Support of RDF-star quoted triples in query results

[Daniel Hernandez]

Hi everyone,

I loaded the following data in Fuseki 4.6.1:

@prefix : <http://example.org/> .
<< :Bob :hasFriend :Alice >> :accordingTo :Alice .

Then, the following query returns :Bob and :Alice, as expected.

PREFIX : <http://example.org/>
SELECT ?s ?o
WHERE {
  << ?s ?p ?o >> ?q ?v. 
}

However, the following query returns an error "e[t].value.replace is not
a function" in the Fuseki UI when selecting the output type as JSON:

PREFIX : <http://example.org/>
SELECT ?t
WHERE {
  ?t ?q ?v .
}

And the following query returns :Alice (without error):

PREFIX : <http://example.org/>
SELECT ?v
WHERE {
  ?t ?q ?v .
}

However, the problematic query works without the Fuseki UI.

curl -G http://localhost:3030/ds/sparql --data-urlencode \
     query='SELECT ?t WHERE { ?t ?q ?v }'
{ "head": {
    "vars": [ "t" ]
  } ,
  "results": {
    "bindings": [
      { 
        "t": {
          "type": "triple" , 
          "value": {
            "subject":  { "type": "uri" , "value": "http://example.org/Bob"; } ,
            "predicate": { "type": "uri" , "value": 
"http://example.org/hasFriend"; } ,
            "object":   { "type": "uri" , "value": "http://example.org/Alice"; }
          }
        }
      }
    ]
  }
}

It seems that this issue only affects the Fuseki UI.

Daniel