Make a UNION return a single result in SPARQL - sparql

Question

I am trying to query for the sh:description of a property shape, and if there is none, I want to follow the path to a property and get the rdfs:comment (Also for sh:name and rdfs:label). My data looks like the following:
ex:File
a owl:Class ;
a sh:NodeShape ;
sh:property ex:File-name ;
ex:File-name
a sh:PropertyShape ;
sh:path ex:filename ;
sh:datatype xsd:string ;
sh:description "The name of the file" ;
sh:maxCount 1 ;
ex:filename
a rdf:Property ;
rdfs:label "Filename" ;
rdfs:comment "The file name" ;
.
I have the query below, but it returns two results. How can I modify it to only return a single result (preferring sh:description over rdfs:comment)?
PREFIX : <http://www.example.org/#>
PREFIX sh: <http://www.w3.org/ns/shacl#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
select ?propertyShape ?property ?name ?description where {
:File sh:property ?propertyShape .
?propertyShape sh:path ?property .
{ ?propertyShape sh:name ?name } UNION { ?property rdfs:label ?name } .
{ ?propertyShape sh:description ?description } UNION { ?property rdfs:comment ?description } .
The above returns something like this:
propertyShape
property
name
description
:File-name
ex:filename
"Filename"
"The name of the file"
:File-name
ex:filename
"Filename"
"The file name"
I would like for it to return something like:
propertyShape
property
name
description
:File-name
ex:filename
"Filename"
"The name of the file"

Answer 1

You should be able to use a sequence of OPTIONAL blocks to do this:
SELECT ?propertyShape ?property ?name ?description WHERE {
:File sh:property ?propertyShape .
?propertyShape sh:path ?property .
OPTIONAL { ?propertyShape sh:name ?name }
OPTIONAL { ?property rdfs:label ?name }
OPTIONAL { ?propertyShape sh:description ?description }
OPTIONAL { ?property rdfs:comment ?description }
}
You'll still have to think about cases where there are multiple names/descriptions per property (this isn't guaranteed to return just a single result), but it should give you the "preferring sh:description over rdfs:comment" behavior.

Answer 2

Can't you just use path expressions such as
...
?propertyShape sh:name|(sh:path/rdfs:label) ?name .
?propertyShape sh:description|(sh:path/rdfs:comment) ?description .