$options as (element()|map:map)?] ) as item()*
Summary
Evaluate a string as an XPath and return the corresponding node(s).
Any value that is the result of xdmp:path is a
valid input to xdmp:unpath. Any invalid inputs
throw an XDMP-UNPATH exception. To evaluate non-XPath
expressions, use xdmp:value.
| Parameters | |
|---|---|
| expr |
The XPath expression string to evaluate. The XPath expression must be
of the form returned by xdmp:path.
|
| map | A map of namespace bindings. The keys should be namespace prefixes and the values should be namespace URIs. These namespace bindings will be added to the in-scope namespace bindings in the evaluation of the path. |
| context | Bind the context node to this value during evaluation of the expression. |
| options |
Options with which to customize this operation.
You can specify options as either an options XML element
in the namespace "xdmp:eval", or as a map:map. The
option names below are XML localnames. When using a map, replace any
hyphens in an option name with camel casing. For example, "an-option"
becomes "anOption" when used as a map:map entry key.
This function supports the following options:
true, the code is evaluated without using Amps from the caller.
For more details, see
Temporarily Increasing Privileges with Amps.
This option is not usable with dbg:eval.
true, the path runs as if outside of an HTTP App Server:
builtins that read the request (e.g.
xdmp:get-request-header) or write the response (e.g.
xdmp:add-response-header) behave as if called outside of
an HTTP context, typically returning the empty sequence.
Session-related builtins likewise have no session to read or update;
in particular, xdmp:set-session-field returns the set
value instead of creating a new session.
This option is intended as a defense-in-depth control when evaluating
user-supplied paths, and is typically used together with
ignore-amps.
|
Example
xdmp:unpath("/bookstore/book/title")
=> <title>Querying XML</title>
Example
The following example shows how you can use xdmp:unpath and specify namespace bindings that are not in the current query scope.
xquery version "1.0-ml";
let $doc := <html xmlns="http://www.w3.org/1999/xhtml">
<body><p>This is a document</p></body>
</html>
let $namespaces := map:map()
let $_ := map:put($namespaces, "xh", "http://www.w3.org/1999/xhtml")
let $xpath-str := "$doc/xh:body/xh:p"
return xdmp:unpath($xpath-str, $namespaces)
=> <p xmlns="http://www.w3.org/1999/xhtml">This is a document</p>
Example
The following example shows how to use the context node.
xquery version "1.0-ml";
let $doc := <html xmlns="http://www.w3.org/1999/xhtml">
<body><p>This is a document</p></body>
</html>
let $namespaces := map:map()
let $_ := map:put($namespaces, "xh", "http://www.w3.org/1999/xhtml")
let $xpath-str := "/xh:body/xh:p"
return xdmp:unpath($xpath-str, $namespaces, $doc)
=> <p xmlns="http://www.w3.org/1999/xhtml">This is a document</p>
Example
The following example shows that xdmp:unpath
will throw an error if the specified XPath expression
would never be returned by xdmp:path.
xdmp:unpath("/bookstore/book/title[@name eq 'Querying XML']")
=> throws the XDMP-UNPATH exception, because the specified
path expression would never be the output of xdmp:path.