XQuery: convert XML to RDF - xquery

Question

I am trying to convert XML to RDF(RDF/XML syntax) using XQuery. I think I encounter something I could not overcome...
test.xqy:
declare namespace rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#";
declare namespace owl="http://www.w3.org/2002/07/owl#";
declare namespace xsd="http://www.w3.org/2001/XMLSchema#";
declare namespace rdfs="http://www.w3.org/2000/01/rdf-schema#";
import module namespace functx="http://www.functx.com";
declare variable $srcDoc:="test.xml";
declare variable $defaultXMLNS:="http://www.test.com#";
declare variable $defaultXMLBase:=$defaultXMLNS;
declare function local:getQName($local as xs:string?)
as xs:QName?
{
QName($defaultXMLNS, $local)
};
declare function local:namedIndividualConstructor($pnode as node()*)
as node()*
{
element owl:NamedIndividual
{
(:to avoid repeated names, unique uuid is generated for each individuals:)
attribute rdf:about {concat("#", random:uuid(), "_", $pnode/name())},
element rdf:type {attribute rdf:resource {concat("#", $pnode/name())}},
for $x in $pnode/*
return element {local:getQName(concat($pnode/name(), "_", $x/name()))}
{
attribute rdf:resource {}
}
}
};
element rdf:RDF
{
namespace {""} {$defaultXMLNS},
attribute xml:base {$defaultXMLBase},
element owl:Ontology
{
attribute rdf:about {$defaultXMLNS}
},
for $x in doc($srcDoc)//*
return if($x[not(child::*)])
then ()
(:only generate namedIndividual for nodes having leaf nodes:)
else local:namedIndividualConstructor($x)
}
test.xml:
<?xml version="1.0" encoding="UTF-8"?>
<breakfast_menu>
<food>
<name>French Toast aaa</name>
<price>$5.95</price>
<description>Our famous Belgian Waffles with plenty of real maple syrup</description>
<calories>650</calories>
</food>
<food>
<name>French Toast</name>
<price>$4.50</price>
<description>Thick slices made from our homemade sourdough bread</description>
<calories>600</calories>
</food>
<food>
<name>Homestyle Breakfast</name>
<price>$6.95</price>
<description>Two eggs, bacon or sausage, toast, and our ever-popular hash browns</description>
<calories>950</calories>
</food>
</breakfast_menu>
command line:
basex -o testxqyoutput.rdf test.xqy
testxqyoutput.rdf:
<rdf:RDF xmlns="http://www.test.com#" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xml:base="http://www.test.com#">
<owl:Ontology xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="http://www.test.com#"/>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#82ab6f48-2faf-4782-840f-59e6e96403ef_breakfast_menu">
<rdf:type rdf:resource="#breakfast_menu"/>
<breakfast_menu_food rdf:resource=""/>
<breakfast_menu_food rdf:resource=""/>
<breakfast_menu_food rdf:resource=""/>
</owl:NamedIndividual>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#04f02acc-da19-47a7-a69a-98cc958efbbd_food">
<rdf:type rdf:resource="#food"/>
<food_name rdf:resource=""/>
<food_price rdf:resource=""/>
<food_description rdf:resource=""/>
<food_calories rdf:resource=""/>
</owl:NamedIndividual>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#bfec0a13-ac56-4ac8-a9bb-0575b16e601a_food">
<rdf:type rdf:resource="#food"/>
<food_name rdf:resource=""/>
<food_price rdf:resource=""/>
<food_description rdf:resource=""/>
<food_calories rdf:resource=""/>
</owl:NamedIndividual>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#7f6411cb-3619-4b61-8b78-3b1e8ec99898_food">
<rdf:type rdf:resource="#food"/>
<food_name rdf:resource=""/>
<food_price rdf:resource=""/>
<food_description rdf:resource=""/>
<food_calories rdf:resource=""/>
</owl:NamedIndividual>
</rdf:RDF>
I use uuid to avoid duplicate child element, so for different <food>, there is a different name. The output testxqyoutput.rdf may not look like a valid rdf file, I discarded some not related details of the source code.
The real problem is: I don't know how to assign the corresponding name to rdf:resource.
The first generated NamedIndividual should look like this:
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#82ab6f48-2faf-4782-840f-59e6e96403ef_breakfast_menu">
<rdf:type rdf:resource="#breakfast_menu"/>
<breakfast_menu_food rdf:resource="#04f02acc-da19-47a7-a69a-98cc958efbbd_food"/>
<breakfast_menu_food rdf:resource="#bfec0a13-ac56-4ac8-a9bb-0575b16e601a_food"/>
<breakfast_menu_food rdf:resource="#7f6411cb-3619-4b61-8b78-3b1e8ec99898_food"/>
</owl:NamedIndividual>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#04f02acc-da19-47a7-a69a-98cc958efbbd_food">
<rdf:type rdf:resource="#food"/>
<food_name rdf:resource=""/>
<food_price rdf:resource=""/>
<food_description rdf:resource=""/>
<food_calories rdf:resource=""/>
</owl:NamedIndividual>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#bfec0a13-ac56-4ac8-a9bb-0575b16e601a_food">
<rdf:type rdf:resource="#food"/>
<food_name rdf:resource=""/>
<food_price rdf:resource=""/>
<food_description rdf:resource=""/>
<food_calories rdf:resource=""/>
</owl:NamedIndividual>
<owl:NamedIndividual xmlns:owl="http://www.w3.org/2002/07/owl#" rdf:about="#7f6411cb-3619-4b61-8b78-3b1e8ec99898_food">
<rdf:type rdf:resource="#food"/>
<food_name rdf:resource=""/>
<food_price rdf:resource=""/>
<food_description rdf:resource=""/>
<food_calories rdf:resource=""/>
</owl:NamedIndividual>
How do I modify the code to achieve this valid output?
I think the real problem is: XQuery is functional programming language. And all NamedIndividuals are generated by a function. There is no way to share status between functions. And there is no concept global variable in XQuery...

Answer 1

I would expect something like this could work. Besides, am I right the attribute rdf:resource {} in your code does nothing because it is empty?
declare function local:namedIndividualConstructor($pnode as node()*)
as node()*
{
(:to avoid repeated names, unique uuid is generated for each individuals:)
let $id := concat("#", random:uuid(), "_", $pnode/name())
element owl:NamedIndividual
{
attribute rdf:about {$id},
element rdf:type {attribute rdf:resource {concat("#", $pnode/name())}},
for $x in $pnode/*
return element {local:getQName(concat($pnode/name(), "_", $x/name()))}
{
attribute rdf:resource {$id}
}
}
};