fn:resolve-QName

Returns an xs:QName value (that is, an expanded-QName) by taking an xs:string that has the lexical form of an xs:QName (a string in the form "prefix:local-name" or "local-name") and resolving it using the in-scope namespaces for a given element.

Signature

fn:resolve-QName(
    $qname as xs:string?, 
    $element as element()
) as xs:QName?

Properties

This function is deterministic, context-independent, and focus-independent.

Rules

If $qname is the empty sequence, returns the empty sequence.

More specifically, the function searches the namespace bindings of $element for a binding whose name matches the prefix of $qname, or the zero-length string if it has no prefix, and returns an expanded-QName whose local name is taken from the supplied $qname, and whose namespace URI is taken from the string value of the namespace binding.

If the $qname has no prefix, and there is no namespace binding for $element corresponding to the default (unnamed) namespace, then the resulting expanded-QName has no namespace part.

The prefix (or absence of a prefix) in the supplied $qname argument is retained in the returned expanded-QName, as described in Terminology.

Error Conditions

A dynamic error is raised [ERRFOCA0002] if $qname does not have the correct lexical form for an instance of xs:QName.

A dynamic error is raised [ERRFONS0004] if $qname has a prefix and there is no namespace binding for $element that matches this prefix.

Notes

Sometimes the requirement is to construct an xs:QName without using the default namespace. This can be achieved by writing:

if (contains($qname, ":")) then fn:resolve-QName($qname, $element) else
            fn:QName("", $qname)

If the requirement is to construct an xs:QName using the namespaces in the static context, then the xs:QName constructor should be used.

Examples

Assume that the element bound to $element has a single namespace binding bound to the prefix eg.

fn:resolve-QName("hello", $element) returns a QName with local name "hello" that is in no namespace.

fn:resolve-QName("eg:myFunc", $element) returns an xs:QName whose namespace URI is specified by the namespace binding corresponding to the prefix "eg" and whose local name is "myFunc".